(gdb) +thread apply all bt

Thread 41 (LWP 30185):
+bt
#0  0x00007fdacaa8ec0d in fsync () from /lib64/libpthread.so.0
#1  0x00000000008e59ad in os_file_fsync (file=128, metadata=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:2113
#2  0x00000000008e7524 in os_file_flush_func (file=128, metadata=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:2216
#3  pfs_os_file_flush_func (src_line=2036, src_file=0xa7b368 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c", metadata=1, file=128) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/include/os0file.ic:385
#4  os_file_set_size (name=0x7fda2c0041f8 "./query129983/#sql-74ca_56.ibd", file=128, size=<optimized out>, size_high=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:2036
#5  0x00000000008a0a31 in fil_create_new_single_table_tablespace (space_id=5399, tablename=0x7fda2c247f70 "query129983/#sql-74ca_56", is_temp=0, flags=0, size=4) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:2838
#6  0x000000000087d974 in dict_build_table_def_step (thr=0x7fda2c034060, node=0x7fda2c20f2e8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/dict/dict0crea.c:294
#7  0x000000000087e01c in dict_create_table_step (thr=0x7fda2c034060) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/dict/dict0crea.c:1089
#8  0x0000000000900305 in que_thr_step (thr=0x7fda2c034060) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/que/que0que.c:1267
#9  que_run_threads_low (thr=0x7fda2c034060) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/que/que0que.c:1319
#10 que_run_threads (thr=0x7fda2c034060) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/que/que0que.c:1356
#11 0x00000000007ffa60 in row_create_table_for_mysql (table=0x7fda2c012a98, trx=0x7fda2c260f28) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1999
#12 0x00000000007e5f23 in create_table_def (flags=1, path_of_temp_table=<optimized out>, table_name=0x7fdab2461f00 "query129983/#sql-74ca_56", form=0x7fdab24623d0, trx=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:7551
#13 ha_innobase::create (this=<optimized out>, name=<optimized out>, form=0x7fdab24623d0, create_info=0x7fdab2466610) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8160
#14 0x000000000068db93 in ha_create_table (thd=0x278a2b0, path=<optimized out>, db=0x7fda2c037050 "query129983", table_name=0x7fdab2465f60 "#sql-74ca_56", create_info=<optimized out>, update_create_info=240) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/handler.cc:4018
#15 0x0000000000614d3b in rea_create_table (thd=0x278a2b0, path=0x7fdab2464180 "./query129983/#sql-74ca_56", db=0x7fda2c037050 "query129983", table_name=0x7fdab2465f60 "#sql-74ca_56", create_info=0x7fdab2466610, create_fields=..., keys=58, key_info=0x7fda2c1b8178, file=0x7fda2c1b6530) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/unireg.cc:528
#16 0x00000000005e8ff5 in mysql_create_table_no_lock (thd=0x278a2b0, db=0x7fda2c037050 "query129983", table_name=0x7fdab2465f60 "#sql-74ca_56", create_info=0x7fdab2466610, alter_info=0x7fdab24666f0, internal_tmp_table=true, select_field_count=0, is_trans=0x0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:4323
#17 0x00000000005eda80 in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x7fda2c037068 "t6", create_info=0x7fdab2466610, table_list=0x7fda2c037001, alter_info=0x7fdab24666f0, order_num=0, order=0x0, ignore=false) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:6597
#18 0x000000000078ed7f in Alter_table_statement::execute (this=<optimized out>, thd=0x278a2b0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#19 0x000000000058ae8c in mysql_execute_command (thd=0x278a2b0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#20 0x000000000058e643 in mysql_parse (thd=0x278a2b0, rawbuf=<optimized out>, length=41467520, parser_state=0x7fdab2467bb0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#21 0x000000000058fcbd in dispatch_command (command=COM_QUERY, thd=0x278a2b0, packet=0x7fda2c036f70 "ALTER TABLE query129983 . `t6` DROP COLUMN `c63`", packet_length=2990963864) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#22 0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#23 0x000000000062a691 in handle_one_connection (arg=0x278a2b0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#24 0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#25 0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 40 (LWP 29915):
+bt
#0  0x00007fdacaa8ec0d in fsync () from /lib64/libpthread.so.0
#1  0x00000000008e59ad in os_file_fsync (file=149, metadata=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:2113
#2  0x00000000008e649e in os_file_flush_func (file=<optimized out>, metadata=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:2216
#3  0x000000000089bff0 in pfs_os_file_flush_func (src_line=5699, file=149, metadata=<optimized out>, src_file=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/include/os0file.ic:385
#4  fil_flush (space_id=<optimized out>, metadata=1) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5699
#5  0x000000000089c3a5 in fil_flush_file_spaces (purpose=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5782
#6  0x000000000086ce5c in buf_flush_sync_datafiles () at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c:702
#7  buf_flush_buffered_writes () at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c:725
#8  0x000000000086eb95 in buf_flush_batch (buf_pool=0x22bc548, flush_type=<optimized out>, min_n=200, lsn_limit=18446744073709551615) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c:1864
#9  0x000000000086f23d in buf_flush_list (min_n=200, lsn_limit=18446744073709551615) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c:2073
#10 0x00000000008186e8 in srv_master_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0srv.c:3838
#11 0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#12 0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 39 (LWP 30186):
+bt
#0  0x00007fdacaa8b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00000000008eb101 in os_cond_wait (mutex=0x0, cond=0x264be40) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=0x264be00, reset_sig_count=18796) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000081ec1f in sync_array_wait_event (arr=0x1e24650, index=2) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000081f6b7 in rw_lock_x_lock_func (lock=0x1090a40 <dict_operation_lock>, pass=0, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0rw.c:700
#5  0x00000000007fced6 in pfs_rw_lock_x_lock_func (line=8156, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", lock=<optimized out>, pass=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:689
#6  row_mysql_lock_data_dictionary_func (trx=0x2906498, file=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1851
#7  0x00000000007e5b06 in ha_innobase::create (this=<optimized out>, name=<optimized out>, form=0x7fdab25253d0, create_info=0x7fdab2529610) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8156
#8  0x000000000068db93 in ha_create_table (thd=0x27a8160, path=<optimized out>, db=0x27ab360 "query129978", table_name=0x7fdab2528f60 "#sql-74ca_57", create_info=<optimized out>, update_create_info=240) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/handler.cc:4018
