Re: BackgroundPsql swallowing errors on windows

On 2026-02-18 We 2:41 PM, Andrew Dunstan wrote:
>
> On 2026-02-17 Tu 4:56 PM, Andres Freund wrote:
>> Hi,
>>
>> On 2026-02-17 16:31:02 -0500, Andrew Dunstan wrote:
>>> On 2026-02-16 Mo 7:17 PM, Andres Freund wrote:
>>>> I briefly tried this out. The overall resource usage of the test is 
>>>> noticeably
>>>> reduced - and that's on linux with fast fork, so it should be 
>>>> considerably
>>>> better on windows.  However, the tests take a lot longer than 
>>>> before, I think
>>>> mostly due to polling for results rather than waiting for them to 
>>>> be ready
>>>> using PQsocketPoll() or such.
>>>>
>>>> E.g. bloom/001_wal takes about 15s on HEAD for me, but 138s with 
>>>> the patch. I
>>>> think that's just due to the various usleep(100_000);
>>>>
>>>>
>>>> FWIW, oauth_validator/001_server fails with the patch at the moment.
>>>>
>>> Try this version. On my machine it's now a few percent faster. I 
>>> fixed the
>>> polling. I also added pipeline support for large sets of commands, to
>>> minimize roundtrips.
>> Nice!  Will try it out.
>>
>>
>> Have you tried it on windows already? That's where we pay by far the 
>> biggest
>> price due to all the unnecessary process creations...
>>
>> It looks like strawberry perl has FFI::Platypus, but not FFI::C.  
>> There is
>> perl/vendor/lib/FFI/Platypus/Lang/C.pm, but that just seems like it's
>> documentation.  There is however FFI::Platypus::Record, which maybe 
>> could
>> suffice?
>>
>> Do we actually need FFI::C, or can we work around not having it? 
>> Looks like
>> it's just used for notify related stuff.
>>
>> It looks like mingw doesn't have packages for FFI::Platypus, but it'll
>> probably be a lot easier to build that than when using msvc.
>>
>>
>
> I replaced the use of FFI::C with FFI::Platypus::Record. That comes 
> for free with FFI::Platypus, so there would be no extra dependency. It 
> means a little extra housekeeping so we don't lose track of the 
> pointer for later use with PQfreemem, but it's not too bad.
>
> I have tried it out with Windows, seemed to work OK although the 
> xid_wraparound tests 2 and 3 timed out.
>
> Latest is attached.
>
>
>

Here is v12. I removed the XS variant in this version, which makes 
things simpler. We can restore it if necessary.

Patch 1 adds the new framework

Patch 2 adapts Cluster.pm to it, as well as handling some instability at 
global destruction time that was exacerbated by using FFI::Platypus.

Patch 3 makes improvements in the individual TAP tests using the 
framework, including removing every one of the calls to background_psql().


I'm going to add this to the CF and will start testing (again) on Windows.


cheers


andrew


--
Andrew Dunstan
EDB: https://www.enterprisedb.com