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Re: pgAgent crashes on failed connection

From: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
To: Merlin Moncure <mmoncure(at)gmail(dot)com>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Dave Page <dpage(at)pgadmin(dot)org>, pgadmin-hackers <pgadmin-hackers(at)postgresql(dot)org>
Subject: Re: pgAgent crashes on failed connection
Date: 2011-09-28 20:32:12
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgadmin-hackers
On 28.09.2011 20:24, Merlin Moncure wrote:
> On Wed, Sep 28, 2011 at 2:16 PM, Heikki Linnakangas
> <heikki(dot)linnakangas(at)enterprisedb(dot)com>  wrote:
>> (sorry for the late reply, this fell through the cracks..)
>> On 10.08.2011 11:48, Dave Page wrote:
>>> On Thu, Aug 4, 2011 at 8:30 PM, Merlin Moncure<mmoncure(at)gmail(dot)com>    wrote:
>>>> On Thu, Aug 4, 2011 at 2:19 PM, Heikki Linnakangas
>>>> <heikki(dot)linnakangas(at)enterprisedb(dot)com>    wrote:
>>>>> I created 100 identical pgagent jobs, with one step that simply does
>>>>> "SELECT
>>>>> pg_sleep(10)". I then forced them all to run immediately, with "UPDATE
>>>>> pgagent.pga_job SET jobnextrun=now();". pgagent crashed.
>>>>> What happened is that the when all those jobs are launched at the same
>>>>> time,
>>>>> the server ran into the max_connections limit, and pgagent didn't handle
>>>>> that too well. JobThread::JobThread constructor does not check for NULL
>>>>> result from DBConn::Get(), and passes a NULL connection to Job::Job,
>>>>> which
>>>>> tries to reference it, leading to a segfault.
>>>>> I propose the attached patch.
>>>> hm, in the event that happens, is that logged in the client somehow?
>>>> wouldn't you want to throw an exception or something like that?
>>> I think the most straightforward way to handle this is to dump an
>>> error into pgagent.pga_joblog when deleting the thread. Might be a
>>> little ugly to pass the original error message back rather than a
>>> generic one though. Can you take a look Heikki?
>> You mean something like the attached? Works for me, but inserting an entry
>> in joblog for each failed attempt might create a lot of entries there, if
>> the problem persists.
> Is it correct behavior to throw unhandled sql exception if the logging
> query fails?

Sorry, I didn't understand that. I don't see any exceptions been thrown.

   Heikki Linnakangas

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Subject: pgAgent commit: More cleanly handle cases when the databaseconnection
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