#9  0x0000000000614d3b in rea_create_table (thd=0x27a8160, path=0x7fdab2527180 "./query129978/#sql-74ca_57", db=0x27ab360 "query129978", table_name=0x7fdab2528f60 "#sql-74ca_57", create_info=0x7fdab2529610, create_fields=..., keys=58, key_info=0x296ff68, file=0x296e320) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/unireg.cc:528
#10 0x00000000005e8ff5 in mysql_create_table_no_lock (thd=0x27a8160, db=0x27ab360 "query129978", table_name=0x7fdab2528f60 "#sql-74ca_57", create_info=0x7fdab2529610, alter_info=0x7fdab25296f0, internal_tmp_table=true, select_field_count=0, is_trans=0x0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:4323
#11 0x00000000005eda80 in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x27ab378 "t6", create_info=0x7fdab2529610, table_list=0x27ab301, alter_info=0x7fdab25296f0, order_num=0, order=0x0, ignore=false) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:6597
#12 0x000000000078ed7f in Alter_table_statement::execute (this=<optimized out>, thd=0x27a8160) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#13 0x000000000058ae8c in mysql_execute_command (thd=0x27a8160) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#14 0x000000000058e643 in mysql_parse (thd=0x27a8160, rawbuf=<optimized out>, length=41590064, parser_state=0x7fdab252abb0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#15 0x000000000058fcbd in dispatch_command (command=COM_QUERY, thd=0x27a8160, packet=0x27ab280 "ALTER TABLE query129978 . `t6` DROP COLUMN `c63`", packet_length=2991762584) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#16 0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#17 0x000000000062a691 in handle_one_connection (arg=0x27a8160) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#18 0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#19 0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 38 (LWP 30176):
+bt
#0  0x00007fdacaa8b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00000000008eb101 in os_cond_wait (mutex=0x0, cond=0x264be40) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=0x264be00, reset_sig_count=18796) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000081ec1f in sync_array_wait_event (arr=0x1e24650, index=9) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000081f6b7 in rw_lock_x_lock_func (lock=0x1090a40 <dict_operation_lock>, pass=0, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0rw.c:700
#5  0x00000000007fced6 in pfs_rw_lock_x_lock_func (line=8156, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", lock=<optimized out>, pass=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:689
#6  row_mysql_lock_data_dictionary_func (trx=0x29d0b88, file=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1851
#7  0x00000000007e5b06 in ha_innobase::create (this=<optimized out>, name=<optimized out>, form=0x7fdab25663d0, create_info=0x7fdab256a610) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8156
#8  0x000000000068db93 in ha_create_table (thd=0x278df30, path=<optimized out>, db=0x26ee0d0 "query130041", table_name=0x7fdab2569f60 "#sql-74ca_51", create_info=<optimized out>, update_create_info=240) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/handler.cc:4018
#9  0x0000000000614d3b in rea_create_table (thd=0x278df30, path=0x7fdab2568180 "./query130041/#sql-74ca_51", db=0x26ee0d0 "query130041", table_name=0x7fdab2569f60 "#sql-74ca_51", create_info=0x7fdab256a610, create_fields=..., keys=58, key_info=0x2adce68, file=0x2adb220) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/unireg.cc:528
#10 0x00000000005e8ff5 in mysql_create_table_no_lock (thd=0x278df30, db=0x26ee0d0 "query130041", table_name=0x7fdab2569f60 "#sql-74ca_51", create_info=0x7fdab256a610, alter_info=0x7fdab256a6f0, internal_tmp_table=true, select_field_count=0, is_trans=0x0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:4323
#11 0x00000000005eda80 in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x26ee0e8 "t6", create_info=0x7fdab256a610, table_list=0x26ee101, alter_info=0x7fdab256a6f0, order_num=0, order=0x0, ignore=false) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:6597
#12 0x000000000078ed7f in Alter_table_statement::execute (this=<optimized out>, thd=0x278df30) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#13 0x000000000058ae8c in mysql_execute_command (thd=0x278df30) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#14 0x000000000058e643 in mysql_parse (thd=0x278df30, rawbuf=<optimized out>, length=41483008, parser_state=0x7fdab256bbb0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#15 0x000000000058fcbd in dispatch_command (command=COM_QUERY, thd=0x278df30, packet=0x26edff0 "ALTER TABLE query130041 . `t6` DROP COLUMN `c51`", packet_length=2992028824) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#16 0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#17 0x000000000062a691 in handle_one_connection (arg=0x278df30) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#18 0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#19 0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 37 (LWP 30181):
+bt
#0  0x00007fdacaa8b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00000000008eb101 in os_cond_wait (mutex=0x0, cond=0x264be40) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=0x264be00, reset_sig_count=18796) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000081ec1f in sync_array_wait_event (arr=0x1e24650, index=4) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000081f6b7 in rw_lock_x_lock_func (lock=0x1090a40 <dict_operation_lock>, pass=0, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0rw.c:700
#5  0x00000000007fced6 in pfs_rw_lock_x_lock_func (line=8156, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", lock=<optimized out>, pass=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:689
#6  row_mysql_lock_data_dictionary_func (trx=0x29cd388, file=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1851
#7  0x00000000007e5b06 in ha_innobase::create (this=<optimized out>, name=<optimized out>, form=0x7fdab24a33d0, create_info=0x7fdab24a7610) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8156
#8  0x000000000068db93 in ha_create_table (thd=0x27871a0, path=<optimized out>, db=0x26f2ba0 "query130011", table_name=0x7fdab24a6f60 "#sql-74ca_54", create_info=<optimized out>, update_create_info=240) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/handler.cc:4018
#9  0x0000000000614d3b in rea_create_table (thd=0x27871a0, path=0x7fdab24a5180 "./query130011/#sql-74ca_54", db=0x26f2ba0 "query130011", table_name=0x7fdab24a6f60 "#sql-74ca_54", create_info=0x7fdab24a7610, create_fields=..., keys=58, key_info=0x2913778, file=0x2911b30) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/unireg.cc:528
#10 0x00000000005e8ff5 in mysql_create_table_no_lock (thd=0x27871a0, db=0x26f2ba0 "query130011", table_name=0x7fdab24a6f60 "#sql-74ca_54", create_info=0x7fdab24a7610, alter_info=0x7fdab24a76f0, internal_tmp_table=true, select_field_count=0, is_trans=0x0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:4323
