Horton

Re: Backup command and functions can cause assertion failure and segmentation fault

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Fujii Masao <masao.fujii@oss.nttdata.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2022-07-07T00:09:35Z
Lists: pgsql-hackers 
On Wed, Jul 06, 2022 at 11:27:58PM +0900, Fujii Masao wrote:
> For the test, BASE_BACKUP needs to be canceled after it finishes
> do_pg_backup_start(), i.e., checkpointing, and before it calls
> do_pg_backup_stop(). So the timing to cancel that seems more severe
> than the test added in 0475a97f. I'm afraid that some tests can
> easily cancel the BASE_BACKUP while it's performing a checkpoint in
> do_pg_backup_start(). So for now I'm thinking to avoid such an
> unstable test.

Hmm.  In order to make sure that the checkpoint of the base backup is
completed, and assuming that the checkpoint is fast while the base
backup has a max rate, you could rely on a query that does a
poll_query_until() on pg_control_checkpoint(), no?  As long as you use
IPC::Run::start, pg_basebackup would be async so the polling query and
the cancellation can be done in parallel of it.  0475a97 did almost
that, except that it waits for the WAL sender to be started.
--
Michael

Commits

  1. Add more TAP tests with BASE_BACKUP and pg_backup_start/stop

  2. Fix assertion failure and segmentation fault in backup code.

  3. Prevent BASE_BACKUP in the middle of another backup in the same session.