Thread: postgres 8.4 PQexec hang on HP-UX

Hi All,

I hit a hang issue in postgres 8.4 query. Hit this issue multiple time on H=
P-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 ?

Thanks & Regards,
Devendra Singh

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

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 o=
ther process is holding any lock.
*       We hit this issue multiple times in regression tests but we don't h=
ave any re-producible test case.
*       In last 6-8 moths we hit this 2-3 times. Also we are using the late=
st HP-UX release 1303.
*       Currently we have a system with same state. Let me know what inform=
ation I should collect from that machine.

Thanks & Regards,
Devendra

-----Original Message-----
From: Heikki Linnakangas [mailto:hlinnakangas@vmware.com]
Sent: Saturday, April 13, 2013 1:40 AM
To: Singh, Devendra
Cc: pgsql-bugs@postgresql.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 lon=
g time to execute, or is being blocked trying to acquire a lock that anothe=
r process is holding in the server. You'll have to provide a lot more detai=
ls if you want anyone to make a better guess than that. A simplified test p=
rogram that reproduces the problem would be best.

- Heikki