(gdb) info threads
  171 Thread 0x7f8bccd2a700 (LWP 23073)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  -- / --
  168 Thread 0x7f8a2e701700 (LWP 23076)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  167 Thread 0x7f8a2d6ff700 (LWP 23098)  0x00000031ad4d9093 in select () from /lib64/libc.so.6
  166 Thread 0x7f8a2cefe700 (LWP 23099)  0x00000031ad4d9093 in select () from /lib64/libc.so.6
  165 Thread 0x7f8a2c6fd700 (LWP 23100)  0x00000031ad4d9093 in select () from /lib64/libc.so.6
  164 Thread 0x7f8a2befc700 (LWP 23101)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  163 Thread 0x7f8a2b6fb700 (LWP 23102)  0x00000031ad80ec6c in sigwait () from /lib64/libpthread.so.0
  162 Thread 0x7f8a2ae18700 (LWP 5887)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  -- / --
  148 Thread 0x7f8a2ab0c700 (LWP 6248)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  147 Thread 0x7f8a2a800700 (LWP 6265)  0x000000000078aea7 in lock_rec_get_prev ()
  146 Thread 0x7f8a2a125700 (LWP 6278)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  -- / --
  135 Thread 0x7f8a28c12700 (LWP 6454)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
---Type <return> to continue, or q <return> to quit---
  134 Thread 0x7f8a29577700 (LWP 6466)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  -- / --
  113 Thread 0x7f8a25f58700 (LWP 30449)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  112 Thread 0x7f8a25fda700 (LWP 30458)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  111 Thread 0x7f8a28fe1700 (LWP 30461)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  -- / --
  98 Thread 0x7f8a2b5b6700 (LWP 30740)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
---Type <return> to continue, or q <return> to quit---
  97 Thread 0x7f8a28537700 (LWP 30752)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  -- / --
  90 Thread 0x7f8a287c1700 (LWP 30881)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  89 Thread 0x7f8a2a166700 (LWP 22280)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  88 Thread 0x7f8a2a36e700 (LWP 22283)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  -- / --
  84 Thread 0x7f8a25738700 (LWP 22465)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  83 Thread 0x7f8a2b4f3700 (LWP 22504)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  82 Thread 0x7f8a28c53700 (LWP 22514)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  81 Thread 0x7f8a28906700 (LWP 22535)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  80 Thread 0x7f8a28bd1700 (LWP 22538)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  -- / --
  77 Thread 0x7f8a2867c700 (LWP 22593)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  76 Thread 0x7f8a2aa8a700 (LWP 22612)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  75 Thread 0x7f8a2822b700 (LWP 22615)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  74 Thread 0x7f8a2a1e8700 (LWP 22638)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  73 Thread 0x7f8a258ff700 (LWP 22641)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  72 Thread 0x7f8a25e54700 (LWP 22650)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  71 Thread 0x7f8a25b89700 (LWP 22653)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  -- / --
  67 Thread 0x7f8a28d98700 (LWP 22730)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  66 Thread 0x7f8a29801700 (LWP 22742)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  65 Thread 0x7f8a2a021700 (LWP 22745)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  -- / --
  61 Thread 0x7f8a29d97700 (LWP 22806)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
---Type <return> to continue, or q <return> to quit---
  60 Thread 0x7f8a28370700 (LWP 22821)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  59 Thread 0x7f8a29d15700 (LWP 22844)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  58 Thread 0x7f8a282ad700 (LWP 22856)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  57 Thread 0x7f8a294b4700 (LWP 22871)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  56 Thread 0x7f8a26160700 (LWP 22883)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  55 Thread 0x7f8a292ed700 (LWP 6796)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  54 Thread 0x7f8a2826c700 (LWP 6799)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  53 Thread 0x7f8a28843700 (LWP 6805)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  52 Thread 0x7f8a281a9700 (LWP 6808)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  51 Thread 0x7f8a25530700 (LWP 6817)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  50 Thread 0x7f8a24e14700 (LWP 6820)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  49 Thread 0x7f8a27d99700 (LWP 6850)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  48 Thread 0x7f8a280e6700 (LWP 6853)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  47 Thread 0x7f8a2922a700 (LWP 6877)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  46 Thread 0x7f8a2aa08700 (LWP 6880)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  45 Thread 0x7f8a2a4f4700 (LWP 21943)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  44 Thread 0x7f8a254ae700 (LWP 21946)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  43 Thread 0x7f8a256b6700 (LWP 21966)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  42 Thread 0x7f8a2601b700 (LWP 21969)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  41 Thread 0x7f8a25940700 (LWP 21994)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  40 Thread 0x7f8a283b1700 (LWP 21997)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  39 Thread 0x7f8a25120700 (LWP 22269)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  