(gdb) +thread apply all bt

Thread 26 (LWP 2255):
+bt
#0  0x0000003da180b902 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x000000000099a17d in os_cond_wait_timed (abstime=0x7f2ab8a9cda0, mutex=0x32d9480, cond=0x32d94b8) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:171
#2  os_event_wait_time_low (event=0x32d9480, time_in_usec=time_in_usec@entry=1000000, reset_sig_count=1) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:716
#3  0x0000000000874b1e in srv_error_monitor_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0srv.c:2911
#4  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#5  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 25 (LWP 2606):
+bt
#0  0x0000003da180e0ad in read () from /lib64/libpthread.so.0
#1  0x0000000000a5f176 in vio_read (vio=0x383e080, buf=0x383e270 "\001", size=4) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/vio/viosocket.c:56
#2  0x0000000000524070 in my_real_read (net=net@entry=0x383aa30, complen=complen@entry=0x7f2ac8177d88) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#3  0x0000000000524b91 in my_net_read (net=0x383aa30) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#4  0x00000000005a3e59 in do_command (thd=0x383a800) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#5  0x000000000064e11c in do_handle_one_connection (thd_arg=thd_arg@entry=0x383a800) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#6  0x000000000064e212 in handle_one_connection (arg=0x383a800) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#7  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#8  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 24 (LWP 2248):
+bt
#0  0x0000003fa1400614 in ?? () from /lib64/libaio.so.1
#1  0x0000000000997787 in os_aio_linux_collect (seg_size=256, segment=1, array=0x34524e0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=global_seg@entry=7, message1=message1@entry=0x7f2abbb5ee68, message2=message2@entry=0x7f2abbb5ee60, type=type@entry=0x7f2abbb5ee58, space_id=space_id@entry=0x7f2abbb5ee50) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x0000000000939627 in fil_aio_wait (segment=segment@entry=7) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x0000000000878bda in io_handler_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#6  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 23 (LWP 2402):
+bt
#0  0x0000003da180e0ad in read () from /lib64/libpthread.so.0
#1  0x0000000000a5f176 in vio_read (vio=0x3830580, buf=0x38366d0 "\a", size=4) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/vio/viosocket.c:56
#2  0x0000000000524070 in my_real_read (net=net@entry=0x37ab900, complen=complen@entry=0x7f2ac81b8d88) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#3  0x0000000000524b91 in my_net_read (net=0x37ab900) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#4  0x00000000005a3e59 in do_command (thd=0x37ab6d0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#5  0x000000000064e11c in do_handle_one_connection (thd_arg=thd_arg@entry=0x37ab6d0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#6  0x000000000064e212 in handle_one_connection (arg=0x37ab6d0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#7  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#8  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 22 (LWP 2625):
+bt
#0  0x0000003da180e0ad in read () from /lib64/libpthread.so.0
#1  0x0000000000a5f176 in vio_read (vio=0x37a7eb0, buf=0x3872770 "\001", size=4) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/vio/viosocket.c:56
#2  0x0000000000524070 in my_real_read (net=net@entry=0x386f870, complen=complen@entry=0x7f2aba35bd88) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#3  0x0000000000524b91 in my_net_read (net=0x386f870) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#4  0x00000000005a3e59 in do_command (thd=0x386f640) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#5  0x000000000064e11c in do_handle_one_connection (thd_arg=thd_arg@entry=0x386f640) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#6  0x000000000064e212 in handle_one_connection (arg=0x386f640) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#7  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#8  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 21 (LWP 2259):
+bt