#11 0x00000000005eda80 in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x26f2bb8 "t6", create_info=0x7fdab24a7610, table_list=0x26f2b01, alter_info=0x7fdab24a76f0, order_num=0, order=0x0, ignore=false) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:6597
#12 0x000000000078ed7f in Alter_table_statement::execute (this=<optimized out>, thd=0x27871a0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#13 0x000000000058ae8c in mysql_execute_command (thd=0x27871a0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#14 0x000000000058e643 in mysql_parse (thd=0x27871a0, rawbuf=<optimized out>, length=41454960, parser_state=0x7fdab24a8bb0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#15 0x000000000058fcbd in dispatch_command (command=COM_QUERY, thd=0x27871a0, packet=0x26f2ac0 "ALTER TABLE query130011 . `t6` DROP COLUMN `c63`", packet_length=2991230104) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#16 0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#17 0x000000000062a691 in handle_one_connection (arg=0x27871a0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#18 0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#19 0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 36 (LWP 30031):
+bt
#0  0x00007fdacaa8e54d in read () from /lib64/libpthread.so.0
#1  0x000000000051ebc4 in my_real_read (net=0x274e758, complen=0x7fdac80a0dc8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#2  0x000000000051ef3c in my_net_read (net=0x274e758) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#3  0x0000000000590048 in do_command (thd=0x274e510) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#4  0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#5  0x000000000062a691 in handle_one_connection (arg=0x274e510) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#6  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#7  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 35 (LWP 30189):
+bt
#0  0x00007fdacaa8b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00000000008eb101 in os_cond_wait (mutex=0x0, cond=0x264be40) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=0x264be00, reset_sig_count=18796) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000081ec1f in sync_array_wait_event (arr=0x1e24650, index=3) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000081f6b7 in rw_lock_x_lock_func (lock=0x1090a40 <dict_operation_lock>, pass=0, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0rw.c:700
#5  0x00000000007fced6 in pfs_rw_lock_x_lock_func (line=8156, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", lock=<optimized out>, pass=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:689
#6  row_mysql_lock_data_dictionary_func (trx=0x29bb918, file=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1851
#7  0x00000000007e5b06 in ha_innobase::create (this=<optimized out>, name=<optimized out>, form=0x7fdab23e03d0, create_info=0x7fdab23e4610) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8156
#8  0x000000000068db93 in ha_create_table (thd=0x27bd3b0, path=<optimized out>, db=0x26b6130 "query130027", table_name=0x7fdab23e3f60 "#sql-74ca_59", create_info=<optimized out>, update_create_info=240) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/handler.cc:4018
#9  0x0000000000614d3b in rea_create_table (thd=0x27bd3b0, path=0x7fdab23e2180 "./query130027/#sql-74ca_59", db=0x26b6130 "query130027", table_name=0x7fdab23e3f60 "#sql-74ca_59", create_info=0x7fdab23e4610, create_fields=..., keys=58, key_info=0x2a88a48, file=0x2a86e00) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/unireg.cc:528
#10 0x00000000005e8ff5 in mysql_create_table_no_lock (thd=0x27bd3b0, db=0x26b6130 "query130027", table_name=0x7fdab23e3f60 "#sql-74ca_59", create_info=0x7fdab23e4610, alter_info=0x7fdab23e46f0, internal_tmp_table=true, select_field_count=0, is_trans=0x0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:4323
#11 0x00000000005eda80 in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x26b6148 "t6", create_info=0x7fdab23e4610, table_list=0x26b6101, alter_info=0x7fdab23e46f0, order_num=0, order=0x0, ignore=false) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:6597
#12 0x000000000078ed7f in Alter_table_statement::execute (this=<optimized out>, thd=0x27bd3b0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#13 0x000000000058ae8c in mysql_execute_command (thd=0x27bd3b0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#14 0x000000000058e643 in mysql_parse (thd=0x27bd3b0, rawbuf=<optimized out>, length=41676672, parser_state=0x7fdab23e5bb0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#15 0x000000000058fcbd in dispatch_command (command=COM_QUERY, thd=0x27bd3b0, packet=0x26b6050 "ALTER TABLE query130027 . `t6` DROP COLUMN `c63`", packet_length=2990431384) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#16 0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#17 0x000000000062a691 in handle_one_connection (arg=0x27bd3b0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#18 0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#19 0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 34 (LWP 29906):
+bt
#0  0x00007fdaca87f614 in ?? () from /lib64/libaio.so.1
#1  0x00000000008e9683 in os_aio_linux_collect (seg_size=256, segment=<optimized out>, array=0x2299ac0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=6, message1=0x7fdab8a79e78, message2=0x7fdab8a79e70, type=0x7fdab8a79e68, space_id=0x7fdab8a79e60) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x00000000008a77ba in fil_aio_wait (segment=6) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x000000000081a630 in io_handler_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#6  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 33 (LWP 30028):
+bt
#0  0x00007fdacaa8e54d in read () from /lib64/libpthread.so.0
#1  0x000000000051ebc4 in my_real_read (net=0x2747638, complen=0x7fdac80e1dc8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#2  0x000000000051ef3c in my_net_read (net=0x2747638) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#3  0x0000000000590048 in do_command (thd=0x27473f0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#4  0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#5  0x000000000062a691 in handle_one_connection (arg=0x27473f0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#6  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#7  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 32 (LWP 29977):
+bt
#0  0x00007fdacaa8e54d in read () from /lib64/libpthread.so.0
#1  0x000000000051ebc4 in my_real_read (net=0x2713338, complen=0x7fdac878cdc8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#2  0x000000000051ef3c in my_net_read (net=0x2713338) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#3  0x0000000000590048 in do_command (thd=0x27130f0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#4  0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#5  0x000000000062a691 in handle_one_connection (arg=0x27130f0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#6  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#7  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 31 (LWP 29903):
