redict/tests/unit/wait.tcl

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2024-03-21 09:30:47 -04:00
# SPDX-FileCopyrightText: 2024 Redict Contributors
# SPDX-FileCopyrightText: 2024 Salvatore Sanfilippo <antirez at gmail dot com>
#
# SPDX-License-Identifier: BSD-3-Clause
# SPDX-License-Identifier: LGPL-3.0-only
2024-03-21 09:30:47 -04:00
source tests/support/cli.tcl
Improve test suite to handle external servers better. (#9033) This commit revives the improves the ability to run the test suite against external servers, instead of launching and managing `redis-server` processes as part of the test fixture. This capability existed in the past, using the `--host` and `--port` options. However, it was quite limited and mostly useful when running a specific tests. Attempting to run larger chunks of the test suite experienced many issues: * Many tests depend on being able to start and control `redis-server` themselves, and there's no clear distinction between external server compatible and other tests. * Cluster mode is not supported (resulting with `CROSSSLOT` errors). This PR cleans up many things and makes it possible to run the entire test suite against an external server. It also provides more fine grained controls to handle cases where the external server supports a subset of the Redis commands, limited number of databases, cluster mode, etc. The tests directory now contains a `README.md` file that describes how this works. This commit also includes additional cleanups and fixes: * Tests can now be tagged. * Tag-based selection is now unified across `start_server`, `tags` and `test`. * More information is provided about skipped or ignored tests. * Repeated patterns in tests have been extracted to common procedures, both at a global level and on a per-test file basis. * Cleaned up some cases where test setup was based on a previous test executing (a major anti-pattern that repeats itself in many places). * Cleaned up some cases where test teardown was not part of a test (in the future we should have dedicated teardown code that executes even when tests fail). * Fixed some tests that were flaky running on external servers.
2021-06-09 08:13:24 -04:00
start_server {tags {"wait network external:skip"}} {
start_server {} {
set slave [srv 0 client]
set slave_host [srv 0 host]
set slave_port [srv 0 port]
set slave_pid [srv 0 pid]
set master [srv -1 client]
set master_host [srv -1 host]
set master_port [srv -1 port]
test {Setup slave} {
$slave slaveof $master_host $master_port
wait_for_condition 50 100 {
[s 0 master_link_status] eq {up}
} else {
fail "Replication not started."
}
}
test {WAIT out of range timeout (milliseconds)} {
# Timeout is parsed as milliseconds by getLongLongFromObjectOrReply().
# Verify we get out of range message if value is behind LLONG_MAX
# (decimal value equals to 0x8000000000000000)
assert_error "*or out of range*" {$master wait 2 9223372036854775808}
# expected to fail by later overflow condition after addition
# of mstime(). (decimal value equals to 0x7FFFFFFFFFFFFFFF)
assert_error "*timeout is out of range*" {$master wait 2 9223372036854775807}
assert_error "*timeout is negative*" {$master wait 2 -1}
}
test {WAIT should acknowledge 1 additional copy of the data} {
$master set foo 0
$master incr foo
$master incr foo
$master incr foo
assert {[$master wait 1 5000] == 1}
assert {[$slave get foo] == 3}
}
test {WAIT should not acknowledge 2 additional copies of the data} {
$master incr foo
assert {[$master wait 2 1000] <= 1}
}
test {WAIT should not acknowledge 1 additional copy if slave is blocked} {
pause_process $slave_pid
$master set foo 0
$master incr foo
$master incr foo
$master incr foo
assert {[$master wait 1 1000] == 0}
resume_process $slave_pid
assert {[$master wait 1 1000] == 1}
}
test {WAIT implicitly blocks on client pause since ACKs aren't sent} {
pause_process $slave_pid
$master multi
$master incr foo
$master client pause 10000 write
$master exec
assert {[$master wait 1 1000] == 0}
$master client unpause
resume_process $slave_pid
assert {[$master wait 1 1000] == 1}
}
test {WAIT replica multiple clients unblock - reuse last result} {
set rd [redict_deferring_client -1]
set rd2 [redict_deferring_client -1]
pause_process $slave_pid
$rd incr foo
$rd read
$rd2 incr foo
$rd2 read
$rd wait 1 0
$rd2 wait 1 0
wait_for_blocked_clients_count 2 100 10 -1
resume_process $slave_pid
assert_equal [$rd read] {1}
assert_equal [$rd2 read] {1}
$rd ping
assert_equal [$rd read] {PONG}
$rd2 ping
assert_equal [$rd2 read] {PONG}
$rd close
$rd2 close
}
}}
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
tags {"wait aof network external:skip"} {
start_server {overrides {appendonly {yes} auto-aof-rewrite-percentage {0}}} {
