rpl_4threads_deadlock may crash due to concurrent dbug access

[Laurynas Biveinis]

rpl.rpl_4threads_deadlock 'stmt' w2 [ fail ]
...
mysqltest: In included file "./include/rpl_end.inc":
included from ./include/rpl_end.inc at line 77:
At line 77: query 'let $_tmp= query_get_value(SHOW SLAVE STATUS, Master_Host, 1)' failed: 2013: Lost connection to MySQL server during query
...
rogram terminated with signal 11, Segmentation fault.
#0 0x00007f4ea33d7e32 in pthread_kill () from /lib64/libpthread.so.0
#0 0x00007f4ea33d7e32 in pthread_kill () from /lib64/libpthread.so.0
#1 0x0000000000801489 in my_write_core (sig=11)
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/mysys/stacktrace.c:433
#2 0x00000000006c482d in handle_fatal_signal (sig=11)
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/sql/signal_handler.cc:250
#3 <signal handler called>
#4 0x00007f4ea1b94f34 in internal_fnmatch () from /lib64/libc.so.6
#5 0x00007f4ea1b98949 in fnmatch@@GLIBC_2.2.5 () from /lib64/libc.so.6
#6 0x0000000000a1f72a in InList (linkp=0x7265000000000000,
    cp=0xa44333 "enter")
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/dbug/dbug.c:1501
#7 0x0000000000a1f9e7 in _db_keyword_ (cs=0x2770990,
    keyword=0xa44333 "enter", strict=65538)
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/dbug/dbug.c:1718
#8 0x0000000000a203e1 in _db_doprnt_ (
    format=0xb054a4 "root: 0x%lx flags: %u")
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/dbug/dbug.c:1262
#9 0x00000000007f4c3e in free_root (root=0x283c578, MyFlags=0)
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/mysys/my_alloc.c:351
#10 0x0000000000584586 in THD::~THD (this=0x283aca0,
    __in_chrg=<value optimized out>)
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/sql/sql_class.cc:1590
#11 0x00000000005849e5 in THD::~THD (this=0x283aca0,
    __in_chrg=<value optimized out>)
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/sql/sql_class.cc:1612
#12 0x000000000051a1fc in delete_thd (thd=0x283aca0)
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/sql/mysqld.cc:2199
#13 0x000000000051e932 in unlink_thd (thd=0x283aca0)
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/sql/mysqld.cc:2229
#14 0x000000000051e989 in one_thread_per_connection_end (thd=0x283aca0,
    put_in_cache=true)
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/sql/mysqld.cc:2333
#15 0x000000000065bc28 in do_handle_one_connection (
    thd_arg=<value optimized out>)
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/sql/sql_connect.cc:1432
#16 0x000000000065bca9 in handle_one_connection (arg=0x283aca0)
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/sql/sql_connect.cc:1325
#17 0x000000000081566e in pfs_spawn_thread (arg=0x27e92c0)
    at /mnt/workspace/percona-server-5.5-param/BUILD_TYPE/debug/Host/centos5-64/storage/perfschema/pfs.cc:1015
#18 0x00007f4ea33d283d in start_thread () from /lib64/libpthread.so.0
#19 0x00007f4ea1bcafdd in clone () from /lib64/libc.so.6
...

SET GLOBAL debug=... is running in parallel with previous asynchronous disconnects, resulting in concurrent unprotected dbug data structure access.

[Laurynas Biveinis (laurynas-biveinis)]

    https://github.com/percona/percona-server/pull/720
    https://github.com/percona/percona-server/pull/721
    https://github.com/percona/percona-server/pull/722

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-2161