On 09/05/2012 10:07 PM, Bruce Momjian wrote:
> On Wed, Sep 5, 2012 at 10:04:07PM -0400, Andrew Dunstan wrote:
>> On 09/05/2012 09:42 PM, Bruce Momjian wrote:
>>> On Wed, Sep 5, 2012 at 09:07:05PM -0400, Andrew Dunstan wrote:
>>>>> OK, I worked with Andrew on this issue, and have applied the attached
>>>>> patch which explains what is happening in this case. Andrew's #ifndef
>>>>> WIN32 was the correct fix. I consider this issue closed.
>>>>>
>>>> It looks like we still have problems in this area :-( see
<http://www.pgbuildfarm.org/cgi-bin/show_log.pl?nm=pitta&dt=2012-09-05%2023%3A05%3A16>
>>>>
>>>> Now it looks like somehow the fopen on the log file that isn't
>>>> commented out is failing. But the identical code worked on the same
>>>> machine on HEAD. SO this does rather look like a timing issue.
>>>>
>>>> Investigating ...
>>> Yes, that is very odd. It is also right after the code we just changed
>>> to use binary mode to split the pg_dumpall file, split_old_dump().
>>>
>>> The code is doing pg_ctl -w stop, then starting a new postmaster with
>>> pg_ctl -w start. Looking at the pg_ctl.c code (that you wrote), what
>>> pg_ctl -w stop does is to wait for the postmaster.pid file to disappear,
>>> then it returns complete. I suppose it is possible that the pid file is
>>> getting removed, pg_ctl is returning done, but the pg_ctl binary is
>>> still running, holding open those log files.
>>>
>>> I guess the buildfarm is showing us the problems in pg_upgrade, as it
>>> should. I think you might be right that we need to add a sleep(1) at
>>> the end of stop_postmaster on Windows, and document it is to give the
>>> postmaster time to release its log files.
>>
>>
>> Icky. I wish there were some nice portable flock() mechanism we could use.
>>
>> I just re-ran the test on the same machine, same code, same
>> everything as the reporte3d failure, and it passed, so it definitely
>> looks like it's a timing issue.
>>
>> I'd be inclined to put a loop around that fopen() to try it once
>> every second for, say, 5 seconds.
> Yes, good idea.
>
Suggested patch attached.
cheers
andrew