+bt
#0  0x00007fdaca87f614 in ?? () from /lib64/libaio.so.1
#1  0x00000000008e9683 in os_aio_linux_collect (seg_size=256, segment=<optimized out>, array=0x2291800) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=3, message1=0x7fdaba87ce78, message2=0x7fdaba87ce70, type=0x7fdaba87ce68, space_id=0x7fdaba87ce60) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x00000000008a77ba in fil_aio_wait (segment=3) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x000000000081a630 in io_handler_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#6  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 30 (LWP 29905):
+bt
#0  0x00007fdaca87f614 in ?? () from /lib64/libaio.so.1
#1  0x00000000008e9683 in os_aio_linux_collect (seg_size=256, segment=<optimized out>, array=0x2291800) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=5, message1=0x7fdab947ae78, message2=0x7fdab947ae70, type=0x7fdab947ae68, space_id=0x7fdab947ae60) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x00000000008a77ba in fil_aio_wait (segment=5) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x000000000081a630 in io_handler_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#6  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 29 (LWP 29904):
+bt
#0  0x00007fdaca87f614 in ?? () from /lib64/libaio.so.1
#1  0x00000000008e9683 in os_aio_linux_collect (seg_size=256, segment=<optimized out>, array=0x2291800) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=4, message1=0x7fdab9e7be78, message2=0x7fdab9e7be70, type=0x7fdab9e7be68, space_id=0x7fdab9e7be60) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x00000000008a77ba in fil_aio_wait (segment=4) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x000000000081a630 in io_handler_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#6  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 28 (LWP 29902):
+bt
#0  0x00007fdaca87f614 in ?? () from /lib64/libaio.so.1
#1  0x00000000008e9683 in os_aio_linux_collect (seg_size=256, segment=<optimized out>, array=0x2291800) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=2, message1=0x7fdabb27de78, message2=0x7fdabb27de70, type=0x7fdabb27de68, space_id=0x7fdabb27de60) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x00000000008a77ba in fil_aio_wait (segment=2) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x000000000081a630 in io_handler_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#6  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 27 (LWP 29900):
+bt
#0  0x00007fdaca87f614 in ?? () from /lib64/libaio.so.1
#1  0x00000000008e9683 in os_aio_linux_collect (seg_size=256, segment=<optimized out>, array=0x2275280) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=0, message1=0x7fdac99c1e78, message2=0x7fdac99c1e70, type=0x7fdac99c1e68, space_id=0x7fdac99c1e60) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x00000000008a77ba in fil_aio_wait (segment=0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x000000000081a630 in io_handler_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#6  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 26 (LWP 29901):
+bt
#0  0x00007fdaca87f614 in ?? () from /lib64/libaio.so.1
#1  0x00000000008e9683 in os_aio_linux_collect (seg_size=256, segment=<optimized out>, array=0x2283540) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=1, message1=0x7fdabbc7ee78, message2=0x7fdabbc7ee70, type=0x7fdabbc7ee68, space_id=0x7fdabbc7ee60) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x00000000008a77ba in fil_aio_wait (segment=1) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x000000000081a630 in io_handler_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#6  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 25 (LWP 30012):
+bt
#0  0x00007fdacaa8e54d in read () from /lib64/libpthread.so.0
#1  0x000000000051ebc4 in my_real_read (net=0x267e718, complen=0x7fdac84c1dc8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#2  0x000000000051ef3c in my_net_read (net=0x267e718) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#3  0x0000000000590048 in do_command (thd=0x267e4d0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#4  0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#5  0x000000000062a691 in handle_one_connection (arg=0x267e4d0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#6  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#7  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 24 (LWP 29898):
+bt
#0  0x00007fdac9d03a63 in poll () from /lib64/libc.so.6
#1  0x0000000000516d04 in handle_connections_sockets () at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/mysqld.cc:5383
#2  0x000000000051ce78 in mysqld_main (argc=55, argv=0x1df9218) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/mysqld.cc:4822
#3  0x00007fdac9c43cdd in __libc_start_main () from /lib64/libc.so.6
#4  0x0000000000512049 in _start ()

Thread 23 (LWP 30010):
+bt
#0  0x00007fdacaa8e54d in read () from /lib64/libpthread.so.0
#1  0x000000000051ebc4 in my_real_read (net=0x26aa988, complen=0x7fdac8543dc8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#2  0x000000000051ef3c in my_net_read (net=0x26aa988) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#3  0x0000000000590048 in do_command (thd=0x26aa740) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#4  0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#5  0x000000000062a691 in handle_one_connection (arg=0x26aa740) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#6  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#7  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 22 (LWP 30342):
+bt
#0  0x00007fdacaa8b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00000000008eb101 in os_cond_wait (mutex=0x0, cond=0x264be40) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=0x264be00, reset_sig_count=18796) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000081ec1f in sync_array_wait_event (arr=0x1e24650, index=1) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000081f6b7 in rw_lock_x_lock_func (lock=0x1090a40 <dict_operation_lock>, pass=0, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0rw.c:700
#5  0x00000000007fced6 in pfs_rw_lock_x_lock_func (line=8156, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", lock=<optimized out>, pass=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:689
#6  row_mysql_lock_data_dictionary_func (trx=0x7fda2806aa28, file=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1851
#7  0x00000000007e5b06 in ha_innobase::create (this=<optimized out>, name=<optimized out>, form=0x7fdab25a73d0, create_info=0x7fdab25ab610) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8156
#8  0x000000000068db93 in ha_create_table (thd=0x29a0cf0, path=<optimized out>, db=0x7fda2802dd30 "query130003", table_name=0x7fdab25aaf60 "#sql-74ca_90", create_info=<optimized out>, update_create_info=240) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/handler.cc:4018