#0  0x0000003da180b595 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x000000000099a275 in os_cond_wait (mutex=0x377cb20, cond=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=event@entry=0x377cb20, reset_sig_count=90908) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000087cb0e in sync_array_wait_event (arr=0x3027430, index=0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000087d741 in rw_lock_s_lock_spin (lock=0x11c8a60 <dict_operation_lock>, pass=pass@entry=0, file_name=file_name@entry=0xb9f650 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0purge.c", line=line@entry=680) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0rw.c:453
#5  0x000000000084446d in rw_lock_s_lock_func (line=680, file_name=0xb9f650 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0purge.c", pass=0, lock=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:419
#6  pfs_rw_lock_s_lock_func (line=680, file_name=0xb9f650 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0purge.c", pass=0, lock=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:779
#7  row_mysql_freeze_data_dictionary_func (trx=trx@entry=0x379f798, file=file@entry=0xb9f650 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0purge.c", line=line@entry=680) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1814
#8  0x00000000009d5a37 in row_purge_parse_undo_rec (thr=0x37a0260, updated_extern=0x7f2ab6a98c28, node=0x37a0418) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0purge.c:680
#9  row_purge (thr=0x37a0260, node=0x37a0418) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0purge.c:758
#10 row_purge_step (thr=thr@entry=0x37a0260) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0purge.c:805
#11 0x00000000009be35f in que_thr_step (thr=0x37a0260) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/que/que0que.c:1259
#12 que_run_threads_low (thr=0x37a0260) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/que/que0que.c:1319
#13 que_run_threads (thr=thr@entry=0x37a0260) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/que/que0que.c:1356
#14 0x0000000000887312 in trx_purge (limit=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/trx/trx0purge.c:1195
#15 0x0000000000878593 in srv_purge_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0srv.c:4041
#16 0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#17 0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 20 (LWP 2383):
+bt
#0  0x0000003da180ed70 in sigwait () from /lib64/libpthread.so.0
#1  0x000000000051b7cc in signal_hand (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/mysqld.cc:2748
#2  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#3  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 19 (LWP 2254):
+bt
#0  0x0000003da180b902 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x000000000099a17d in os_cond_wait_timed (abstime=0x7f2ab929ddc0, mutex=0x32d9500, cond=0x32d9538) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:171
#2  os_event_wait_time_low (event=0x32d9500, time_in_usec=time_in_usec@entry=1000000, reset_sig_count=1) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:716
#3  0x0000000000873f25 in srv_lock_timeout_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0srv.c:2698
#4  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#5  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 18 (LWP 2610):
+bt
#0  0x0000003da180e0ad in read () from /lib64/libpthread.so.0
#1  0x0000000000a5f176 in vio_read (vio=0x384d160, buf=0x384d350 "\001", size=4) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/vio/viosocket.c:56
#2  0x0000000000524070 in my_real_read (net=net@entry=0x3849e40, complen=complen@entry=0x7f2ac8136d88) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:834
#3  0x0000000000524b91 in my_net_read (net=0x3849e40) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/net_serv.cc:1033
#4  0x00000000005a3e59 in do_command (thd=0x3849c10) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:734
#5  0x000000000064e11c in do_handle_one_connection (thd_arg=thd_arg@entry=0x3849c10) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#6  0x000000000064e212 in handle_one_connection (arg=0x3849c10) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#7  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#8  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 17 (LWP 2257):
+bt
#0  0x0000003da14ea9f3 in select () from /lib64/libc.so.6
#1  0x000000000099a98c in os_thread_sleep (tm=tm@entry=5000000) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0thread.c:259
#2  0x0000000000874b7e in srv_LRU_dump_restore_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0srv.c:2957
#3  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#4  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 16 (LWP 2250):
+bt
#0  0x0000003fa1400614 in ?? () from /lib64/libaio.so.1
