**Reported in Launchpad by Ramesh Sivaraman last update 28-02-2015 14:55:32

mysqld: /mnt/workspace/percona-server-5.6-binaries-debug-yassl/label_exp/centos6-64/percona-server-5.6.21-70.0/sql/lock.cc:1217: void Global_backup_lo
ck::release_protection(THD*): Assertion `m_prot_lock != __null && thd->mdl_context.is_lock_owner(m_namespace, "", "", MDL_INTENTION_EXCLUSIVE)' failed
.
06:40:18 UTC - mysqld got signal 6 ;

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    • Testcase (Reproduced with debug build - Attached server start-up command)

DROP DATABASE test;CREATE DATABASE test;USE test;

SET SESSION AUTOCOMMIT=0;
SET @@global.master_info_repository="TABLE";
CREATE TABLE t1(c1 INT UNSIGNED);
FLUSH LOCAL TABLES t1 WITH READ LOCK;
CHANGE MASTER TO MASTER_HEARTBEAT_PERIOD=0.1;

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      • GDB info
        #0 0x00007f6d8990a771 in pthread_kill () from /lib64/libpthread.so.0
        #1 0x0000000000ab7e66 in my_write_core (sig=6) at /mnt/workspace/percona-server-5.6-binaries-debug-yassl/label_exp/centos6-64/percona-server-5.6.21-70.0/mysys/stacktrace.c:422
        #2 0x000000000072fcd3 in handle_fatal_signal (sig=6) at /mnt/workspace/percona-server-5.6-binaries-debug-yassl/label_exp/centos6-64/percona-server-5.6.21-70.0/sql/signal_handler.cc:236
        #3 <signal handler called>
        #4 0x00007f6d8850e5c9 in raise () from /lib64/libc.so.6
        #5 0x00007f6d8850fcd8 in abort () from /lib64/libc.so.6
        #6 0x00007f6d88507536 in __assert_fail_base () from /lib64/libc.so.6
        #7 0x00007f6d885075e2 in __assert_fail () from /lib64/libc.so.6
        #8 0x0000000000957dd0 in Global_backup_lock::release_protection (this=0x7f6ce8e3ba28, thd=0x7f6ce8e3a000) at /mnt/workspace/percona-server-5.6-binaries-debug-yassl/label_exp/centos6-64/percona-server-5.6.21-70.0/sql/lock.cc:1215
        #9 0x0000000000a66061 in global_init_info (mi=0x7f6ce8f9f000, ignore_if_no_info=false, thread_mask=3) at /mnt/workspace/percona-server-5.6-binaries-debug-yassl/label_exp/centos6-64/percona-server-5.6.21-70.0/sql/rpl_slave.cc:592
        #10 0x0000000000a7b94a in change_master (thd=0x7f6ce8e3a000, mi=0x7f6ce8f9f000) at /mnt/workspace/percona-server-5.6-binaries-debug-yassl/label_exp/centos6-64/percona-server-5.6.21-70.0/sql/rpl_slave.cc:8385
        #11 0x00000000007e3a41 in mysql_execute_command (thd=0x7f6ce8e3a000) at /mnt/workspace/percona-server-5.6-binaries-debug-yassl/label_exp/centos6-64/percona-server-5.6.21-70.0/sql/sql_parse.cc:3183
        #12 0x00000000007ed49f in mysql_parse (thd=0x7f6ce8e3a000, rawbuf=0x7f6ccac1f010 "CHANGE MASTER TO MASTER_HEARTBEAT_PERIOD=0.1", length=44, parser_state=0x7f6d89ec0df0) at /mnt/workspace/percona-server-5.6-binaries-debug-yassl/label_exp/centos6-64/percona-server-5.6.21-70.0/sql/sql_parse.cc:6777
        #13 0x00000000007df8be in dispatch_command (command=COM_QUERY, thd=0x7f6ce8e3a000, packet=0x7f6ce8a91001 "CHANGE MASTER TO MASTER_HEARTBEAT_PERIOD=0.1", packet_length=44) at /mnt/workspace/percona-server-5.6-binaries-debug-yassl/label_exp/centos6-64/percona-server-5.6.21-70.0/sql/sql_parse.cc:1432
        #14 0x00000000007de7dc in do_command (thd=0x7f6ce8e3a000) at /mnt/workspace/percona-server-5.6-binaries-debug-yassl/label_exp/centos6-64/percona-server-5.6.21-70.0/sql/sql_parse.cc:1049
        #15 0x00000000007a6785 in do_handle_one_connection (thd_arg=0x7f6ce8e3a000) at /mnt/workspace/percona-server-5.6-binaries-debug-yassl/label_exp/centos6-64/percona-server-5.6.21-70.0/sql/sql_connect.cc:1532
        #16 0x00000000007a628d in handle_one_connection (arg=0x7f6ce8e3a000) at /mnt/workspace/percona-server-5.6-binaries-debug-yassl/label_exp/centos6-64/percona-server-5.6.21-70.0/sql/sql_connect.cc:1443
        #17 0x0000000000dc648c in pfs_spawn_thread (arg=0x7f6d82f48c40) at /mnt/workspace/percona-server-5.6-binaries-debug-yassl/label_exp/centos6-64/percona-server-5.6.21-70.0/storage/perfschema/pfs.cc:1860
        #18 0x00007f6d89905df3 in start_thread () from /lib64/libpthread.so.0
        #19 0x00007f6d885cf01d in clone () from /lib64/libc.so.6
        (gdb) +set logging off