It also causes relay-log corruptions. For instance, how can a syntax error make it into replication, the reason is mysql-5.0.51 is truncating the stream.
The only work around is to rebuild the relay log.
The BUG is listed here for replication problems. I suspected IO_CACHE corruption as the cause.
update: this is the cause of the huge blocks
InnoDB: Warning: a long semaphore wait:
--Thread 1173899616 has waited at btr0cur.c line 424 for 292.00 seconds the semaphore:
S-lock on RW-latch at 0x2df5159f58 created in file buf0buf.c line 497
a writer (thread id 1173899616) has reserved it in mode exclusive
number of readers 0, waiters flag 1
Last time read locked in file btr0cur.c line 424
Last time write locked in file buf0buf.c line 1768
InnoDB: Warning: a long semaphore wait:
--Thread 1172302176 has waited at btr0cur.c line 424 for 295.00 seconds the semaphore:
S-lock on RW-latch at 0x2df50706a8 created in file buf0buf.c line 497
a writer (thread id 1172302176) has reserved it in mode exclusive
number of readers 0, waiters flag 1
Last time read locked in file btr0cur.c line 424
Last time write locked in file buf0buf.c line 1768
InnoDB: Warning: a long semaphore wait:
--Thread 1182951776 has waited at trx0trx.c line 1627 for 283.00 seconds the semaphore:
Mutex at 0x2a9eac52b8 created file srv0srv.c line 872, lock var 0
waiters flag 0
InnoDB: ###### Starts InnoDB Monitor for 30 secs to print diagnostic info:
InnoDB: Pending preads 1, pwrites 0
Additionally mySQL is putting self in swap for a memory config that has not changed from my previous version.
I'm thinking that there is some memory leak in 5.0.51
6 comments:
Could you please be a little bit more specific about the "huge blocking locks"?
So these locking problems seem to be InnoDB-specifc. Thanks!
We also experienced the relay log corruptions with high I/O and load, and also that it had the tendency to crash MySQL. One good thing about 5.0.54 is that this bug is fixed:
http://bugs.mysql.com/bug.php?id=31793
However, we still have a script to automatically reset replication and start the slave threads anew.
The relay log corruption bug is still open in 5.0.54. See http://bugs.mysql.com/bug.php?id=26489. Most of the time, doing 'stop slave, reset slave, change master to the SQL thread position' is sufficient to fix the corruption.
I don't understand the blocking problem that you mention. We have intermittent long lock waits on the adaptive hash index latch (the lock holder doesn't release it while doing something that take a long time -- like sorting). This can be fixed by adding calls in a few places to release the latch. Is that your problem?
I am using 5.0.37 now and hope to upgrade to 5.0.54.
try
innodb_adaptive_hash_index = 0
(5.0.52 or higher)
This should fix the locking issues. The slave / relay log corruption is a different issue, not sure what version the fix is making it into, but likely not in 5.0.54.
Dathan, there is 1 known memory leak, which is to do with index_merge queries. Please check if this bug is relevant: http://bugs.mysql.com/bug.php?id=27732
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