#1  0x0000000000997787 in os_aio_linux_collect (seg_size=256, segment=3, array=0x34524e0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=global_seg@entry=9, message1=message1@entry=0x7f2abab5ce68, message2=message2@entry=0x7f2abab5ce60, type=type@entry=0x7f2abab5ce58, space_id=space_id@entry=0x7f2abab5ce50) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x0000000000939627 in fil_aio_wait (segment=segment@entry=9) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x0000000000878bda in io_handler_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#6  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 15 (LWP 2256):
+bt
#0  0x0000003da180b902 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x000000000099a17d in os_cond_wait_timed (abstime=0x7f2ab829be10, mutex=0x32d9580, cond=0x32d95b8) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:171
#2  os_event_wait_time_low (event=0x32d9580, time_in_usec=time_in_usec@entry=5000000, reset_sig_count=1) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:716
#3  0x0000000000873c1c in srv_monitor_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0srv.c:2548
#4  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#5  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 14 (LWP 24819):
+bt
#0  0x0000003da180b595 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x000000000099a275 in os_cond_wait (mutex=0x377cb20, cond=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=event@entry=0x377cb20, reset_sig_count=90908) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000087cb0e in sync_array_wait_event (arr=0x3027430, index=1) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000087de3d in rw_lock_x_lock_func (lock=0x11c8a60 <dict_operation_lock>, pass=pass@entry=0, file_name=file_name@entry=0xb62988 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=line@entry=8584) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0rw.c:700
#5  0x000000000084468b in pfs_rw_lock_x_lock_func (line=8584, file_name=0xb62988 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", pass=0, lock=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:689
#6  row_mysql_lock_data_dictionary_func (trx=0x7f29fc001cd8, file=0xb62988 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8584) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1851
#7  0x000000000081b692 in innobase_rename_table (lock_and_commit=1, to=0x7f2ab5fc9480 "./query12609/t1", from=0x7f2ab5fc9270 "./query12609/#sql-8bf_5f5", trx=0x7f29fc001cd8) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8584
#8  ha_innobase::rename_table (this=<optimized out>, from=<optimized out>, to=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8649
#9  0x00000000006b999d in handler::ha_rename_table (this=0x7f29fc0929d0, from=0x7f2ab5fc9270 "./query12609/#sql-8bf_5f5", to=0x7f2ab5fc9480 "./query12609/t1") at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/handler.cc:3645
#10 0x0000000000605b93 in mysql_rename_table (base=base@entry=0x30679b0, old_db=old_db@entry=0x7f29fc003bb8 "query12609", old_name=old_name@entry=0x7f2ab5fc9ce0 "#sql-8bf_5f5", new_db=new_db@entry=0x7f29fc003bb8 "query12609", new_name=new_name@entry=0x7f29fc003bd0 "t1", flags=flags@entry=1) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:4548
#11 0x000000000060afa8 in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x7f29fc003bd0 "t1", create_info=0x7f2ab5fcb230, table_list=0x7f29fc003bb8, alter_info=0x7f2ab5fcb100, order_num=0, order=0x0, ignore=false) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:6960
#12 0x00000000007bd089 in Alter_table_statement::execute (this=<optimized out>, thd=0x38423a0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#13 0x00000000005a0b95 in mysql_execute_command (thd=thd@entry=0x38423a0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#14 0x00000000005a1f2d in mysql_parse (thd=thd@entry=0x38423a0, rawbuf=<optimized out>, length=47, parser_state=parser_state@entry=0x7f2ab5fcc760) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#15 0x00000000005a2a08 in dispatch_command (command=command@entry=COM_QUERY, thd=thd@entry=0x38423a0, packet=packet@entry=0x3845801 "ALTER TABLE query12609 . `t1` DROP COLUMN `c82`", packet_length=packet_length@entry=47) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#16 0x00000000005a3fc3 in do_command (thd=0x38423a0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:788
