Re: Possible race condition in pg_basebackup

Hello Shashishekar,

Thank you very much for your review and tests, much appreciated.

Nick

On 18/09/2026 04:02, Shashishekar Hullahally Anantharamu wrote:
> The following review has been posted through the commitfest application:
> make installcheck-world: not tested
> Implements feature: tested, passed
> Spec compliant: not tested
> Documentation: not tested
>
> Hi Andrey and Nick,
>
> I reviewed the v3 two-patch series against PostgreSQL commit 94670ba6d56.
>
> Both patches applied cleanly, and git diff --check reported no errors. I configured the build with assertions, debug support, TAP tests, and injection points enabled. The build completed successfully without warnings or errors.
>
> The implementation moves creation of the WAL-streaming connection and replication slot before the BASE_BACKUP request. It then passes the same connection to StartLogStreamer(). This closes the interval in which the backup startpoint could previously become unprotected before the requested slot was created.
>
> I also reviewed the new 057_basebackup_slot_race.pl test. It deterministically pauses BASE_BACKUP before the startpoint is returned, forces WAL generation and a checkpoint, and verifies that the startpoint segment remains available. The test covers both permanent and temporary replication slots and verifies successful backup completion and slot cleanup.
>
> Test results:
>
> 057_basebackup_slot_race.pl: PASS, 10 tests
> Complete src/bin/pg_basebackup test suite: PASS, 5 files and 351 tests
> Full make check: PASS
>
> The first component-suite and full-check attempts encountered macOS temporary-install Mach-O paths referring to /usr/local/pgsql/lib/libpq.5.dylib. After correcting those paths only in the disposable temporary installation, the affected tests and complete suites passed. This was a local build-environment issue and did not require any source changes.
>
> I did not find any functional or test-coverage issues with the v3 series. The patch appears ready for committer review.
>
> Regards,
> Shashishekar Hullahally Anantharamu
>
> The new status of this patch is: Ready for Committer