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10 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
guybe7
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4ba47d2d21
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Add reply_schema to command json files (internal for now) (#10273)
Work in progress towards implementing a reply schema as part of COMMAND DOCS, see #9845 Since ironing the details of the reply schema of each and every command can take a long time, we would like to merge this PR when the infrastructure is ready, and let this mature in the unstable branch. Meanwhile the changes of this PR are internal, they are part of the repo, but do not affect the produced build. ### Background In #9656 we add a lot of information about Redis commands, but we are missing information about the replies ### Motivation 1. Documentation. This is the primary goal. 2. It should be possible, based on the output of COMMAND, to be able to generate client code in typed languages. In order to do that, we need Redis to tell us, in detail, what each reply looks like. 3. We would like to build a fuzzer that verifies the reply structure (for now we use the existing testsuite, see the "Testing" section) ### Schema The idea is to supply some sort of schema for the various replies of each command. The schema will describe the conceptual structure of the reply (for generated clients), as defined in RESP3. Note that the reply structure itself may change, depending on the arguments (e.g. `XINFO STREAM`, with and without the `FULL` modifier) We decided to use the standard json-schema (see https://json-schema.org/) as the reply-schema. Example for `BZPOPMIN`: ``` "reply_schema": { "oneOf": [ { "description": "Timeout reached and no elements were popped.", "type": "null" }, { "description": "The keyname, popped member, and its score.", "type": "array", "minItems": 3, "maxItems": 3, "items": [ { "description": "Keyname", "type": "string" }, { "description": "Member", "type": "string" }, { "description": "Score", "type": "number" } ] } ] } ``` #### Notes 1. It is ok that some commands' reply structure depends on the arguments and it's the caller's responsibility to know which is the relevant one. this comes after looking at other request-reply systems like OpenAPI, where the reply schema can also be oneOf and the caller is responsible to know which schema is the relevant one. 2. The reply schemas will describe RESP3 replies only. even though RESP3 is structured, we want to use reply schema for documentation (and possibly to create a fuzzer that validates the replies) 3. For documentation, the description field will include an explanation of the scenario in which the reply is sent, including any relation to arguments. for example, for `ZRANGE`'s two schemas we will need to state that one is with `WITHSCORES` and the other is without. 4. For documentation, there will be another optional field "notes" in which we will add a short description of the representation in RESP2, in case it's not trivial (RESP3's `ZRANGE`'s nested array vs. RESP2's flat array, for example) Given the above: 1. We can generate the "return" section of all commands in [redis-doc](https://redis.io/commands/) (given that "description" and "notes" are comprehensive enough) 2. We can generate a client in a strongly typed language (but the return type could be a conceptual `union` and the caller needs to know which schema is relevant). see the section below for RESP2 support. 3. We can create a fuzzer for RESP3. ### Limitations (because we are using the standard json-schema) The problem is that Redis' replies are more diverse than what the json format allows. This means that, when we convert the reply to a json (in order to validate the schema against it), we lose information (see the "Testing" section below). The other option would have been to extend the standard json-schema (and json format) to include stuff like sets, bulk-strings, error-string, etc. but that would mean also extending the schema-validator - and that seemed like too much work, so we decided to compromise. Examples: 1. We cannot tell the difference between an "array" and a "set" 2. We cannot tell the difference between simple-string and bulk-string 3. we cannot verify true uniqueness of items in commands like ZRANGE: json-schema doesn't cover the case of two identical members with different scores (e.g. `[["m1",6],["m1",7]]`) because `uniqueItems` compares (member,score) tuples and not just the member name. ### Testing This commit includes some changes inside Redis in order to verify the schemas (existing and future ones) are indeed correct (i.e. describe the actual response of Redis). To do that, we added a debugging feature to Redis that causes it to produce a log of all the commands it executed and their replies. For that, Redis needs to be compiled with `-DLOG_REQ_RES` and run with `--reg-res-logfile <file> --client-default-resp 