Re: parallel restore vs. windows

Andrew Dunstan <andrew@dunslane.net>

From: Andrew Dunstan <andrew@dunslane.net>
To: Andrew Chernow <ac@esilo.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2008-12-09T17:36:40Z
Lists: pgsql-hackers

Andrew Chernow wrote:
>>
>> Parts of AH need deep cloning, notably the formatData member, which 
>> is done in _ReopenArchive().
>>
>
> Is it okay to clone this from within the thread?

I don't see why not.

>
> The reopen() appears to mess with AH->FH, which mutltiple threads are 
> calling fclose on.  The second thread is going to fail and the first 
> fclose() will close the main threads handle.
>
> + #ifndef WIN32
> +     if (fclose(AH->FH) != 0)
> +         die_horribly(AH, modulename, "could not close archive file: 
> %s\n",
> +                      strerror(errno));
> + #else
>
> How are things failing?  Core dump, maybe you are seeing the above 
> error?  The non-windows path is safe from this because a) it never 
> does an fclose and b) its a fork and has its own copy of the FH.

No, as this fragment shows, fclose() is NOT called on Windows.

The program dies with a nasty dialog box when restoring a dump of the 
regression database after the second COPY thread disconnects.

cheers

andrew