[pgpool-general: 4346] Re: Pgpool - connection hangs in DISCARD ALL

Muhammad Usama m.usama at gmail.com
Fri Jan 22 04:52:43 JST 2016


I am looking into this issue. and unfortunately like Ishii-San I am also
not able to reproduce it. But I found one issue in 3.4 that might cause the
problem. Can you please try the attached patch if it solves the problem.
Also, if the problem still persists, it would be really helpful if you
could share the pgpool-II log.

Best regards
Muhammad Usama

On Fri, Jan 8, 2016 at 12:00 PM, Gerhard Wiesinger <lists at wiesinger.com>

> On 08.01.2016 07:32, Tatsuo Ishii wrote:
>> On 07.01.2016 22:32, Tatsuo Ishii wrote:
>>>> I heard similar reports but problem for developers is, nobody knows
>>>> how to reproduce the hang (a stack trace after the hang is not very
>>>> helpful).
>>>> Yes, there were already 2? on the list.
>>> I can reproduce it randomly in about one day. I think stack traces
>>> should be sufficient when e.g. debug code has been added.
>> No. That's just a consequence of many problems including this one.
>> How to track the bug down?
>>> Debug code?
>>> Enhanced logging?
>> A debug logging would be helpful (start pgpool with -d option) but it
>> will consume huge disk space if you want to save all off them. Is it
>> possible to keep only last 30 minues debug logs before the problem
>> occurs? I guess even 10 minutes is enough to know the cause of the
>> problem.
> Can you try to reproduce it, too?
> My use case is very simple:
> 1.) One persistent connection with username1/database1 doing an insert
> every minute
> 2.) Nagios bombs out about 10 simple SELECT queries every minute with
> username2/database1 nearly at the same time (so it looks like sometimes
> same backend connection can be used)
> So should be easy to test. I close the unused backend connections after
> 2s, so if you bomb e.g. every 10s should be fast to reproduce.
> Happens in my case in 0.5-24h.
> Ciao,
> Gerhard
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diff --git a/src/utils/pool_stream.c b/src/utils/pool_stream.c
index f84d355..4e0297a 100644
--- a/src/utils/pool_stream.c
+++ b/src/utils/pool_stream.c
@@ -211,7 +211,7 @@ int pool_read(POOL_CONNECTION *cp, void *buf, int len)
-                ereport(ERROR,
+                ereport(FRONTEND_ERROR,
 					(errmsg("unable to read data from frontend"),
                          errdetail("socket read failed with an error \"%s\"", strerror(errno))));

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