#17 0x000000000064e11c in do_handle_one_connection (thd_arg=thd_arg@entry=0x38423a0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#18 0x000000000064e212 in handle_one_connection (arg=0x38423a0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#19 0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#20 0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 13 (LWP 2249):
+bt
#0  0x0000003da180b595 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x000000000099a275 in os_cond_wait (mutex=0x3775ce0, cond=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=event@entry=0x3775ce0, reset_sig_count=6219) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000087cb0e in sync_array_wait_event (arr=0x3027430, index=2) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000087e415 in mutex_spin_wait (mutex=mutex@entry=0x3475518, file_name=file_name@entry=0xb824e8 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c", line=line@entry=524) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0sync.c:653
#5  0x00000000008ebe73 in mutex_enter_func (line=524, file_name=0xb824e8 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c", mutex=0x3475518) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0sync.ic:222
#6  pfs_mutex_enter_func (line=524, file_name=0xb824e8 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c", mutex=0x3475518) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0sync.ic:251
#7  buf_flush_remove (bpage=0x7f2abbdffa30) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c:524
#8  0x00000000008ec791 in buf_flush_write_complete (bpage=bpage@entry=0x7f2abbdffa30) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c:659
#9  0x00000000008e3a7a in buf_page_io_complete (bpage=0x7f2abbdffa30) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0buf.c:4186
#10 0x00000000009397e6 in fil_aio_wait (segment=segment@entry=8) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5611
#11 0x0000000000878bda in io_handler_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#12 0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#13 0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 12 (LWP 2242):
+bt
#0  0x0000003fa1400614 in ?? () from /lib64/libaio.so.1
#1  0x0000000000997787 in os_aio_linux_collect (seg_size=256, segment=0, array=0x343bfe0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=global_seg@entry=1, message1=message1@entry=0x7f2acb1ffe68, message2=message2@entry=0x7f2acb1ffe60, type=type@entry=0x7f2acb1ffe58, space_id=space_id@entry=0x7f2acb1ffe50) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x0000000000939627 in fil_aio_wait (segment=segment@entry=1) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x0000000000878bda in io_handler_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#6  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 11 (LWP 2246):
+bt
#0  0x0000003fa1400614 in ?? () from /lib64/libaio.so.1
#1  0x0000000000997787 in os_aio_linux_collect (seg_size=256, segment=3, array=0x344a260) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=global_seg@entry=5, message1=message1@entry=0x7f2ac91fbe68, message2=message2@entry=0x7f2ac91fbe60, type=type@entry=0x7f2ac91fbe58, space_id=space_id@entry=0x7f2ac91fbe50) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x0000000000939627 in fil_aio_wait (segment=segment@entry=5) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x0000000000878bda in io_handler_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#6  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 10 (LWP 24786):
+bt
#0  0x0000003da180b595 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x000000000099a275 in os_cond_wait (mutex=0x377cb20, cond=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=event@entry=0x377cb20, reset_sig_count=90908) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000087cb0e in sync_array_wait_event (arr=0x3027430, index=4) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000087de3d in rw_lock_x_lock_func (lock=0x11c8a60 <dict_operation_lock>, pass=pass@entry=0, file_name=file_name@entry=0xb62988 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=line@entry=8157) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0rw.c:700
#5  0x000000000084468b in pfs_rw_lock_x_lock_func (line=8157, file_name=0xb62988 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", pass=0, lock=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0rw.ic:689
#6  row_mysql_lock_data_dictionary_func (trx=0x7f2a50037268, file=0xb62988 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc", line=8157) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:1851
#7  0x0000000000823a7b in ha_innobase::create (this=<optimized out>, name=<optimized out>, form=0x7f2aba14eff0, create_info=0x7f2aba152230) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8157