#9  0x0000000000614d3b in rea_create_table (thd=0x29a0cf0, path=0x7fdab25a9180 "./query130003/#sql-74ca_90", db=0x7fda2802dd30 "query130003", table_name=0x7fdab25aaf60 "#sql-74ca_90", create_info=0x7fdab25ab610, create_fields=..., keys=8, key_info=0x7fda28090fe8, file=0x7fda28086780) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/unireg.cc:528
#10 0x00000000005e8ff5 in mysql_create_table_no_lock (thd=0x29a0cf0, db=0x7fda2802dd30 "query130003", table_name=0x7fdab25aaf60 "#sql-74ca_90", create_info=0x7fdab25ab610, alter_info=0x7fdab25ab6f0, internal_tmp_table=true, select_field_count=0, is_trans=0x0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:4323
#11 0x00000000005eda80 in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x7fda2802dd48 "t5", create_info=0x7fdab25ab610, table_list=0x7fda2802dd01, alter_info=0x7fdab25ab6f0, order_num=0, order=0x0, ignore=false) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:6597
#12 0x000000000078ed7f in Alter_table_statement::execute (this=<optimized out>, thd=0x29a0cf0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#13 0x000000000058ae8c in mysql_execute_command (thd=0x29a0cf0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#14 0x000000000058e643 in mysql_parse (thd=0x29a0cf0, rawbuf=<optimized out>, length=43657408, parser_state=0x7fdab25acbb0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#15 0x000000000058fcbd in dispatch_command (command=COM_QUERY, thd=0x29a0cf0, packet=0x7fda2802dc50 "ALTER TABLE query130003 . `t5` DROP COLUMN `c88`", packet_length=2992295064) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#16 0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#17 0x000000000062a691 in handle_one_connection (arg=0x29a0cf0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#18 0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#19 0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 21 (LWP 30294):
+bt
#0  0x00007fdacaa8b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00000000008eb101 in os_cond_wait (mutex=0x0, cond=0x264be40) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=0x264be00, reset_sig_count=18796) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000081ec1f in sync_array_wait_event (arr=0x1e24650, index=5) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000081f6b7 in rw_lock_x_lock_func (lock=0x1090a40 <dict_operation_lock>, pass=0, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0rw.c:700
#5  0x00000000007fced6 in pfs_rw_lock_x_lock_func (line=8156, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", lock=<optimized out>, pass=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:689
#6  row_mysql_lock_data_dictionary_func (trx=0x7fda70057988, file=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1851
#7  0x00000000007e5b06 in ha_innobase::create (this=<optimized out>, name=<optimized out>, form=0x7fdac86423d0, create_info=0x7fdac8646610) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8156
#8  0x000000000068db93 in ha_create_table (thd=0x27e03f0, path=<optimized out>, db=0x7fda7000c3b8 "query130030", table_name=0x7fdac8645f60 "#sql-74ca_7e", create_info=<optimized out>, update_create_info=240) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/handler.cc:4018
#9  0x0000000000614d3b in rea_create_table (thd=0x27e03f0, path=0x7fdac8644180 "./query130030/#sql-74ca_7e", db=0x7fda7000c3b8 "query130030", table_name=0x7fdac8645f60 "#sql-74ca_7e", create_info=0x7fdac8646610, create_fields=..., keys=7, key_info=0x7fda70015998, file=0x7fda7003ab40) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/unireg.cc:528
#10 0x00000000005e8ff5 in mysql_create_table_no_lock (thd=0x27e03f0, db=0x7fda7000c3b8 "query130030", table_name=0x7fdac8645f60 "#sql-74ca_7e", create_info=0x7fdac8646610, alter_info=0x7fdac86466f0, internal_tmp_table=true, select_field_count=0, is_trans=0x0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:4323
#11 0x00000000005eda80 in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x7fda7000c3d0 "t5", create_info=0x7fdac8646610, table_list=0x7fda7000c401, alter_info=0x7fdac86466f0, order_num=0, order=0x0, ignore=false) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:6597
#12 0x000000000078ed7f in Alter_table_statement::execute (this=<optimized out>, thd=0x27e03f0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#13 0x000000000058ae8c in mysql_execute_command (thd=0x27e03f0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#14 0x000000000058e643 in mysql_parse (thd=0x27e03f0, rawbuf=<optimized out>, length=41820096, parser_state=0x7fdac8647bb0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#15 0x000000000058fcbd in dispatch_command (command=COM_QUERY, thd=0x27e03f0, packet=0x7fda7000c2e0 "ALTER TABLE query130030 . `t5` DROP COLUMN `c4`", packet_length=3362028696) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#16 0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#17 0x000000000062a691 in handle_one_connection (arg=0x27e03f0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#18 0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#19 0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 20 (LWP 30005):
+bt
#0  0x00007fdacaa8e54d in read () from /lib64/libpthread.so.0
#1  0x000000000051ebc4 in my_real_read (net=0x26b3178, complen=0x7fdac8584dc8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#2  0x000000000051ef3c in my_net_read (net=0x26b3178) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#3  0x0000000000590048 in do_command (thd=0x26b2f30) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#4  0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#5  0x000000000062a691 in handle_one_connection (arg=0x26b2f30) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#6  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#7  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 19 (LWP 30344):
+bt
#0  0x00007fdacaa8b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00000000008eb101 in os_cond_wait (mutex=0x0, cond=0x264be40) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=0x264be00, reset_sig_count=18796) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000081ec1f in sync_array_wait_event (arr=0x1e24650, index=0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000081f6b7 in rw_lock_x_lock_func (lock=0x1090a40 <dict_operation_lock>, pass=0, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0rw.c:700
#5  0x00000000007fced6 in pfs_rw_lock_x_lock_func (line=8156, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", lock=<optimized out>, pass=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:689
#6  row_mysql_lock_data_dictionary_func (trx=0x7fda6c07c8e8, file=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1851
#7  0x00000000007e5b06 in ha_innobase::create (this=<optimized out>, name=<optimized out>, form=0x7fdac81e03d0, create_info=0x7fdac81e4610) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8156
#8  0x000000000068db93 in ha_create_table (thd=0x281b940, path=<optimized out>, db=0x7fda6c00bd88 "query130009", table_name=0x7fdac81e3f60 "#sql-74ca_91", create_info=<optimized out>, update_create_info=240) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/handler.cc:4018
