Horton

Re: Race condition in recovery?

Dilip Kumar <dilipbalaut@gmail.com>

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From: Dilip Kumar <dilipbalaut@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>, hlinnaka <hlinnaka@iki.fi>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-06-04T07:51:08Z
Lists: pgsql-hackers

Attachments

On Fri, Jun 4, 2021 at 2:03 AM Robert Haas <robertmhaas@gmail.com> wrote:
>
> On Thu, May 27, 2021 at 2:26 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> > Changed as suggested.
>
> I don't think the code as written here is going to work on Windows,
> because your code doesn't duplicate enable_restoring's call to
> perl2host or its backslash-escaping logic. It would really be better
> if we could use enable_restoring directly. Also, I discovered that the
> 'return' in cp_history_files should really say 'exit', because
> otherwise it generates a complaint every time it's run. It should also
> have 'use strict' and 'use warnings' at the top.

Ok

> Here's a version of your test case patch with the 1-line code fix
> added, the above issues addressed, and a bunch of cosmetic tweaks.
> Unfortunately, it doesn't pass for me consistently. I'm not sure if
> that's because I broke something with my changes, or because the test
> contains an underlying race condition which we need to address.
> Attached also are the log files from a failed run if you want to look
> at them. The key lines seem to be:

I could not reproduce this but I think I got the issue, I think I used
the wrong target LSN in wait_for_catchup, instead of checking the last
"insert LSN" of the standby I was waiting for last "replay LSN" of
standby which was wrong.  Changed as below in the attached patch.

diff --git a/src/test/recovery/t/025_stuck_on_old_timeline.pl
b/src/test/recovery/t/025_stuck_on_old_timeline.pl
index 09eb3eb..ee7d78d 100644
--- a/src/test/recovery/t/025_stuck_on_old_timeline.pl
+++ b/src/test/recovery/t/025_stuck_on_old_timeline.pl
@@ -78,7 +78,7 @@ $node_standby->safe_psql('postgres', "CREATE TABLE
tab_int AS SELECT 1 AS a");

 # Wait for the replication to catch up
 $node_standby->wait_for_catchup($node_cascade, 'replay',
-       $node_standby->lsn('replay'));
+       $node_standby->lsn('insert'));

 # Check that cascading standby has the new content
 my $result =

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com

Commits

  1. Further refinement of stuck_on_old_timeline recovery test

  2. Adjust new test case to set wal_keep_segments.

  3. Adjust new test case to set wal_keep_size.

  4. Fix corner case failure of new standby to follow new primary.

  5. Back-port a few PostgresNode.pm methods.

  6. Allow PostgresNode.pm's backup method to accept backup_options.

  7. Add end-to-end testing of pg_basebackup's tar-format output.

  8. Allow PostgresNode.pm tests to wait for catchup

  9. Delay reading timeline history file until it's fetched from master.