3` (the testsuite already does that if you run it with `--log-req-res --force-resp3`) You should run the testsuite with the above args (and `--dont-clean`) in order to make Redis generate `.reqres` files (same dir as the `stdout` files) which contain request-response pairs. These files are later on processed by `./utils/req-res-log-validator.py` which does: 1. Goes over req-res files, generated by redis-servers, spawned by the testsuite (see logreqres.c) 2. For each request-response pair, it validates the response against the request's reply_schema (obtained from the extended COMMAND DOCS) 5. In order to get good coverage of the Redis commands, and all their different replies, we chose to use the existing redis test suite, rather than attempt to write a fuzzer. #### Notes about RESP2 1. We will not be able to use the testing tool to verify RESP2 replies (we are ok with that, it's time to accept RESP3 as the future RESP) 2. Since the majority of the test suite is using RESP2, and we want the server to reply with RESP3 so that we can validate it, we will need to know how to convert the actual reply to the one expected. - number and boolean are always strings in RESP2 so the conversion is easy - objects (maps) are always a flat array in RESP2 - others (nested array in RESP3's `ZRANGE` and others) will need some special per-command handling (so the client will not be totally auto-generated) Example for ZRANGE: ``` "reply_schema": { "anyOf": [ { "description": "A list of member elements", "type": "array", "uniqueItems": true, "items": { "type": "string" } }, { "description": "Members and their scores. Returned in case `WITHSCORES` was used.", "notes": "In RESP2 this is returned as a flat array", "type": "array", "uniqueItems": true, "items": { "type": "array", "minItems": 2, "maxItems": 2, "items": [ { "description": "Member", "type": "string" }, { "description": "Score", "type": "number" } ] } } ] } ``` ### Other changes 1. Some tests that behave differently depending on the RESP are now being tested for both RESP, regardless of the special log-req-res mode ("Pub/Sub PING" for example) 2. Update the history field of CLIENT LIST 3. Added basic tests for commands that were not covered at all by the testsuite ### TODO - [x] (maybe a different PR) add a "condition" field to anyOf/oneOf schemas that refers to args. e.g. when `SET` return NULL, the condition is `arguments.get||arguments.condition`, for `OK` the condition is `!arguments.get`, and for `string` the condition is `arguments.get` - https://github.com/redis/redis/issues/11896 - [x] (maybe a different PR) also run `runtest-cluster` in the req-res logging mode - [x] add the new tests to GH actions (i.e. compile with `-DLOG_REQ_RES`, run the tests, and run the validator) - [x] (maybe a different PR) figure out a way to warn about (sub)schemas that are uncovered by the output of the tests - https://github.com/redis/redis/issues/11897 - [x] (probably a separate PR) add all missing schemas - [x] check why "SDOWN is triggered by misconfigured instance replying with errors" fails with --log-req-res - [x] move the response transformers to their own file (run both regular, cluster, and sentinel tests - need to fight with the tcl including mechanism a bit) - [x] issue: module API - https://github.com/redis/redis/issues/11898 - [x] (probably a separate PR): improve schemas: add `required` to `object`s - https://github.com/redis/redis/issues/11899 Co-authored-by: Ozan Tezcan <ozantezcan@gmail.com> Co-authored-by: Hanna Fadida <hanna.fadida@redislabs.com> Co-authored-by: Oran Agra <oran@redislabs.com> Co-authored-by: Shaya Potter <shaya@redislabs.com> |
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Oran Agra
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c8226ae378
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Try to solve valgrind CI test error with client-eviction test (#11822)
The test sporadically failed with valgrind trying to match `no client named obuf-client1 found*` in the log it looks like `obuf-client1` was indeed dropped, so i'm guessing it's because CLIENT LIST was processed first. |
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Binbin
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cd58af4d7f
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Speed up test: client evicted due to client tracking prefixes (#11823)
We noticed that `client evicted due to client tracking prefixes` takes over 200 seconds with valgrind. We combine three prefixes in each command, this will probably save us half the testing time. Before: normal: 3508ms, valgrind: 289503ms -> 290s With three prefixes, normal: 1500ms, valgrind: 135742ms -> 136s Since we did not actually count the memory usage of all prefixes, see getClientMemoryUsage, so we can not use larger prefixes to speed up the test here. Also this PR cleaned up some spaces (IDE jobs) and typos. |
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Harkrishn Patro