#9  0x0000000000614d3b in rea_create_table (thd=0x281b940, path=0x7fdac81e2180 "./query130009/#sql-74ca_91", db=0x7fda6c00bd88 "query130009", table_name=0x7fdac81e3f60 "#sql-74ca_91", create_info=0x7fdac81e4610, create_fields=..., keys=8, key_info=0x7fda6c0373e0, file=0x7fda6c022e50) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/unireg.cc:528
#10 0x00000000005e8ff5 in mysql_create_table_no_lock (thd=0x281b940, db=0x7fda6c00bd88 "query130009", table_name=0x7fdac81e3f60 "#sql-74ca_91", create_info=0x7fdac81e4610, alter_info=0x7fdac81e46f0, internal_tmp_table=true, select_field_count=0, is_trans=0x0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:4323
#11 0x00000000005eda80 in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x7fda6c00bda0 "t5", create_info=0x7fdac81e4610, table_list=0x7fda6c00bd01, alter_info=0x7fdac81e46f0, order_num=0, order=0x0, ignore=false) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:6597
#12 0x000000000078ed7f in Alter_table_statement::execute (this=<optimized out>, thd=0x281b940) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#13 0x000000000058ae8c in mysql_execute_command (thd=0x281b940) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#14 0x000000000058e643 in mysql_parse (thd=0x281b940, rawbuf=<optimized out>, length=42063120, parser_state=0x7fdac81e5bb0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#15 0x000000000058fcbd in dispatch_command (command=COM_QUERY, thd=0x281b940, packet=0x7fda6c00bcb0 "ALTER TABLE query130009 . `t5` DROP COLUMN `c0`", packet_length=3357432984) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#16 0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#17 0x000000000062a691 in handle_one_connection (arg=0x281b940) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#18 0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#19 0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 18 (LWP 30188):
+bt
#0  0x00007fdacaa8b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00000000008eb101 in os_cond_wait (mutex=0x0, cond=0x264be40) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=0x264be00, reset_sig_count=18796) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000081ec1f in sync_array_wait_event (arr=0x1e24650, index=7) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000081f6b7 in rw_lock_x_lock_func (lock=0x1090a40 <dict_operation_lock>, pass=0, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0rw.c:700
#5  0x00000000007fced6 in pfs_rw_lock_x_lock_func (line=8156, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", lock=<optimized out>, pass=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:689
#6  row_mysql_lock_data_dictionary_func (trx=0x7fda2c158d08, file=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1851
#7  0x00000000007e5b06 in ha_innobase::create (this=<optimized out>, name=<optimized out>, form=0x7fdab24213d0, create_info=0x7fdab2425610) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8156
#8  0x000000000068db93 in ha_create_table (thd=0x2799060, path=<optimized out>, db=0x7fda2c03d080 "query129974", table_name=0x7fdab2424f60 "#sql-74ca_58", create_info=<optimized out>, update_create_info=240) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/handler.cc:4018
#9  0x0000000000614d3b in rea_create_table (thd=0x2799060, path=0x7fdab2423180 "./query129974/#sql-74ca_58", db=0x7fda2c03d080 "query129974", table_name=0x7fdab2424f60 "#sql-74ca_58", create_info=0x7fdab2425610, create_fields=..., keys=58, key_info=0x7fda2c1e58f8, file=0x7fda2c1e3cb0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/unireg.cc:528
#10 0x00000000005e8ff5 in mysql_create_table_no_lock (thd=0x2799060, db=0x7fda2c03d080 "query129974", table_name=0x7fdab2424f60 "#sql-74ca_58", create_info=0x7fdab2425610, alter_info=0x7fdab24256f0, internal_tmp_table=true, select_field_count=0, is_trans=0x0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:4323
#11 0x00000000005eda80 in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x7fda2c03d098 "t6", create_info=0x7fdab2425610, table_list=0x7fda2c03d001, alter_info=0x7fdab24256f0, order_num=0, order=0x0, ignore=false) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:6597
#12 0x000000000078ed7f in Alter_table_statement::execute (this=<optimized out>, thd=0x2799060) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#13 0x000000000058ae8c in mysql_execute_command (thd=0x2799060) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#14 0x000000000058e643 in mysql_parse (thd=0x2799060, rawbuf=<optimized out>, length=41528368, parser_state=0x7fdab2426bb0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#15 0x000000000058fcbd in dispatch_command (command=COM_QUERY, thd=0x2799060, packet=0x7fda2c03cfa0 "ALTER TABLE query129974 . `t6` DROP COLUMN `c63`", packet_length=2990697624) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#16 0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#17 0x000000000062a691 in handle_one_connection (arg=0x2799060) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#18 0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#19 0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 17 (LWP 29984):
+bt
#0  0x00007fdacaa8e54d in read () from /lib64/libpthread.so.0
#1  0x000000000051ebc4 in my_real_read (net=0x2729c28, complen=0x7fdac86c9dc8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#2  0x000000000051ef3c in my_net_read (net=0x2729c28) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#3  0x0000000000590048 in do_command (thd=0x27299e0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#4  0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#5  0x000000000062a691 in handle_one_connection (arg=0x27299e0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#6  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#7  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 16 (LWP 30021):
+bt
#0  0x00007fdacaa8e54d in read () from /lib64/libpthread.so.0
#1  0x000000000051ebc4 in my_real_read (net=0x26cf998, complen=0x7fdac81a4dc8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#2  0x000000000051ef3c in my_net_read (net=0x26cf998) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#3  0x0000000000590048 in do_command (thd=0x26cf750) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#4  0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#5  0x000000000062a691 in handle_one_connection (arg=0x26cf750) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#6  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#7  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 15 (LWP 30300):
+bt
#0  0x00007fdacaa8b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00000000008eb101 in os_cond_wait (mutex=0x0, cond=0x264be40) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=0x264be00, reset_sig_count=18796) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000081ec1f in sync_array_wait_event (arr=0x1e24650, index=6) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000081f6b7 in rw_lock_x_lock_func (lock=0x1090a40 <dict_operation_lock>, pass=0, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0rw.c:700
