Comment 21 for bug 1401133

There are 2 parts to this bug report:

1. Deadlock is triggered by the LOCK BINLOG FOR BACKUP statement
executed by XtraBackup
2. The XtraBackup connection is closed due to the above error while
holding a backup (TABLE) lock. Which results in a heap corruption and a
server crash, possibly some time later.

I believe #2 has been reported and fixed in PS 5.6.24-72.2 with
https://github.com/percona/percona-server/pull/26

Which means the latest PXC release 5.6.24-25.11 should not crash when
backup locks are used by XtraBackup if my
assumption is correct, but XtraBackup may still fail with an error due
to #1.

#1 (as in, a deadlock with LOCK BINLOG FOR BACKUP) looks like a
PXC-specific issue, but so far I’ve been unable to reproduce it
neither with PXC 5.6.22-25.8 nor with PXC 5.6.24-25.11. Here’s what I
tried:

1. sysbench OLTP_RW workload + concurrent LOCK * FOR BACKUP statements
in the same sequence as executed by XtraBackup on the same node
2. sysbench autocommit updates + same concurrent LOCK * FOR BACKUP
statements on the same
3. the above 2 case, but with LOCK * FOR BACKUP statements executed on
the same node where queries coming from sysbench are executed
4. all of the above cases with binary logging enabled.

At this point I’m out of ideas on how to reproduce the deadlock with
LOCK BINLOG FOR BACKUP issue.

If you can still reproduce either #1 or #2 with PXC 5.6.24-25.11 or a
later release, please provide your my.cnf _and_ at least a general
description of your workload (tables, queries, storage engines involved,
etc.)

Thank you.