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c0267b3fa5
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Optimize client memory usage tracking operation while client eviction is disabled (#11348)
## Issue During the client input/output buffer processing, the memory usage is incrementally updated to keep track of clients going beyond a certain threshold `maxmemory-clients` to be evicted. However, this additional tracking activity leads to unnecessary CPU cycles wasted when no client-eviction is required. It is applicable in two cases. * `maxmemory-clients` is set to `0` which equates to no client eviction (applicable to all clients) * `CLIENT NO-EVICT` flag is set to `ON` which equates to a particular client not applicable for eviction. ## Solution * Disable client memory usage tracking during the read/write flow when `maxmemory-clients` is set to `0` or `client no-evict` is `on`. The memory usage is tracked only during the `clientCron` i.e. it gets periodically updated. * Cleanup the clients from the memory usage bucket when client eviction is disabled. * When the maxmemory-clients config is enabled or disabled at runtime, we immediately update the memory usage buckets for all clients (tested scanning 80000 took some 20ms) Benchmark shown that this can improve performance by about 5% in certain situations. Co-authored-by: Oran Agra <oran@redislabs.com> |
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Harkrishn Patro
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0ab885a685
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Account sharded pubsub channels memory consumption (#10925)
Account sharded pubsub channels memory consumption in client memory usage computation to accurately evict client based on the set threshold for `maxmemory-clients`. |
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ranshid
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9b15dd288e
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Introduce debug command to disable reply buffer resizing (#10360)
In order to resolve some flaky tests which hard rely on examine memory footprint. we introduce the following fixes: # Fix in client-eviction test - by @yoav-steinberg Sometime the libc allocator can use different size client struct allocations. this may cause unexpected memory calculations to fail the test. # Introduce new DEBUG command for disabling reply buffer resizing In order to eliminate reply buffer resizing during specific tests. we introduced the ability to disable (and enable) the resizing cron job Co-authored-by: yoav-steinberg yoav@redislabs.com |
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ranshid
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5860fa3d9c
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deflake client-eviction test "evict clients only until below limit" (#10354)
After introducing #9822 need to prevent client reply buffer shrink to maintain correct client memory math. add needs:debug missing one one test. Co-authored-by: Oran Agra <oran@redislabs.com> |
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ranshid
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47c51d0c78
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introduce dynamic client reply buffer size - save memory on idle clients (#9822)
Current implementation simple idle client which serves no traffic still
use ~17Kb of memory. this is mainly due to a fixed size reply buffer
currently set to 16kb.
We have encountered some cases in which the server operates in a low memory environments.
In such cases a user who wishes to create large connection pools to support potential burst period,
will exhaust a large amount of memory to maintain connected Idle clients.
Some users may choose to "sacrifice" performance in order to save memory.
This commit introduce a dynamic mechanism to shrink and expend the client reply buffer based on
periodic observed peak.
the algorithm works as follows:
1. each time a client reply buffer has been fully written, the last recorded peak is updated:
new peak = MAX( last peak, current written size)
2. during clients cron we check for each client if the last observed peak was:
a. matching the current buffer size - in which case we expend (resize) the buffer size by 100%
b. less than half the buffer size - in which case we shrink the buffer size by 50%
3. In any case we will **not** resize the buffer in case:
a. the current buffer peak is less then the current buffer usable size and higher than 1/2 the
current buffer usable size
b. the value of (current buffer usable size/2) is less than 1Kib
c. the value of (current buffer usable size*2) is larger than 16Kib
4. the peak value is reset to the current buffer position once every **5** seconds. we maintain a new
field in the client structure (buf_peak_last_reset_time) which is used to keep track of how long it
passed since the last buffer peak reset.