set master [srv 0 client]
test {WAITAOF local copy before fsync} {
r config set appendfsync no
$master incr foo
assert_equal [$master waitaof 1 0 50] {0 0} ;# exits on timeout
r config set appendfsync everysec
}
test {WAITAOF local copy everysec} {
$master incr foo
assert_equal [$master waitaof 1 0 0] {1 0}
}
test {WAITAOF local copy with appendfsync always} {
r config set appendfsync always
$master incr foo
assert_equal [$master waitaof 1 0 0] {1 0}
}
test {WAITAOF local wait and then stop aof} {
r config set appendfsync no
set rd [redict_deferring_client]
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
$rd incr foo
$rd read
$rd waitaof 1 0 0
wait_for_blocked_client
r config set appendonly no ;# this should release the blocked client as an error
assert_error {ERR WAITAOF cannot be used when numlocal is set but appendonly is disabled.} {$rd read}
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
$rd close
}
test {WAITAOF local on server with aof disabled} {
$master incr foo
assert_error {ERR WAITAOF cannot be used when numlocal is set but appendonly is disabled.} {$master waitaof 1 0 0}
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
}
test {WAITAOF local if AOFRW was postponed} {
r config set appendfsync everysec
# turn off AOF
r config set appendonly no
# create an RDB child that takes a lot of time to run
r set x y
r config set rdb-key-save-delay 100000000 ;# 100 seconds
r bgsave
assert_equal [s rdb_bgsave_in_progress] 1
# turn on AOF
r config set appendonly yes
assert_equal [s aof_rewrite_scheduled] 1
# create a write command (to increment master_repl_offset)
r set x y
# reset save_delay and kill RDB child
r config set rdb-key-save-delay 0
catch {exec kill -9 [get_child_pid 0]}
# wait for AOF (will unblock after AOFRW finishes)
assert_equal [r waitaof 1 0 10000] {1 0}
# make sure AOFRW finished
assert_equal [s aof_rewrite_in_progress] 0
assert_equal [s aof_rewrite_scheduled] 0
}
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
$master config set appendonly yes
waitForBgrewriteaof $master
start_server {overrides {appendonly {yes} auto-aof-rewrite-percentage {0}}} {
set master_host [srv -1 host]
set master_port [srv -1 port]
set replica [srv 0 client]
set replica_host [srv 0 host]
set replica_port [srv 0 port]
set replica_pid [srv 0 pid]
# make sure the master always fsyncs first (easier to test)
$master config set appendfsync always
$replica config set appendfsync no
test {WAITAOF on demoted master gets unblocked with an error} {
set rd [redict_deferring_client]
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
$rd incr foo
$rd read
$rd waitaof 0 1 0
wait_for_blocked_client
$replica replicaof $master_host $master_port
assert_error {UNBLOCKED force unblock from blocking operation,*} {$rd read}
$rd close
}
wait_for_ofs_sync $master $replica
test {WAITAOF replica copy before fsync} {
$master incr foo
assert_equal [$master waitaof 0 1 50] {1 0} ;# exits on timeout
}
$replica config set appendfsync everysec
test {WAITAOF replica copy everysec} {
Fix fork done handler wrongly update fsync metrics and enhance AOF_ FSYNC_ALWAYS (#11973) This PR fix several unrelated bugs that were discovered by the same set of tests (WAITAOF tests in #11713), could make the `WAITAOF` test hang. The change in `backgroundRewriteDoneHandler` is about MP-AOF. That leftover / old code assumes that we started a new AOF file just now (when we have a new base into which we're gonna incrementally write), but the fact is that with MP-AOF, the fork done handler doesn't really affect the incremental file being maintained by the parent process, there's no reason to re-issue `SELECT`, and no reason to update any of the fsync variables in that flow. This should have been deleted with MP-AOF (introduced in #9788, 7.0). The damage is that the update to `aof_fsync_offset` will cause us to miss an fsync in `flushAppendOnlyFile`, that happens if we stop write commands in `AOF_FSYNC_EVERYSEC` while an AOFRW is in progress. This caused a new `WAITAOF` test to sometime hang forever. Also because of MP-AOF, we needed to change `aof_fsync_offset` to `aof_last_incr_fsync_offset` and match it to `aof_last_incr_size` in `flushAppendOnlyFile`. This is because in the past we compared `aof_fsync_offset` and `aof_current_size`, but with MP-AOF it could be the total AOF file will be smaller after AOFRW, and the (already existing) incr file still has data that needs to be fsynced. The change in `flushAppendOnlyFile`, about the `AOF_FSYNC_ALWAYS`, it is follow #6053 (the details is in #5985), we also check `AOF_FSYNC_ALWAYS` to handle a case where appendfsync is changed from everysec to always while there is data that's written but not yet fsynced.
