Re: pg_recvlogical, stdout and SIGHUP

From: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>
To: Andres Freund <andres(at)2ndquadrant(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgreSQL(dot)org>
Subject: Re: pg_recvlogical, stdout and SIGHUP
Date: 2014-05-15 17:09:51
Message-ID: 5374F4DF.2060607@vmware.com
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On 05/15/2014 07:59 PM, Andres Freund wrote:
> On 2014-05-13 17:43:47 +0300, Heikki Linnakangas wrote:
>> On 05/13/2014 04:35 PM, Andres Freund wrote:
>>> On 2014-05-13 16:31:25 +0300, Heikki Linnakangas wrote:
>>>> Another thing I noticed is that if when the output goes to a file, the file
>>>> isn't re-opened immediately on SIGHUP. Only after receiving some data from
>>>> the server. I believe that's also not intentional.
>>>
>>> Hm. I can't really get excited about that one. Not doing that seems to
>>> complicate matters unneccessarily. What's the problem here?
>>
>> Not sure if it matters in any real-world scenario, but I found it pretty
>> surprising while playing with it. It should be trivial to fix; ISTM the
>> problem is that there is a "continue" in the loop when select() is
>> interrupted by signal, but the re-opening is done after the select() in the
>> loop. I think all you need to do is move the check for output_reopen to the
>> beginning of the loop.
>
> Thanks for fixing and sorry for being slow :(.
>
> Any reason you didn't also move the opening of the output file up? It
> seems a bit odd to not have an output file existing every now and
> then...

No particular reason. But that would actually be a great idea, because
currently you won't get any error you give pg_recvlogical an invalid
path, until it receives the first piece of data from the server and
tries to write it to the file. I'll go and do that.

- Heikki

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