#8  0x00000000006b9d6f in handler::ha_create (this=0x7f2a500520b0, name=0x7f2aba14fc80 "./query02605/#sql-8bf_5f0", form=form@entry=0x7f2aba14eff0, info=info@entry=0x7f2aba152230) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/handler.cc:3690
#9  0x00000000006ba6e8 in ha_create_table (thd=0x3867dd0, path=<optimized out>, db=0x7f2a5002b2d8 "query02605", table_name=0x7f2aba150ce0 "#sql-8bf_5f0", create_info=0x7f2aba152230, update_create_info=false) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/handler.cc:4018
#10 0x00000000006335b4 in rea_create_table (thd=0x3867dd0, path=0x7f2aba14fc80 "./query02605/#sql-8bf_5f0", db=0x7f2a5002b2d8 "query02605", table_name=0x7f2aba150ce0 "#sql-8bf_5f0", create_info=0x7f2aba152230, create_fields=..., keys=26, key_info=0x7f2a50058000, file=0x7f2a5006e2a0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/unireg.cc:531
#11 0x00000000006054cc in mysql_create_table_no_lock (thd=thd@entry=0x3867dd0, db=db@entry=0x7f2a5002b2d8 "query02605", table_name=table_name@entry=0x7f2aba150ce0 "#sql-8bf_5f0", create_info=create_info@entry=0x7f2aba152230, alter_info=alter_info@entry=0x7f2aba152170, internal_tmp_table=false, internal_tmp_table@entry=true, select_field_count=select_field_count@entry=0, is_trans=is_trans@entry=0x0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:4325
#12 0x00000000006098af in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x7f2a5002b2f0 "t1", create_info=0x7f2aba152230, table_list=0x7f2a5002b328, alter_info=0x7f2aba152170, order_num=0, order=0x0, ignore=false) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:6597
#13 0x00000000007bd089 in Alter_table_statement::execute (this=<optimized out>, thd=0x3867dd0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#14 0x00000000005a0b95 in mysql_execute_command (thd=thd@entry=0x3867dd0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#15 0x00000000005a1f2d in mysql_parse (thd=thd@entry=0x3867dd0, rawbuf=<optimized out>, length=47, parser_state=parser_state@entry=0x7f2aba153760) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#16 0x00000000005a2a08 in dispatch_command (command=command@entry=COM_QUERY, thd=thd@entry=0x3867dd0, packet=packet@entry=0x386b231 "ALTER TABLE query02605 . `t1` DROP COLUMN `c84`", packet_length=packet_length@entry=47) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#17 0x00000000005a3fc3 in do_command (thd=0x3867dd0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:788
#18 0x000000000064e11c in do_handle_one_connection (thd_arg=thd_arg@entry=0x3867dd0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#19 0x000000000064e212 in handle_one_connection (arg=0x3867dd0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#20 0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#21 0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 9 (LWP 2247):
+bt
#0  0x0000003da180b595 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x000000000099a275 in os_cond_wait (mutex=0x34757c0, cond=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=event@entry=0x34757c0, reset_sig_count=2487) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x000000000087cb0e in sync_array_wait_event (arr=0x3027430, index=3) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0arr.c:458
#4  0x000000000087e415 in mutex_spin_wait (mutex=mutex@entry=0x3474ef8, file_name=file_name@entry=0xb7fe48 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0buf.c", line=line@entry=4147) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/sync/sync0sync.c:653
#5  0x00000000008dc262 in mutex_enter_func (mutex=0x3474ef8, file_name=0xb7fe48 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0buf.c", line=4147) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0sync.ic:222
#6  0x00000000008dc30f in pfs_mutex_enter_func (mutex=0x3474ef8, file_name=0xb7fe48 "/ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0buf.c", line=4147) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/include/sync0sync.ic:251
#7  0x00000000008e3c40 in buf_page_io_complete (bpage=0x7f2abbc43340) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0buf.c:4147
#8  0x00000000009397e6 in fil_aio_wait (segment=segment@entry=6) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5611
#9  0x0000000000878bda in io_handler_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#10 0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#11 0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 8 (LWP 2239):
+bt