2023-03-29 08:17:05 -04:00
$replica config set appendfsync everysec
waitForBgrewriteaof $replica ;# Make sure there is no AOFRW
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
$master incr foo
assert_equal [$master waitaof 0 1 0] {1 1}
}
Fix fork done handler wrongly update fsync metrics and enhance AOF_ FSYNC_ALWAYS (#11973) This PR fix several unrelated bugs that were discovered by the same set of tests (WAITAOF tests in #11713), could make the `WAITAOF` test hang. The change in `backgroundRewriteDoneHandler` is about MP-AOF. That leftover / old code assumes that we started a new AOF file just now (when we have a new base into which we're gonna incrementally write), but the fact is that with MP-AOF, the fork done handler doesn't really affect the incremental file being maintained by the parent process, there's no reason to re-issue `SELECT`, and no reason to update any of the fsync variables in that flow. This should have been deleted with MP-AOF (introduced in #9788, 7.0). The damage is that the update to `aof_fsync_offset` will cause us to miss an fsync in `flushAppendOnlyFile`, that happens if we stop write commands in `AOF_FSYNC_EVERYSEC` while an AOFRW is in progress. This caused a new `WAITAOF` test to sometime hang forever. Also because of MP-AOF, we needed to change `aof_fsync_offset` to `aof_last_incr_fsync_offset` and match it to `aof_last_incr_size` in `flushAppendOnlyFile`. This is because in the past we compared `aof_fsync_offset` and `aof_current_size`, but with MP-AOF it could be the total AOF file will be smaller after AOFRW, and the (already existing) incr file still has data that needs to be fsynced. The change in `flushAppendOnlyFile`, about the `AOF_FSYNC_ALWAYS`, it is follow #6053 (the details is in #5985), we also check `AOF_FSYNC_ALWAYS` to handle a case where appendfsync is changed from everysec to always while there is data that's written but not yet fsynced.
