Sporadic debug_sync failures in Jenkins

[Alexey Kopytov]

I see a number of tests involving the debug_sync facility started to fail recently in Jenkins.

bug766305.sh and bug1291299.sh fail most frequently with the following symptoms:

------------
xtrabackup: DEBUG: Suspending at debug sync point 'data_copy_thread_func'. Resume with 'kill -SIGCONT 27079'.
Waited 1 seconds for /mnt/workspace/percona-xtrabackup-2.2-param/BUILD_TYPE/debug/Host/ubuntu-utopic-64bit/xtrabackuptarget/galera56/storage/innobase/xtrabackup/test/var/w3/var1/backup/xtrabackup_debug_sync to be created
2015-01-17 02:00:12: run.sh: ===> /mnt/workspace/percona-xtrabackup-2.2-param/BUILD_TYPE/debug/Host/ubuntu-utopic-64bit/xtrabackuptarget/galera56/storage/innobase/xtrabackup/test/server/bin/mysql --defaults-file=/mnt/workspace/percona-xtrabackup-2.2-param/BUILD_TYPE/debug/Host/ubuntu-utopic-64bit/xtrabackuptarget/galera56/storage/innobase/xtrabackup/test/var/w3/var1/my.cnf test
2015-01-17 02:00:12: run.sh: Resuming xtrabackup
>> log scanned up to (1634865)
2015-01-17 02:00:12: run.sh: ===> wait 27073
07:00:12 UTC - xtrabackup got signal 11 ;
This could be because you hit a bug or data is corrupted.
This error can also be caused by malfunctioning hardware.
We will try our best to scrape up some info that will hopefully help
diagnose the problem, but since we have already crashed,
something is definitely wrong and this may fail.

Thread pointer: 0x0
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
stack_bottom = 0 thread_stack 0x10000
/mnt/workspace/percona-xtrabackup-2.2-param/BUILD_TYPE/debug/Host/ubuntu-utopic-64bit/xtrabackuptarget/galera56/storage/innobase/xtrabackup/test/../src/xtrabackup(my_print_stacktrace+0x47) [0xc196d4]
/mnt/workspace/percona-xtrabackup-2.2-param/BUILD_TYPE/debug/Host/ubuntu-utopic-64bit/xtrabackuptarget/galera56/storage/innobase/xtrabackup/test/../src/xtrabackup(handle_fatal_signal+0x2ce) [0xb890d7]
/lib/x86_64-linux-gnu/libpthread.so.0(+0xfc90) [0x7f6fc29fec90]
/lib/x86_64-linux-gnu/libpthread.so.0(pthread_cond_timedwait+0x129) [0x7f6fc29fb5f9]
/mnt/workspace/percona-xtrabackup-2.2-param/BUILD_TYPE/debug/Host/ubuntu-utopic-64bit/xtrabackuptarget/galera56/storage/innobase/xtrabackup/test/../src/xtrabackup() [0x88096c]
/mnt/workspace/percona-xtrabackup-2.2-param/BUILD_TYPE/debug/Host/ubuntu-utopic-64bit/xtrabackuptarget/galera56/storage/innobase/xtrabackup/test/../src/xtrabackup(os_event_wait_time_low(os_event*, unsigned long, long)+0x194) [0x88119a]
/mnt/workspace/percona-xtrabackup-2.2-param/BUILD_TYPE/debug/Host/ubuntu-utopic-64bit/xtrabackuptarget/galera56/storage/innobase/xtrabackup/test/../src/xtrabackup() [0x6068d3]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x80a5) [0x7f6fc29f70a5]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d) [0x7f6fc121a88d]

Please report a bug at https://bugs.launchpad.net/percona-xtrabackup
2015-01-17 02:00:12: run.sh: ===> xtrabackup failed with exit code 1
2015-01-17 02:00:12: run.sh: ===> wait failed with exit code 1
------------

For some reasons, the failures only occur in 2.2, but not in 2.3.

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PXB-1314