Re: postgres 8.4 PQexec hang on HP-UX

Hi Heikki,

Thanks for looking into this issue. My observations on this issue are below:-
* I verified that process is in deadlock since last 4-5 days and no other process is holding any lock.
* We hit this issue multiple times in regression tests but we don't have any re-producible test case.
* In last 6-8 moths we hit this 2-3 times. Also we are using the latest HP-UX release 1303.
* Currently we have a system with same state. Let me know what information I should collect from that machine.

Thanks & Regards,
Devendra

-----Original Message-----
From: Heikki Linnakangas [mailto:hlinnakangas(at)vmware(dot)com]
Sent: Saturday, April 13, 2013 1:40 AM
To: Singh, Devendra
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: [BUGS] postgres 8.4 PQexec hang on HP-UX

On 12.04.2013 09:41, Singh, Devendra wrote:
> Hi All,
>
> I hit a hang issue in postgres 8.4 query. Hit this issue multiple time on HP-UX. Below is the snapshot of the hang thread.
>
> -------------------------------- lwpid : 600943 -------------------------------
> 0: c00000000054ced0 : _poll_sys() + 0x30 (/usr/lib/hpux64/libc.so.1)
> 1: c000000000561560 : poll() + 0xe0 (/usr/lib/hpux64/libc.so.1)
> 2: c000000001f798e0 : pqSocketPoll() at fe-misc.c:1079
> 3: c000000001f790e0 : pqWait() at fe-misc.c:1024
> 4: c000000001f6ebb0 : PQgetResult() at fe-exec.c:1554
> 5: c000000001f6f0a0 : PQexec() at fe-exec.c:1735
>
> Is it a known issue? Any possible workaround ?

The first thing that comes to mind is that the query is simply taking a long time to execute, or is being blocked trying to acquire a lock that another process is holding in the server. You'll have to provide a lot more details if you want anyone to make a better guess than that. A simplified test program that reproduces the problem would be best.

- Heikki