#5  0x00000000007fced6 in pfs_rw_lock_x_lock_func (line=8156, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", lock=<optimized out>, pass=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:689
#6  row_mysql_lock_data_dictionary_func (trx=0x7fda38036cc8, file=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1851
#7  0x00000000007e5b06 in ha_innobase::create (this=<optimized out>, name=<optimized out>, form=0x7fdac805a3d0, create_info=0x7fdac805e610) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8156
#8  0x000000000068db93 in ha_create_table (thd=0x2738a80, path=<optimized out>, db=0x7fda3801b920 "query130020", table_name=0x7fdac805df60 "#sql-74ca_81", create_info=<optimized out>, update_create_info=240) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/handler.cc:4018
#9  0x0000000000614d3b in rea_create_table (thd=0x2738a80, path=0x7fdac805c180 "./query130020/#sql-74ca_81", db=0x7fda3801b920 "query130020", table_name=0x7fdac805df60 "#sql-74ca_81", create_info=0x7fdac805e610, create_fields=..., keys=8, key_info=0x7fda38042df8, file=0x7fda38054a80) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/unireg.cc:528
#10 0x00000000005e8ff5 in mysql_create_table_no_lock (thd=0x2738a80, db=0x7fda3801b920 "query130020", table_name=0x7fdac805df60 "#sql-74ca_81", create_info=0x7fdac805e610, alter_info=0x7fdac805e6f0, internal_tmp_table=true, select_field_count=0, is_trans=0x0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:4323
#11 0x00000000005eda80 in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x7fda3801b938 "t5", create_info=0x7fdac805e610, table_list=0x7fda3801b901, alter_info=0x7fdac805e6f0, order_num=0, order=0x0, ignore=false) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:6597
#12 0x000000000078ed7f in Alter_table_statement::execute (this=<optimized out>, thd=0x2738a80) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#13 0x000000000058ae8c in mysql_execute_command (thd=0x2738a80) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#14 0x000000000058e643 in mysql_parse (thd=0x2738a80, rawbuf=<optimized out>, length=41133648, parser_state=0x7fdac805fbb0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#15 0x000000000058fcbd in dispatch_command (command=COM_QUERY, thd=0x2738a80, packet=0x7fda3801b840 "ALTER TABLE query130020 . `t5` DROP COLUMN `c88`", packet_length=3355835544) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#16 0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#17 0x000000000062a691 in handle_one_connection (arg=0x2738a80) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#18 0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#19 0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 14 (LWP 29979):
+bt
#0  0x00007fdacaa8e54d in read () from /lib64/libpthread.so.0
#1  0x000000000051ebc4 in my_real_read (net=0x271ab88, complen=0x7fdac874bdc8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#2  0x000000000051ef3c in my_net_read (net=0x271ab88) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#3  0x0000000000590048 in do_command (thd=0x271a940) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#4  0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#5  0x000000000062a691 in handle_one_connection (arg=0x271a940) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#6  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#7  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 13 (LWP 29918):
+bt
#0  0x00007fdacaa8e54d in read () from /lib64/libpthread.so.0
#1  0x000000000051ebc4 in my_real_read (net=0x2674988, complen=0x7fdac884fdc8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#2  0x000000000051ef3c in my_net_read (net=0x2674988) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#3  0x0000000000590048 in do_command (thd=0x2674740) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#4  0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#5  0x000000000062a691 in handle_one_connection (arg=0x2674740) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#6  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#7  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 12 (LWP 30195):
+bt
#0  0x00007fdacaa8b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00000000008eb101 in os_cond_wait (mutex=0x0, cond=0x264be40) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=0x264be00, reset_sig_count=18796) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000081ec1f in sync_array_wait_event (arr=0x1e24650, index=8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000081f6b7 in rw_lock_x_lock_func (lock=0x1090a40 <dict_operation_lock>, pass=0, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0rw.c:700
#5  0x00000000007fced6 in pfs_rw_lock_x_lock_func (line=8156, file_name=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", lock=<optimized out>, pass=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:689
#6  row_mysql_lock_data_dictionary_func (trx=0x7fda2c22bf78, file=0xa55638 "/ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8156) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1851
#7  0x00000000007e5b06 in ha_innobase::create (this=<optimized out>, name=<optimized out>, form=0x7fdab239f3d0, create_info=0x7fdab23a3610) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8156
#8  0x000000000068db93 in ha_create_table (thd=0x2812350, path=<optimized out>, db=0x7fda2c041cd0 "query129976", table_name=0x7fdab23a2f60 "#sql-74ca_5c", create_info=<optimized out>, update_create_info=240) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/handler.cc:4018
#9  0x0000000000614d3b in rea_create_table (thd=0x2812350, path=0x7fdab23a1180 "./query129976/#sql-74ca_5c", db=0x7fda2c041cd0 "query129976", table_name=0x7fdab23a2f60 "#sql-74ca_5c", create_info=0x7fdab23a3610, create_fields=..., keys=56, key_info=0x7fda2c1ea7e0, file=0x7fda2c0d7fd0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/unireg.cc:528
#10 0x00000000005e8ff5 in mysql_create_table_no_lock (thd=0x2812350, db=0x7fda2c041cd0 "query129976", table_name=0x7fdab23a2f60 "#sql-74ca_5c", create_info=0x7fdab23a3610, alter_info=0x7fdab23a36f0, internal_tmp_table=true, select_field_count=0, is_trans=0x0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:4323
#11 0x00000000005eda80 in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x7fda2c041ce8 "t6", create_info=0x7fdab23a3610, table_list=0x7fda2c041d01, alter_info=0x7fdab23a36f0, order_num=0, order=0x0, ignore=false) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:6597
#12 0x000000000078ed7f in Alter_table_statement::execute (this=<optimized out>, thd=0x2812350) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#13 0x000000000058ae8c in mysql_execute_command (thd=0x2812350) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#14 0x000000000058e643 in mysql_parse (thd=0x2812350, rawbuf=<optimized out>, length=42024736, parser_state=0x7fdab23a4bb0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#15 0x000000000058fcbd in dispatch_command (command=COM_QUERY, thd=0x2812350, packet=0x7fda2c041bf0 "ALTER TABLE query129976 . `t6` DROP COLUMN `c28`", packet_length=2990165144) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#16 0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#17 0x000000000062a691 in handle_one_connection (arg=0x2812350) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#18 0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#19 0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 11 (LWP 29975):
