Обсуждение: vacuum fails with "could not open statistics file" "Device orresource busy"

Hi,

buildfarm member lorikeet had an interesting buildfarm failure in the
logical decoding test. The failure looks unrelated to logical decoding,
but might be more widely relevant:

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=lorikeet&dt=2018-10-19%2011%3A22%3A34
  VACUUM FULL pg_class;
+ WARNING:  could not open statistics file "pg_stat_tmp/global.stat": Device or resource busy

Now that animal is cygwin based, so maybe it's just some random
weirdness. But ISTM it could also indicate a bug of some sort.

Were it native windows, I'd assume we'd keep a file open with the wrong
flags or such...

Greetings,

Andres Freund

Hi,

On 10/20/2018 04:15 AM, Andres Freund wrote:
> Hi,
> 
> buildfarm member lorikeet had an interesting buildfarm failure in the
> logical decoding test. The failure looks unrelated to logical decoding,
> but might be more widely relevant:
> 
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=lorikeet&dt=2018-10-19%2011%3A22%3A34
>   VACUUM FULL pg_class;
> + WARNING:  could not open statistics file "pg_stat_tmp/global.stat": Device or resource busy
> 
> Now that animal is cygwin based, so maybe it's just some random
> weirdness. But ISTM it could also indicate a bug of some sort.
> 
> Were it native windows, I'd assume we'd keep a file open with the wrong
> flags or such...
> 

Interesting. After a bit more digging, I've found these two places
discussing stats files and "device or resource busy":

[1] https://www.postgresql.org/message-id/flat/51B59794.3000500%40gmail.com

[2]
https://stackoverflow.com/questions/30846804/postgresql-statistics-issue-could-not-rename-temporary-statistics-file

The pgsql-hackers thread is clearly about cygwin (see the diff file).
Not sure about the SO thread, it only talks about 9.4 on windows (but I
guess it's cygwin too).

That being said, I'm not sure how to trigger it - my guess is it happens
when one process holds a file descriptor open while another process
tries to remove it, but I find it strange we'd only seen this twice
since 2013.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

On 10/19/2018 10:15 PM, Andres Freund wrote:
> Hi,
>
> buildfarm member lorikeet had an interesting buildfarm failure in the
> logical decoding test. The failure looks unrelated to logical decoding,
> but might be more widely relevant:
>
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=lorikeet&dt=2018-10-19%2011%3A22%3A34
>    VACUUM FULL pg_class;
> + WARNING:  could not open statistics file "pg_stat_tmp/global.stat": Device or resource busy
>
> Now that animal is cygwin based, so maybe it's just some random
> weirdness. But ISTM it could also indicate a bug of some sort.
>
> Were it native windows, I'd assume we'd keep a file open with the wrong
> flags or such...
>




I have switched the stats_temp_dir of this animal to a Windows Ramdisk. 
Lets' see if the problem persists.

cheers

andrew