### **Interface changes:**
**CIENT LIST** - now contains 2 new extra fields:
rbs= < the current size in bytes of the client reply buffer >
rbp=< the current value in bytes of the last observed buffer peak position >
**INFO STATS** - now contains 2 new statistics:
reply_buffer_shrinks = < total number of buffer shrinks performed >
reply_buffer_expends = < total number of buffer expends performed >
Co-authored-by: Oran Agra <oran@redislabs.com>
Co-authored-by: Yoav Steinberg <yoav@redislabs.com>
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yoav-steinberg
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6600253046
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Client eviction ci issues (#9549)
Fixing CI test issues introduced in #8687 - valgrind warnings in readQueryFromClient when client was freed by processInputBuffer - adding DEBUG pause-cron for tests not to be time dependent. - skipping a test that depends on socket buffers / events not compatible with TLS - making sure client got subscribed by not using deferring client |
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yoav-steinberg
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2753429c99
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Client eviction (#8687)
### Description A mechanism for disconnecting clients when the sum of all connected clients is above a configured limit. This prevents eviction or OOM caused by accumulated used memory between all clients. It's a complimentary mechanism to the `client-output-buffer-limit` mechanism which takes into account not only a single client and not only output buffers but rather all memory used by all clients. #### Design The general design is as following: * We track memory usage of each client, taking into account all memory used by the client (query buffer, output buffer, parsed arguments, etc...). This is kept up to date after reading from the socket, after processing commands and after writing to the socket. * Based on the used memory we sort all clients into buckets. Each bucket contains all clients using up up to x2 memory of the clients in the bucket below it. For example up to 1m clients, up to 2m clients, up to 4m clients, ... * Before processing a command and before sleep we check if we're over the configured limit. If we are we start disconnecting clients from larger buckets downwards until we're under the limit. #### Config `maxmemory-clients` max memory all clients are allowed to consume, above this threshold we disconnect clients. This config can either be set to 0 (meaning no limit), a size in bytes (possibly with MB/GB suffix), or as a percentage of `maxmemory` by using the `%` suffix (e.g. setting it to `10%` would mean 10% of `maxmemory`). #### Important code changes * During the development I encountered yet more situations where our io-threads access global vars. And needed to fix them. I also had to handle keeps the clients sorted into the memory buckets (which are global) while their memory usage changes in the io-thread. To achieve this I decided to simplify how we check if we're in an io-thread and make it much more explicit. I removed the `CLIENT_PENDING_READ` flag used for checking if the client is in an io-thread (it wasn't used for anything else) and just used the global `io_threads_op` variable the same way to check during writes. * I optimized the cleanup of the client from the `clients_pending_read` list on client freeing. We now store a pointer in the `client` struct to this list so we don't need to search in it (`pending_read_list_node`). * Added `evicted_clients` stat to `INFO` command. * Added `CLIENT NO-EVICT ON|OFF` sub command to exclude a specific client from the client eviction mechanism. Added corrosponding 'e' flag in the client info string. * Added `multi-mem` field in the client info string to show how much memory is used up by buffered multi commands. * Client `tot-mem` now accounts for buffered multi-commands, pubsub patterns and channels (partially), tracking prefixes (partially). * CLIENT_CLOSE_ASAP flag is now handled in a new `beforeNextClient()` function so clients will be disconnected between processing different clients and not only before sleep. This new function can be used in the future for work we want to do outside the command processing loop but don't want to wait for all clients to be processed before we get to it. Specifically I wanted to handle output-buffer-limit related closing before we process client eviction in case the two race with each other. * Added a `DEBUG CLIENT-EVICTION` command to print out info about the client eviction buckets. * Each client now holds a pointer to the client eviction memory usage bucket it belongs to and listNode to itself in that bucket for quick removal. * Global `io_threads_op` variable now can contain a `IO_THREADS_OP_IDLE` value indicating no io-threading is currently being executed. * In order to track memory used by each clients in real-time we can't rely on updating these stats in `clientsCron()` alone anymore. So now I call `updateClientMemUsage()` (used to be `clientsCronTrackClientsMemUsage()`) after command processing, after writing data to pubsub clients, after writing the output buffer and after reading from the socket (and maybe other places too). The function is written to be fast. * Clients are evicted if needed (with appropriate log line) in `beforeSleep()` and before processing a command (before performing oom-checks and key-eviction). * All clients memory usage buckets are grouped as follows: * All clients using less than 64k. * 64K..128K * 128K..256K * ... * 2G..4G * All clients using 4g and up. * Added client-eviction.tcl with a bunch of tests for the new mechanism. * Extended maxmemory.tcl to test the interaction between maxmemory and maxmemory-clients settings. * Added an option to flag a numeric configuration variable as a "percent", this means that if we encounter a '%' after the number in the config file (or config set command) we consider it as valid. Such a number is store internally as a negative value. This way an integer value can be interpreted as either a percent (negative) or absolute value (positive). This is useful for example if some numeric configuration can optionally be set to a percentage of something else. Co-authored-by: Oran Agra <oran@redislabs.com> |