#0  0x0000003da14e8bdf in poll () from /lib64/libc.so.6
#1  0x0000000000520ee2 in handle_connections_sockets () at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/mysqld.cc:5383
#2  0x0000000000522d60 in mysqld_main (argc=50, argv=0x3027288) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/mysqld.cc:4822
#3  0x0000000000518aa5 in main (argc=<optimized out>, argv=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/main.cc:25

Thread 7 (LWP 2245):
+bt
#0  0x0000003fa1400614 in ?? () from /lib64/libaio.so.1
#1  0x0000000000997787 in os_aio_linux_collect (seg_size=256, segment=2, array=0x344a260) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=global_seg@entry=4, message1=message1@entry=0x7f2ac99fce68, message2=message2@entry=0x7f2ac99fce60, type=type@entry=0x7f2ac99fce58, space_id=space_id@entry=0x7f2ac99fce50) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x0000000000939627 in fil_aio_wait (segment=segment@entry=4) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x0000000000878bda in io_handler_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#6  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 6 (LWP 2258):
+bt
#0  0x0000003da180b595 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x000000000099a275 in os_cond_wait (mutex=0x34526a0, cond=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=0x34526a0, reset_sig_count=92164, reset_sig_count@entry=0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x00000000009974d4 in os_aio_wait_until_no_pending_writes () at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:3774
#4  0x00000000008e966e in buf_flush_sync_datafiles () at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c:699
#5  0x00000000008eab7e in buf_flush_buffered_writes () at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c:937
#6  0x00000000008f0a3a in buf_flush_batch (buf_pool=buf_pool@entry=0x3474ef8, flush_type=flush_type@entry=BUF_FLUSH_LIST, min_n=min_n@entry=38, lsn_limit=lsn_limit@entry=5731437794) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c:1864
#7  0x00000000008f16fb in buf_flush_list (min_n=<optimized out>, min_n@entry=38, lsn_limit=lsn_limit@entry=5731437794) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0flu.c:2073
#8  0x0000000000876403 in srv_master_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0srv.c:3524
#9  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#10 0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 5 (LWP 2241):
+bt
#0  0x0000003fa1400614 in ?? () from /lib64/libaio.so.1
#1  0x0000000000997787 in os_aio_linux_collect (seg_size=256, segment=0, array=0x342ddb0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=global_seg@entry=0, message1=message1@entry=0x7f2acc7fee68, message2=message2@entry=0x7f2acc7fee60, type=type@entry=0x7f2acc7fee58, space_id=space_id@entry=0x7f2acc7fee50) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x0000000000939627 in fil_aio_wait (segment=segment@entry=0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x0000000000878bda in io_handler_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#6  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 4 (LWP 2251):
+bt
#0  0x0000003da180b595 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x000000000099a275 in os_cond_wait (mutex=0x32d9680, cond=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=0x32d9680, reset_sig_count=2036, reset_sig_count@entry=0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0sync.c:609
#3  0x0000000000874df9 in srv_redo_log_follow_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0srv.c:3080
#4  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#5  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 3 (LWP 2243):
+bt
#0  0x0000003fa1400614 in ?? () from /lib64/libaio.so.1
#1  0x0000000000997787 in os_aio_linux_collect (seg_size=256, segment=0, array=0x344a260) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=global_seg@entry=2, message1=message1@entry=0x7f2aca9fee68, message2=message2@entry=0x7f2aca9fee60, type=type@entry=0x7f2aca9fee58, space_id=space_id@entry=0x7f2aca9fee50) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x0000000000939627 in fil_aio_wait (segment=segment@entry=2) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x0000000000878bda in io_handler_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#6  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 2 (LWP 2244):
+bt
#0  0x0000003fa1400614 in ?? () from /lib64/libaio.so.1
#1  0x0000000000997787 in os_aio_linux_collect (seg_size=256, segment=1, array=0x344a260) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4681