2023-03-29 08:17:05 -04:00
test {WAITAOF replica copy everysec with AOFRW} {
$replica config set appendfsync everysec
# When we trigger an AOFRW, a fsync is triggered when closing the old INCR file,
# so with the everysec, we will skip that second of fsync, and in the next second
# after that, we will eventually do the fsync.
$replica bgrewriteaof
waitForBgrewriteaof $replica
$master incr foo
assert_equal [$master waitaof 0 1 0] {1 1}
}
test {WAITAOF replica copy everysec with slow AOFRW} {
$replica config set appendfsync everysec
$replica config set rdb-key-save-delay 1000000 ;# 1 sec
$replica bgrewriteaof
$master incr foo
assert_equal [$master waitaof 0 1 0] {1 1}
$replica config set rdb-key-save-delay 0
waitForBgrewriteaof $replica
}
test {WAITAOF replica copy everysec->always with AOFRW} {
$replica config set appendfsync everysec
# Try to fit all of them in the same round second, although there's no way to guarantee
# that, it can be done on fast machine. In any case, the test shouldn't fail either.
$replica bgrewriteaof
$master incr foo
waitForBgrewriteaof $replica
$replica config set appendfsync always
assert_equal [$master waitaof 0 1 0] {1 1}
}
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
test {WAITAOF replica copy appendfsync always} {
$replica config set appendfsync always
$master incr foo
assert_equal [$master waitaof 0 1 0] {1 1}
$replica config set appendfsync everysec
}
test {WAITAOF replica copy if replica is blocked} {
pause_process $replica_pid
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
$master incr foo
assert_equal [$master waitaof 0 1 50] {1 0} ;# exits on timeout
resume_process $replica_pid
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
assert_equal [$master waitaof 0 1 0] {1 1}
}
test {WAITAOF replica multiple clients unblock - reuse last result} {
set rd [redict_deferring_client -1]
set rd2 [redict_deferring_client -1]
pause_process $replica_pid
$rd incr foo
$rd read
$rd2 incr foo
$rd2 read
$rd waitaof 0 1 0
$rd2 waitaof 0 1 0
wait_for_blocked_clients_count 2 100 10 -1
resume_process $replica_pid
assert_equal [$rd read] {1 1}
assert_equal [$rd2 read] {1 1}
$rd ping
assert_equal [$rd read] {PONG}
$rd2 ping
assert_equal [$rd2 read] {PONG}
$rd close
$rd2 close
}
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
test {WAITAOF on promoted replica} {
$replica replicaof no one
$replica incr foo
assert_equal [$replica waitaof 1 0 0] {1 0}
}
test {WAITAOF master that loses a replica and backlog is dropped} {
$master config set repl-backlog-ttl 1
after 2000 ;# wait for backlog to expire
$master incr foo
assert_equal [$master waitaof 1 0 0] {1 0}
}
test {WAITAOF master without backlog, wait is released when the replica finishes full-sync} {
set rd [redict_deferring_client -1]
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
$rd incr foo
$rd read
$rd waitaof 0 1 0
wait_for_blocked_client -1
$replica replicaof $master_host $master_port
assert_equal [$rd read] {1 1}
$rd close
}
test {WAITAOF master isn't configured to do AOF} {
$master config set appendonly no
$master incr foo
assert_equal [$master waitaof 0 1 0] {0 1}
}
test {WAITAOF replica isn't configured to do AOF} {
$master config set appendonly yes
waitForBgrewriteaof $master
$replica config set appendonly no
$master incr foo
assert_equal [$master waitaof 1 0 0] {1 0}
}
test {WAITAOF both local and replica got AOF enabled at runtime} {
$replica config set appendonly yes
waitForBgrewriteaof $replica
$master incr foo
assert_equal [$master waitaof 1 1 0] {1 1}
}
test {WAITAOF master sends PING after last write} {
$master config set repl-ping-replica-period 1
$master incr foo
after 1200 ;# wait for PING
$master get foo
assert_equal [$master waitaof 1 1 0] {1 1}
$master config set repl-ping-replica-period 10
}
test {WAITAOF master client didn't send any write command} {
$master config set repl-ping-replica-period 1
set client [redict_client -1]
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
after 1200 ;# wait for PING
assert_equal [$master waitaof 1 1 0] {1 1}
$client close
$master config set repl-ping-replica-period 10
}
test {WAITAOF master client didn't send any command} {
$master config set repl-ping-replica-period 1
set client [redict [srv -1 "host"] [srv -1 "port"] 0 $::tls]
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
after 1200 ;# wait for PING
assert_equal [$master waitaof 1 1 0] {1 1}
$client close
$master config set repl-ping-replica-period 10
}
foreach fsync {no everysec always} {
test "WAITAOF when replica switches between masters, fsync: $fsync" {
# test a case where a replica is moved from one master to the other
# between two replication streams with different offsets that should
# not be mixed. done to smoke-test race conditions with bio thread.
start_server {overrides {appendonly {yes} auto-aof-rewrite-percentage {0}}} {
start_server {overrides {appendonly {yes} auto-aof-rewrite-percentage {0}}} {
set master2 [srv -1 client]
set master2_host [srv -1 host]
set master2_port [srv -1 port]
set replica2 [srv 0 client]
set replica2_host [srv 0 host]
set replica2_port [srv 0 port]
set replica2_pid [srv 0 pid]
$replica2 replicaof $master2_host $master2_port
wait_for_ofs_sync $master2 $replica2
$master config set appendfsync $fsync
$master2 config set appendfsync $fsync
$replica config set appendfsync $fsync
$replica2 config set appendfsync $fsync
if {$fsync eq "no"} {
after 2000 ;# wait for any previous fsync to finish
# can't afford "no" on the masters
$master config set appendfsync always
$master2 config set appendfsync always
} elseif {$fsync eq "everysec"} {
after 990 ;# hoping to hit a race
}
# add some writes and block a client on each master
set rd [redict_deferring_client -3]
set rd2 [redict_deferring_client -1]
