Re: pgstat wait timeout

On 12/28/2011 05:05 AM, Alvaro Herrera wrote:
> Excerpts from Steve Crawford's message of mar dic 27 22:51:06 -0300 2011:
>> I have a system (9.0.4 on Ubuntu Server 10.04 LTS x86_64) that is
>> currently in test/dev mode. I'm currently seeing the following messages
>> occurring every few seconds:
>>
>> ...
>> Dec 27 17:43:22 foo postgres[23693]: [6-1] : WARNING:  pgstat wait timeout
>> Dec 27 17:43:27 foo postgres[27324]: [71400-1] : WARNING:  pgstat wait
>> timeout
>> Dec 27 17:43:33 foo postgres[23695]: [6-1] : WARNING:  pgstat wait timeout
>> Dec 27 17:43:54 foo postgres[27324]: [71401-1] : WARNING:  pgstat wait
>> timeout
> Hm, so can you strace the stats collector to see what it's doing?  Maybe
> grab a backtrace with GDB from it before anything else.
>
> My guess is 27324 is the autovac launcher and the others are autovac
> workers just as they die.
>
You are correct. 27324 is the launcher and the others are autovac 
workers. Here's the strace of the stats collector process:

getppid()                               = 27320
poll([{fd=8, events=POLLIN|POLLERR}], 1, 2000) = 0 (Timeout)
getppid()                               = 27320
poll([{fd=8, events=POLLIN|POLLERR}], 1, 2000) = 0 (Timeout)
getppid()                               = 27320
poll([{fd=8, events=POLLIN|POLLERR}], 1, 2000) = 0 (Timeout)
....rinse...lather...repeat...ad nauseum...

And the backtrace:

#0  0x00007ff4d2e80f58 in poll () from /lib/libc.so.6
#1  0x00007ff4d4e6f465 in ?? ()
#2  0x00007ff4d4e6fd83 in pgstat_start ()
#3  0x00007ff4d4e73475 in ?? ()
#4 <signal handler called>
#5  0x00007ff4d2e85fd3 in select () from /lib/libc.so.6
#6  0x00007ff4d4e71b93 in ?? ()
#7  0x00007ff4d4e74b01 in PostmasterMain ()
#8  0x00007ff4d4e193b3 in main ()

Cheers,
Steve