#2  os_aio_linux_handle (global_seg=global_seg@entry=3, message1=message1@entry=0x7f2aca1fde68, message2=message2@entry=0x7f2aca1fde60, type=type@entry=0x7f2aca1fde58, space_id=space_id@entry=0x7f2aca1fde50) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/os/os0file.c:4826
#3  0x0000000000939627 in fil_aio_wait (segment=segment@entry=3) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:5559
#4  0x0000000000878bda in io_handler_thread (arg=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/srv/srv0start.c:485
#5  0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#6  0x0000003da14f168d in clone () from /lib64/libc.so.6

Thread 1 (LWP 24779):
+bt
#0  0x0000003da180c60c in pthread_kill () from /lib64/libpthread.so.0
#1  0x00000000007de9a8 in my_write_core (sig=6) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/mysys/stacktrace.c:433
#2  0x00000000006b3114 in handle_fatal_signal (sig=6) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/signal_handler.cc:249
#3  <signal handler called>
#4  0x0000003da1435935 in raise () from /lib64/libc.so.6
#5  0x0000003da14370e8 in abort () from /lib64/libc.so.6
#6  0x00000000008fdc21 in buf_flush_or_remove_pages (id=22999, buf_pool=0x3474ef8) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0lru.c:605
#7  buf_flush_dirty_pages (id=<optimized out>, buf_pool=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0lru.c:668
#8  buf_LRU_flush_or_remove_pages (id=id@entry=22999, buf_remove=buf_remove@entry=BUF_REMOVE_FLUSH_NO_WRITE) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/buf/buf0lru.c:864
#9  0x0000000000935050 in fil_delete_tablespace (id=id@entry=22999, evict_all=0, evict_all@entry=1) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/fil/fil0fil.c:2398
#10 0x0000000000846cbf in row_drop_table_for_mysql (name=0x7f2a18050888 "query02624/#sql2-8bf-5ee", trx=0x7f2a18089738, drop_db=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/row/row0mysql.c:3577
#11 0x000000000081cdb5 in ha_innobase::delete_table (this=<optimized out>, name=<optimized out>) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/storage/innobase/handler/ha_innodb.cc:8452
#12 0x00000000006b9a22 in handler::ha_delete_table (this=this@entry=0x7f2a1804af88, name=name@entry=0x7f2ab610e8a0 "./query02624/#sql2-8bf-5ee") at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/handler.cc:3660
#13 0x00000000006b9b1b in ha_delete_table (thd=0x39141a0, table_type=<optimized out>, path=0x7f2ab610e8a0 "./query02624/#sql2-8bf-5ee", db=0x7f2a1800d478 "query02624", alias=0x7f2ab610ecc0 "#sql2-8bf-5ee", generate_warning=false) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/handler.cc:2211
#14 0x000000000060141b in quick_rm_table (base=base@entry=0x30679b0, db=db@entry=0x7f2a1800d478 "query02624", table_name=table_name@entry=0x7f2ab610ecc0 "#sql2-8bf-5ee", flags=flags@entry=3) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:2416
#15 0x000000000060ba7a in mysql_alter_table (thd=<optimized out>, new_db=<optimized out>, new_name=0x7f2a1800d490 "t1", create_info=0x7f2ab6110230, table_list=0x7f2a1800d478, alter_info=0x7f2ab6110100, order_num=0, order=0x0, ignore=false) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_table.cc:7004
#16 0x00000000007bd089 in Alter_table_statement::execute (this=<optimized out>, thd=0x39141a0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_alter.cc:106
#17 0x00000000005a0b95 in mysql_execute_command (thd=thd@entry=0x39141a0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:4615
#18 0x00000000005a1f2d in mysql_parse (thd=thd@entry=0x39141a0, rawbuf=<optimized out>, length=47, parser_state=parser_state@entry=0x7f2ab6111760) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:5844
#19 0x00000000005a2a08 in dispatch_command (command=command@entry=COM_QUERY, thd=thd@entry=0x39141a0, packet=packet@entry=0x39172d1 "ALTER TABLE query02624 . `t1` DROP COLUMN `c30`", packet_length=packet_length@entry=47) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:1061
#20 0x00000000005a3fc3 in do_command (thd=0x39141a0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_parse.cc:788
#21 0x000000000064e11c in do_handle_one_connection (thd_arg=thd_arg@entry=0x39141a0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1497
#22 0x000000000064e212 in handle_one_connection (arg=0x39141a0) at /ssd/QA-16274-5.5-3/Percona-Server-5.5.28-rel29.3/sql/sql_connect.cc:1404
#23 0x0000003da1807d14 in start_thread () from /lib64/libpthread.so.0
#24 0x0000003da14f168d in clone () from /lib64/libc.so.6
(gdb) +quit