Assertion `!pool->busy' failed in pool_mark_busy(rpl_parallel_thread_pool*) on concurrent FTWRL

sql/rpl_parallel.cc:380: void pool_mark_busy(rpl_parallel_thread_pool*): Assertion `!pool->busy' failed.

150614 18:40:00 [ERROR] mysqld got signal 6 ;

#6  0x00007f518a4e7311 in *__GI___assert_fail (assertion=0xf72b51 "!pool->busy", file=<optimized out>, line=380, function=0xf740a0 "void pool_mark_busy(rpl_parallel_thread_pool*)") at assert.c:81

#7  0x00000000007f80cb in pool_mark_busy (pool=0x189d8e0) at sql/rpl_parallel.cc:380

#8  0x00000000007f8356 in rpl_pause_for_ftwrl (thd=0x7f51853eb070) at sql/rpl_parallel.cc:449

#9  0x0000000000682933 in mysql_execute_command (thd=0x7f51853eb070) at sql/sql_parse.cc:4282

#10 0x00000000009afc04 in sp_instr_stmt::exec_core (this=0x7f51820bef88, thd=0x7f51853eb070, nextp=0x7f518c614978) at sql/sp_head.cc:3204

#11 0x00000000009af355 in sp_lex_keeper::reset_lex_and_exec_core (this=0x7f51820befc8, thd=0x7f51853eb070, nextp=0x7f518c614978, open_tables=false, instr=0x7f51820bef88) at sql/sp_head.cc:2971

#12 0x00000000009af90e in sp_instr_stmt::execute (this=0x7f51820bef88, thd=0x7f51853eb070, nextp=0x7f518c614978) at sql/sp_head.cc:3120

#13 0x00000000009ab726 in sp_head::execute (this=0x7f51820bd088, thd=0x7f51853eb070, merge_da_on_success=true) at sql/sp_head.cc:1371

#14 0x00000000009ad3d2 in sp_head::execute_procedure (this=0x7f51820bd088, thd=0x7f51853eb070, args=0x7f51853ef670) at sql/sp_head.cc:2159

#15 0x0000000000683d61 in mysql_execute_command (thd=0x7f51853eb070) at sql/sql_parse.cc:4714

#16 0x00000000006884e9 in mysql_parse (thd=0x7f51853eb070, rawbuf=0x7f5182022088 "CALL pr()", length=9, parser_state=0x7f518c615600) at sql/sql_parse.cc:6542

#17 0x000000000067ae7b in dispatch_command (command=COM_QUERY, thd=0x7f51853eb070, packet=0x7f51853f1071 "CALL pr()", packet_length=9) at sql/sql_parse.cc:1308

#18 0x000000000067a161 in do_command (thd=0x7f51853eb070) at sql/sql_parse.cc:999

#19 0x000000000079827b in do_handle_one_connection (thd_arg=0x7f51853eb070) at sql/sql_connect.cc:1375

#20 0x0000000000797fce in handle_one_connection (arg=0x7f51853eb070) at sql/sql_connect.cc:1289

#21 0x0000000000cd8337 in pfs_spawn_thread (arg=0x7f5184584af0) at storage/perfschema/pfs.cc:1860

#22 0x00007f518c2e1b50 in start_thread (arg=<optimized out>) at pthread_create.c:304

#23 0x00007f518a59795d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112

--source include/have_log_bin.inc

--source include/have_binlog_format_row.inc

CREATE TABLE t1 (pk INT AUTO_INCREMENT PRIMARY KEY, i INT);

CREATE TABLE t2 (pk INT AUTO_INCREMENT PRIMARY KEY, i INT);

CREATE PROCEDURE pr() FLUSH TABLES WITH READ LOCK;

--connect (con1,localhost,root,,)

--let $con1 = `SELECT CONNECTION_ID()`

--send CALL pr()

--connect (con2,localhost,root,,)

--let $con2 = `SELECT CONNECTION_ID()`

--send CALL pr()

--connection default

--sleep 120

eval KILL $con1;

eval KILL $con2;

--echo # Nothing happened, finishing.

DROP TABLE t1, t2;

DROP PROCEDURE pr;