Implementing the WAITAOF command (issue #10505) (#11713) Implementing the WAITAOF functionality which would allow the user to block until a specified number of Redises have fsynced all previous write commands to the AOF. Syntax: `WAITAOF <num_local> <num_replicas> <timeout>` Response: Array containing two elements: num_local, num_replicas num_local is always either 0 or 1 representing the local AOF on the master. num_replicas is the number of replicas that acknowledged the a replication offset of the last write being fsynced to the AOF. Returns an error when called on replicas, or when called with non-zero num_local on a master with AOF disabled, in all other cases the response just contains number of fsync copies. Main changes: * Added code to keep track of replication offsets that are confirmed to have been fsynced to disk. * Keep advancing master_repl_offset even when replication is disabled (and there's no replication backlog, only if there's an AOF enabled). This way we can use this command and it's mechanisms even when replication is disabled. * Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK will be appended only if there's an AOF on the replica, and already ignored on old masters (thus backwards compatible) * WAIT now no longer wait for the replication offset after your last command, but rather the replication offset after your last write (or read command that caused propagation, e.g. lazy expiry). Unrelated changes: * WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI) Implementation details: * Add an atomic var named `fsynced_reploff_pending` that's updated (usually by the bio thread) and later copied to the main `fsynced_reploff` variable (only if the AOF base file exists). I.e. during the initial AOF rewrite it will not be used as the fsynced offset since the AOF base is still missing. * Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific) job that will also update fsync offset the field. * Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio worker thread, to impose ordering on their execution. This solves a race condition where a job could set `fsynced_reploff_pending` to a higher value than another pending fsync job, resulting in indicating an offset for which parts of the data have not yet actually been fsynced. Imposing an ordering on the jobs guarantees that fsync jobs are executed in increasing order of replication offset. * Drain bio jobs when switching `appendfsync` to "always" This should prevent a write race between updates to `fsynced_reploff_pending` in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and those done in the bio thread. * Drain the pending fsync when starting over a new AOF to avoid race conditions with the previous AOF offsets overriding the new one (e.g. after switching to replicate from a new master). * Make sure to update the fsynced offset at the end of the initial AOF rewrite. a must in case there are no additional writes that trigger a periodic fsync, specifically for a replica that does a full sync. Limitations: It is possible to write a module and a Lua script that propagate to the AOF and doesn't propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand. These features are incompatible with the WAITAOF command, and can result in two bad cases. The scenario is that the user executes command that only propagates to AOF, and then immediately issues a WAITAOF, and there's no further writes on the replication stream after that. 1. if the the last thing that happened on the replication stream is a PING (which increased the replication offset but won't trigger an fsync on the replica), then the client would hang forever (will wait for an fack that the replica will never send sine it doesn't trigger any fsyncs). 2. if the last thing that happened is a write command that got propagated properly, then WAITAOF will be released immediately, without waiting for an fsync (since the offset didn't change) Refactoring: * Plumbing to allow bio worker to handle multiple job types This introduces infrastructure necessary to allow BIO workers to not have a 1-1 mapping of worker to job-type. This allows in the future to assign multiple job types to a single worker, either as a performance/resource optimization, or as a way of enforcing ordering between specific classes of jobs. Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 14:26:21 -04:00
$rd set boo 11
$rd2 set boo 22
$rd read
$rd2 read
$rd waitaof 1 1 0
$rd2 waitaof 1 1 0
if {$fsync eq "no"} {
# since appendfsync is disabled in the replicas, the client
# will get released only with full sync
wait_for_blocked_client -1
wait_for_blocked_client -3
}
# switch between the two replicas
$replica2 replicaof $master_host $master_port
$replica replicaof $master2_host $master2_port
assert_equal [$rd read] {1 1}
assert_equal [$rd2 read] {1 1}
$rd close
$rd2 close
assert_equal [$replica get boo] 22
assert_equal [$replica2 get boo] 11
}
}
}
}
}
}
}
start_server {tags {"failover external:skip"}} {
start_server {} {
start_server {} {
set master [srv 0 client]
set master_host [srv 0 host]
set master_port [srv 0 port]
set replica1 [srv -1 client]
set replica1_pid [srv -1 pid]
set replica2 [srv -2 client]
test {setup replication for following tests} {
$replica1 replicaof $master_host $master_port
$replica2 replicaof $master_host $master_port
wait_for_sync $replica1
wait_for_sync $replica2
}
test {WAIT and WAITAOF replica multiple clients unblock - reuse last result} {
set rd [redict_deferring_client]
set rd2 [redict_deferring_client]
$master config set appendonly yes
$replica1 config set appendonly yes
$replica2 config set appendonly yes
$master config set appendfsync always
$replica1 config set appendfsync no
$replica2 config set appendfsync no
waitForBgrewriteaof $master
waitForBgrewriteaof $replica1
waitForBgrewriteaof $replica2
pause_process $replica1_pid
$rd incr foo
$rd read
$rd waitaof 0 1 0
# rd2 has a newer repl_offset
$rd2 incr foo
$rd2 read
$rd2 wait 2 0
wait_for_blocked_clients_count 2
resume_process $replica1_pid
# WAIT will unblock the client first.
assert_equal [$rd2 read] {2}
# Make $replica1 catch up the repl_aof_off, then WAITAOF will unblock the client.
$replica1 config set appendfsync always
$master incr foo
assert_equal [$rd read] {1 1}
$rd ping
assert_equal [$rd read] {PONG}
$rd2 ping
assert_equal [$rd2 read] {PONG}
$rd close
$rd2 close
}
}
}
}