There's a rare case which leads to stagnation in the defragger, causing
it to keep scanning the keyspace and do nothing (not moving any
allocation), this happens when all the allocator slabs of a certain bin
have the same % utilization, but the slab from which new allocations are
made have a lower utilization.
this commit fixes it by removing the current slab from the overall
average utilization of the bin, and also eliminate any precision loss in
the utilization calculation and move the decision about the defrag to
reside inside jemalloc.
and also add a test that consistently reproduce this issue.
with the original version of 6.0.0, this test detects an excessive full
sync.
with the fix in 146201c69, this test detects memory corruption,
especially when using libc allocator with or without valgrind.
Seems like on some systems choosing specific TLS v1/v1.1 versions no
longer works as expected. Test is reduced for v1.2 now which is still
good enough to test the mechansim, and matters most anyway.
This bug was introduced by a recent change in which readQueryFromClient
is using freeClientAsync, and despite the fact that now
freeClientsInAsyncFreeQueue is in beforeSleep, that's not enough since
it's not called during loading in processEventsWhileBlocked.
furthermore, afterSleep was called in that case but beforeSleep wasn't.
This bug also caused slowness sine the level-triggered mode of epoll
kept signaling these connections as readable causing us to keep doing
connRead again and again for ll of these, which keep accumulating.
now both before and after sleep are called, but not all of their actions
are performed during loading, some are only reserved for the main loop.
fixes issue #7215
this test which has coverage for varoius flows of diskless master was
failing randomly from time to time.
the failure was:
[err]: diskless all replicas drop during rdb pipe in tests/integration/replication.tcl
log message of '*Diskless rdb transfer, last replica dropped, killing fork child*' not found
what seemed to have happened is that the master didn't detect that all
replicas dropped by the time the replication ended, it thought that one
replica is still connected.
now the test takes a few seconds longer but it seems stable.
* fix memlry leaks with diskless replica short read.
* fix a few timing issues with valgrind runs
* fix issue with valgrind and watchdog schedule signal
about the valgrind WD issue:
the stack trace test in logging.tcl, has issues with valgrind:
==28808== Can't extend stack to 0x1ffeffdb38 during signal delivery for thread 1:
==28808== too small or bad protection modes
it seems to be some valgrind bug with SA_ONSTACK.
SA_ONSTACK seems unneeded since WD is not recursive (SA_NODEFER was removed),
also, not sure if it's even valid without a call to sigaltstack()
Currently, there are several types of threads/child processes of a
redis server. Sometimes we need deeply optimise the performance of
redis, so we would like to isolate threads/processes.
There were some discussion about cpu affinity cases in the issue:
https://github.com/antirez/redis/issues/2863
So implement cpu affinity setting by redis.conf in this patch, then
we can config server_cpulist/bio_cpulist/aof_rewrite_cpulist/
bgsave_cpulist by cpu list.
Examples of cpulist in redis.conf:
server_cpulist 0-7:2 means cpu affinity 0,2,4,6
bio_cpulist 1,3 means cpu affinity 1,3
aof_rewrite_cpulist 8-11 means cpu affinity 8,9,10,11
bgsave_cpulist 1,10-11 means cpu affinity 1,10,11
Test on linux/freebsd, both work fine.
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Now both master and replicas keep track of the last replication offset
that contains meaningful data (ignoring the tailing pings), and both
trim that tail from the replication backlog, and the offset with which
they try to use for psync.
the implication is that if someone missed some pings, or even have
excessive pings that the promoted replica has, it'll still be able to
psync (avoid full sync).
the downside (which was already committed) is that replicas running old
code may fail to psync, since the promoted replica trims pings form it's
backlog.
This commit adds a test that reproduces several cases of promotions and
demotions with stale and non-stale pings
Background:
The mearningful offset on the master was added recently to solve a problem were
the master is left all alone, injecting PINGs into it's backlog when no one is
listening and then gets demoted and tries to replicate from a replica that didn't
have any of the PINGs (or at least not the last ones).
however, consider this case:
master A has two replicas (B and C) replicating directly from it.
there's no traffic at all, and also no network issues, just many pings in the
tail of the backlog. now B gets promoted, A becomes a replica of B, and C
remains a replica of A. when A gets demoted, it trims the pings from its
backlog, and successfully replicate from B. however, C is still aware of
these PINGs, when it'll disconnect and re-connect to A, it'll ask for something
that's not in the backlog anymore (since A trimmed the tail of it's backlog),
and be forced to do a full sync (something it didn't have to do before the
meaningful offset fix).
Besides that, the psync2 test was always failing randomly here and there, it
turns out the reason were PINGs. Investigating it shows the following scenario:
cycle 1: redis #1 is master, and all the rest are direct replicas of #1
cycle 2: redis #2 is promoted to master, #1 is a replica of #2 and #3 is replica of #1
now we see that when #1 is demoted it prints:
17339:S 21 Apr 2020 11:16:38.523 * Using the meaningful offset 3929963 instead of 3929977 to exclude the final PINGs (14 bytes difference)
17339:S 21 Apr 2020 11:16:39.391 * Trying a partial resynchronization (request e2b3f8817735fdfe5fa4626766daa938b61419e5:3929964).
17339:S 21 Apr 2020 11:16:39.392 * Successful partial resynchronization with master.
and when #3 connects to the demoted #2, #2 says:
17339:S 21 Apr 2020 11:16:40.084 * Partial resynchronization not accepted: Requested offset for secondary ID was 3929978, but I can reply up to 3929964
so the issue here is that the meaningful offset feature saved the day for the
demoted master (since it needs to sync from a replica that didn't get the last
ping), but it didn't help one of the other replicas which did get the last ping.
STRALGO should be a container for mostly read-only string
algorithms in Redis. The algorithms should have two main
characteristics:
1. They should be non trivial to compute, and often not part of
programming language standard libraries.
2. They should be fast enough that it is a good idea to have optimized C
implementations.
Next thing I would love to see? A small strings compression algorithm.
this test is time sensitive and it sometimes fail to pass below the
latency threshold, even on strong machines.
this test was the reson we're running just 2 parallel tests in the
github actions CI, revering this.