38 Thread 0x7f8a280a5700 (LWP 22286)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  37 Thread 0x7f8a2b3ef700 (LWP 22540)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  36 Thread 0x7f8a2a5b7700 (LWP 22543)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  35 Thread 0x7f8a2587d700 (LWP 22574)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  34 Thread 0x7f8a250df700 (LWP 22583)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  33 Thread 0x7f8a254ef700 (LWP 22609)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  32 Thread 0x7f8a2a535700 (LWP 22617)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  31 Thread 0x7f8a2b679700 (LWP 22681)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  30 Thread 0x7f8a29946700 (LWP 22685)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  29 Thread 0x7f8a2926b700 (LWP 22834)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  28 Thread 0x7f8a24d92700 (LWP 22837)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  27 Thread 0x7f8a27d17700 (LWP 22874)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  26 Thread 0x7f8a29987700 (LWP 22877)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  25 Thread 0x7f8a24e55700 (LWP 22889)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  24 Thread 0x7f8a24c0c700 (LWP 22892)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
---Type <return> to continue, or q <return> to quit---
  23 Thread 0x7f8a25b48700 (LWP 22898)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  22 Thread 0x7f8a25c4c700 (LWP 22901)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  21 Thread 0x7f8a24fdb700 (LWP 22912)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  20 Thread 0x7f8a252e7700 (LWP 22915)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  19 Thread 0x7f8a25369700 (LWP 22923)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  18 Thread 0x7f8a24ed7700 (LWP 22926)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  17 Thread 0x7f8a252a6700 (LWP 22932)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  16 Thread 0x7f8a2501c700 (LWP 22935)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  15 Thread 0x7f8a24e96700 (LWP 22941)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  14 Thread 0x7f8a251a2700 (LWP 22944)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  13 Thread 0x7f8a25265700 (LWP 22965)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  12 Thread 0x7f8a25224700 (LWP 22968)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  11 Thread 0x7f8a253eb700 (LWP 2043)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  10 Thread 0x7f8a28a8c700 (LWP 2046)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  9 Thread 0x7f8a28b4f700 (LWP 2054)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  8 Thread 0x7f8a25634700 (LWP 2057)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  7 Thread 0x7f8a24f59700 (LWP 2453)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  6 Thread 0x7f8a24f18700 (LWP 2456)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  5 Thread 0x7f8a245b3700 (LWP 2733)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  4 Thread 0x7f8a24572700 (LWP 2785)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  3 Thread 0x7f8a29c52700 (LWP 31067)  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
  2 Thread 0x7f8a2a841700 (LWP 23729)  0x00000031ad80b3b4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
* 1 Thread 0x7f8bccd2c800 (LWP 23071)  0x00000031ad4d9093 in select () from /lib64/libc.so.6
(gdb)
(gdb) t 3
[Switching to thread 3 (Thread 0x7f8a29c52700 (LWP 31067))]#0  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
(gdb) bt
#0  0x00000031ad80df7d in read () from /lib64/libpthread.so.0
#1  0x00000000005b3e37 in ?? ()
#2  0x00000000005b4c7d in my_net_read ()
#3  0x00000000005d4c96 in do_command(THD*) ()
#4  0x00000000005c666d in handle_one_connection ()
#5  0x00000031ad806ccb in start_thread () from /lib64/libpthread.so.0
#6  0x00000031ad4e0c2d in clone () from /lib64/libc.so.6
(gdb) t 147
[Switching to thread 147 (Thread 0x7f8a2a800700 (LWP 6265))]#0  0x000000000078aea7 in lock_rec_get_prev ()
(gdb) bt
#0  0x000000000078aea7 in lock_rec_get_prev ()
#1  0x000000000078f4ee in ?? ()
#2  0x000000000078f537 in ?? ()
#3  0x000000000078f823 in ?? ()
#4  0x000000000078f9bb in ?? ()
#5  0x0000000000792d4a in lock_sec_rec_read_check_and_lock ()
#6  0x00000000007c54a9 in ?? ()
#7  0x00000000007c9ec2 in row_search_for_mysql ()
#8  0x00000000007386ff in ha_innobase::index_read(unsigned char*, unsigned char const*, unsigned int, ha_rkey_function) ()
#9  0x000000000062a885 in ?? ()
#10 0x000000000061db63 in sub_select(JOIN*, st_join_table*, bool) ()
#11 0x0000000000629665 in ?? ()
#12 0x0000000000639234 in JOIN::exec() ()
#13 0x0000000000634c78 in mysql_select(THD*, Item***, TABLE_LIST*, unsigned int, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*) ()
#14 0x00000000006f22e1 in mysql_derived_filling(THD*, st_lex*, TABLE_LIST*) ()
#15 0x00000000006f1d98 in mysql_handle_derived(st_lex*, bool (*)(THD*, st_lex*, TABLE_LIST*)) ()
#16 0x000000000064e59f in mysql_multi_update_prepare(THD*) ()
#17 0x00000000005ccf57 in mysql_execute_command(THD*) ()
#18 0x00000000005d3413 in mysql_parse(THD*, char*, unsigned int, char const**) ()
#19 0x00000000005d413b in dispatch_command(enum_server_command, THD*, char*, unsigned int) ()
#20 0x00000000005d4cfa in do_command(THD*) ()
#21 0x00000000005c666d in handle_one_connection ()
#22 0x00000031ad806ccb in start_thread () from /lib64/libpthread.so.0
#23 0x00000031ad4e0c2d in clone () from /lib64/libc.so.6
(gdb) c
Continuing.