Hello all you guys,
Since saturday I'm get stucked in a very strange situation: from time to time (sometimes with intervals less than 10 minutes), the server get "stucked"/"hang" (I dont know how to call it) and every connections on postgres (dont matter if it's SELECT, UPDATE, DELETE, INSERT, startup, authentication...) seems like get "paused"; after some seconds (say ~10 or ~15 sec, sometimes less) everything "goes OK".
So, my first trial was to check disks. Running "iostat" apparently showed that disks was OK. It's a Raid10, 4 600GB SAS, IBM Storage DS3512, over FC. IBM DS Storage Manager says that disks is OK.
Then, memory. Apparently no swap being used:
[###@### data]# free -m
total used free shared buffers cached
Mem: 145182 130977 14204 0 43 121407
-/+ buffers/cache: 9526 135655
Swap: 6143 65 6078
No error on /var/log/messages.
Following, is some strace of one processes, and some others, maybe, useful infos. Every processes I've straced bring the same scenario: seems it get stucked on semop.
There's no modification in server since last monday, that I changed pg_hba.conf to login in LDAP. The LDAP Server apparently is OK, and tcpdump doesnt show any slow on response, neither big activity on this port.
Any help appreciate,
[###@### ~]# strace -ttp 5209
Process 5209 attached - interrupt to quit
09:01:54.122445 semop(2293765, {{15, -1, 0}}, 1) = 0
09:01:55.368785 semop(2293765, {{15, -1, 0}}, 1) = 0
09:01:55.368902 semop(2523148, {{11, 1, 0}}, 1) = 0
09:01:55.368978 semop(2293765, {{15, -1, 0}}, 1) = 0
09:01:55.369861 semop(2293765, {{15, -1, 0}}, 1) = 0
09:01:55.370648 semop(3047452, {{6, 1, 0}}, 1) = 0
09:01:55.370694 semop(2293765, {{15, -1, 0}}, 1) = 0
09:01:55.370762 semop(2785300, {{12, 1, 0}}, 1) = 0
09:01:55.370805 access("base/2048098929", F_OK) = 0
09:01:55.370953 open("base/2048098929/PG_VERSION", O_RDONLY) = 5
[###@### data]# ipcs -l
- Shared Memory Limits -
max number of segments = 4096
max seg size (kbytes) = 83886080
max total shared memory (kbytes) = 17179869184
min seg size (bytes) = 1
------ Semaphore Limits --------
max number of arrays = 128
max semaphores per array = 250
max semaphores system wide = 32000
max ops per semop call = 32
semaphore max value = 32767
------ Messages: Limits --------
max queues system wide = 32768
max size of message (bytes) = 65536
default max size of queue (bytes) = 65536
[###@### data]# ipcs -u
----- Semaphore Status -------
used arrays: 34
allocated semaphores: 546
[###@### data]# uname -a
Linux ### 2.6.32-279.14.1.el6.x86_64 #1 SMP Tue Nov 6 23:43:09 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
postgres=# select version();
version
--------------------------------------------------------------------------------------------------------------
PostgreSQL 9.2.2 on x86_64-unknown-linux-gnu, compiled by gcc (GCC) 4.4.6 20120305 (Red Hat 4.4.6-4), 64-bit
(1 registro)
[###@### data]# cat /etc/redhat-release
CentOS release 6.3 (Final)
