[Pgpool-general] unexpected EOF on client connection

[Lonni J Friedman]

On Wed, Sep 14, 2011 at 4:22 PM, Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
>>>> I'm pretty sure that's not the case as the messages stop whenever
>>>> pgpool isn't running, they were not present prior to using pgpool, and
>>>> pg_hba.conf is setup such that the database servers only accept
>>>> connections from each other, and the server running pgpool.  None of
>>>> these servers have normal users connected directly to them (such as
>>>> with ssh), nor are they running anything that would connect to the
>>>> database as a client.  Also, the volume of these messages are such
>>>> that something significant has to be causing them.  Last night, in the
>>>> span of 5 minutes, there were 117 of these messages.
>>>
>>> Ok. I would like to narraow down the reason why we have "unexpected
>>> EOF on client connection" message frequently. I think currently there
>>> are two possiblities:
>>>
>>> 1) pgpool child was killed by some unknown reason(we can omit
>>>   segfault case because you don't see it in the pgpool log)
>>>
>>> 2) pgpool child disconnects to PostgreSQL in ungraceful manner
>>>
>>> For 1) I would like to know if pgpool child process are fine since
>>> they are spawned. Are you seeing any pgpool child process disappeared
>>> since pgpool started?
>>
>> I assume this should be determined by num_init_children (which I've
>> set to 195 in pgpool.conf)?  If so, then I currently have 195
>> processes in either the "wait for connection request" state or
>> actively connected state.
>
> No. Pgpool parent process automatically respawns child process if it's
> dyning. So having num_init_children child process is not showing
> anything usefull. You record 195 process ids and compare current
> process ids. If some of them have been changed, we can assume that
> child process is dying.

Ah, good point.  I just diffed the list of PIDs associated with pgpool
processes before and after another EOF message in the log, and there
were no differences.  So I think that rules out any processes dying?

One other thing that I just noticed from comparing logs between all of
the database servers is that the time stamps for every one of the
'unexpected EOF on client connection' instances are identical.  In
other words, they are happening at the same time on each server.  I
think this further suggests that pgpool has to be doing it?