I saw that the new defag test for list was failing in CI recently, so i
reduce it's threshold from 12 to 60.
besides that, i add / improve the latency test for that other two defrag
tests (add a sensitive latency and digest / save checks)
and fix bad usage of debug populate (can't overrides existing keys).
this was the original intention, which creates higher fragmentation.
When active defrag kicks in and finds a big list, it will create a bookmark to
a node so that it is able to resume iteration from that node later.
The quicklist manages that bookmark, and updates it in case that node is deleted.
This will increase memory usage only on lists of over 1000 (see
active-defrag-max-scan-fields) quicklist nodes (1000 ziplists, not 1000 items)
by 16 bytes.
In 32 bit build, this change reduces the maximum effective config of
list-compress-depth and list-max-ziplist-size (from 32767 to 8191)
Few tests had borderline thresholds that were adjusted.
The slave buffers test had two issues, preventing the slave buffer from growing:
1) the slave didn't necessarily go to sleep on time, or woke up too early,
now using SIGSTOP to make sure it goes to sleep exactly when we want.
2) the master disconnected the slave on timeout
on slower machines, the active defrag test tended to fail.
although the fragmentation ratio was below the treshold, the defragger was
still in the middle of a scan cycle.
this commit changes:
- the defragger uses the current fragmentation state, rather than the cache one
that is updated by server cron every 100ms. this actually fixes a bug of
starting one excess scan cycle
- the test lets the defragger use more CPU cycles, in hope that the defrag
will be faster, but also give it more time before we give up.
problems fixed:
* failing to read fragmentation information from jemalloc
* overflow in jemalloc fragmentation hint to the defragger
* test suite not triggering eviction after population
other fixes / improvements:
- LUA script memory isn't taken from zmalloc (taken from libc malloc)
so it can cause high fragmentation ratio to be displayed (which is false)
- there was a problem with "fragmentation" info being calculated from
RSS and used_memory sampled at different times (now sampling them together)
other details:
- adding a few more allocator info fields to INFO and MEMORY commands
- improve defrag test to measure defrag latency of big keys
- increasing the accuracy of the defrag test (by looking at real grag info)
this way we can use an even lower threshold and still avoid false positives
- keep the old (total) "fragmentation" field unchanged, but add new ones for spcific things
- add these the MEMORY DOCTOR command
- deduct LUA memory from the rss in case of non jemalloc allocator (one for which we don't "allocator active/used")
- reduce sampling rate of the rss and allocator info
Apparently 1.4 is too low compared to what you get in certain setups
(including mine). I raised it to 1.55 that hopefully is still enough to
test that the fragmentation went down from 1.7 but without incurring in
issues, however the test setup may be still fragile so certain times this
may lead to false positives again, it's hard to test for these things
in a determinsitic way.
Related to #3786.
This test on Linux was extremely slow, since in Tcl we can't enable
easily tcp-nodelay, so the busy loop used to take *a lot* with bigger
writes. Fixed using pipelining.