+bt
#0  0x00007fdacaa8e54d in read () from /lib64/libpthread.so.0
#1  0x000000000051ebc4 in my_real_read (net=0x270bae8, complen=0x7fdac87cddc8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#2  0x000000000051ef3c in my_net_read (net=0x270bae8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#3  0x0000000000590048 in do_command (thd=0x270b8a0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#4  0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#5  0x000000000062a691 in handle_one_connection (arg=0x270b8a0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#6  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#7  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 10 (LWP 29916):
+bt
#0  0x00007fdac9d05d03 in select () from /lib64/libc.so.6
#1  0x00000000008ebe0f in os_thread_sleep (tm=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0thread.c:259
#2  0x000000000081a3bf in srv_purge_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0srv.c:4047
#3  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#4  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 9 (LWP 30043):
+bt
#0  0x00007fdacaa8e54d in read () from /lib64/libpthread.so.0
#1  0x000000000051ebc4 in my_real_read (net=0x276abd8, complen=0x7fdab25eddc8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#2  0x000000000051ef3c in my_net_read (net=0x276abd8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#3  0x0000000000590048 in do_command (thd=0x276a990) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#4  0x000000000062a557 in do_handle_one_connection (thd_arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#5  0x000000000062a691 in handle_one_connection (arg=0x276a990) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#6  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#7  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 8 (LWP 29912):
+bt
#0  0x00007fdacaa8b7bb in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00000000008eafb3 in os_cond_wait_timed (abstime=0x7fdab5874d90, mutex=0x20f9560, cond=0x20f95a0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:171
#2  os_event_wait_time_low (event=0x20f9560, time_in_usec=<optimized out>, reset_sig_count=1) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:716
#3  0x00000000008198a5 in srv_error_monitor_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0srv.c:2907
#4  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#5  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 7 (LWP 29917):
+bt
#0  0x00007fdacaa8f2a5 in sigwait () from /lib64/libpthread.so.0
#1  0x0000000000515bbb in signal_hand (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/mysqld.cc:2748
#2  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#3  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 6 (LWP 29911):
+bt
#0  0x00007fdacaa8b7bb in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00000000008eafb3 in os_cond_wait_timed (abstime=0x7fdab6275db0, mutex=0x20f95f0, cond=0x20f9630) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:171
#2  os_event_wait_time_low (event=0x20f95f0, time_in_usec=<optimized out>, reset_sig_count=1) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:716
#3  0x0000000000819c88 in srv_lock_timeout_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0srv.c:2694
#4  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#5  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 5 (LWP 29914):
+bt
#0  0x00007fdac9d05d03 in select () from /lib64/libc.so.6
#1  0x00000000008ebe0f in os_thread_sleep (tm=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0thread.c:259
#2  0x000000000081362a in srv_LRU_dump_restore_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0srv.c:2953
#3  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#4  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 4 (LWP 29908):
+bt
#0  0x00007fdaca87f614 in ?? () from /lib64/libaio.so.1
#1  0x00000000008e9683 in os_aio_linux_collect (seg_size=256, segment=<optimized out>, array=0x2299ac0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=8, message1=0x7fdab7677e78, message2=0x7fdab7677e70, type=0x7fdab7677e68, space_id=0x7fdab7677e60) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x00000000008a77ba in fil_aio_wait (segment=8) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x000000000081a630 in io_handler_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#6  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 3 (LWP 29913):
+bt
#0  0x00007fdacaa8b7bb in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00000000008eafb3 in os_cond_wait_timed (abstime=0x7fdab4e73e10, mutex=0x20f9680, cond=0x20f96c0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:171
#2  os_event_wait_time_low (event=0x20f9680, time_in_usec=<optimized out>, reset_sig_count=1) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:716
#3  0x00000000008170bb in srv_monitor_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0srv.c:2544
#4  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#5  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 2 (LWP 29909):
+bt
#0  0x00007fdaca87f614 in ?? () from /lib64/libaio.so.1
#1  0x00000000008e9683 in os_aio_linux_collect (seg_size=256, segment=<optimized out>, array=0x2299ac0) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=9, message1=0x7fdab6c76e78, message2=0x7fdab6c76e70, type=0x7fdab6c76e68, space_id=0x7fdab6c76e60) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x00000000008a77ba in fil_aio_wait (segment=9) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x000000000081a630 in io_handler_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#6  0x00007fdac9d0d11d in clone () from /lib64/libc.so.6

Thread 1 (LWP 29907):
+bt
#0  0x00007fdacaa8c69c in pthread_kill () from /lib64/libpthread.so.0
#1  0x000000000068836e in handle_fatal_signal (sig=6) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/sql/signal_handler.cc:249
#2  <signal handler called>
#3  0x00007fdac9c578a5 in raise () from /lib64/libc.so.6
#4  0x00007fdac9c59085 in abort () from /lib64/libc.so.6
#5  0x000000000086b974 in buf_flush_remove (bpage=0x7fdabbf07f00) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c:544
#6  0x000000000086b9b7 in buf_flush_write_complete (bpage=0x7fdabbf07f00) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c:659
#7  0x0000000000866011 in buf_page_io_complete (bpage=0x7fdabbf07f00) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0buf.c:4186
#8  0x00000000008a792b in fil_aio_wait (segment=7) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5611
#9  0x000000000081a630 in io_handler_thread (arg=<optimized out>) at /ssd/QA-16724-5.5-2/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#10 0x00007fdacaa87851 in start_thread () from /lib64/libpthread.so.0
#11 0x00007fdac9d0d11d in clone () from /lib64/libc.so.6
(gdb) +quit