Re: pg_recvlogical: Prevent flushed data from being re-sent after restarting replication

[Fujii Masao]

On Mon, Dec 29, 2025 at 9:45 PM Mircea Cadariu <cadariu.mir...@gmail.com> wrote:
>
> Hi,
>
> Thanks for the patch updates.
>
> On 26/12/2025 10:28, Fujii Masao wrote:
>
> Maybe it's better to use slurp_file(). We already have wait_for_log() to
> wait for a message in the cluster's log file, but there's no helper function
> to wait for specific content to appear in an arbitrary file.
>
> To support waiting for output in pg_recvlogical's output file,
> I added a new helper that uses slurp_file() (see the attached 0002 patch).
> I also updated the 0003 patch (the pg_recvlogical reconnection test) to
> use this helper instead of pg_read_file(). Thoughts?
>
> Agreed, nice addition.
>
> I applied the v3-000* patch set and it builds successfully and passes the 
> tests on my laptop.
>
> However the CI seems not completely happy yet, with previous 2 runs not green 
> for Windows. Could it be there's an issue with executing the test on Windows?

Thanks for the report!

The TAP test failed on Windows because it attempted to terminate
pg_recvlogical using a TERM signal, which isn't available there.
As a result, the test waited indefinitely for pg_recvlogical to exit
and finally timed out.

To address this, I updated the 0003 patch so that the test passes
--endpos to pg_recvlogical on Windows only. This allows pg_recvlogical
to terminate without signals, by generating WAL until the current
position reaches the specified end position. OTOH, on non-Windows
platforms, the test continues to use signals to terminate pg_recvlogical.

This approach may be somewhat unstable. If there's a more robust
way to terminate pg_recvlogical on Windows, I'd be happy to switch
to it, but I couldn't come up with a better option.

Updated patches are attached.

Regards,

-- 
Fujii Masao

v4-0004-pg_recvlogical-remove-unnecessary-OutputFsync-ret.patch
Description: Binary data

v4-0003-Add-test-for-pg_recvlogical-reconnection-behavior.patch
Description: Binary data

v4-0001-pg_recvlogical-Prevent-flushed-data-from-being-re.patch
Description: Binary data

v4-0002-Add-a-new-helper-function-wait_for_file-to-Utils..patch
Description: Binary data