Memory anomaly revealed by Valgrind

The information below came from a long Valgrind run aimed at checking MXS-329. This seems a minor problem, and it is not clear that it is related to MXS-329. So rather than attempting to tackle it as part of the work on MXS-329 I have created another bug report.

==10958== Thread 4:
==10958== Invalid read of size 4
==10958==    at 0x554EF8: dcb_write (dcb.c:1197)
==10958==    by 0x1D7A3E35: gw_MySQLWrite_client (mysql_client.c:636)
==10958==    by 0x1C36FC53: handleError (readconnroute.c:882)
==10958==    by 0x213C1808: gw_backend_hangup (mysql_backend.c:1141)
==10958==    by 0x1C3700E8: handle_state_switch (readconnroute.c:1034)
==10958==    by 0x5590D7: dcb_call_callback (dcb.c:2694)
==10958==    by 0x559320: dcb_call_foreach (dcb.c:2808)
==10958==    by 0x1C9948D0: monitorMain (mysql_mon.c:864)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==  Address 0xa4d7680 is 272 bytes inside a block of size 448 free'd
==10958==    at 0x4C27430: free (vg_replace_malloc.c:446)
==10958==    by 0x552854: dcb_final_free (dcb.c:392)
==10958==    by 0x55308C: dcb_process_victim_queue (dcb.c:630)
==10958==    by 0x552B6A: dcb_process_zombies (dcb.c:509)
==10958==    by 0x565EB5: poll_waitevents (poll.c:697)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==
==10958== Invalid write of size 4
==10958==    at 0x554F05: dcb_write (dcb.c:1197)
==10958==    by 0x1D7A3E35: gw_MySQLWrite_client (mysql_client.c:636)
==10958==    by 0x1C36FC53: handleError (readconnroute.c:882)
==10958==    by 0x213C1808: gw_backend_hangup (mysql_backend.c:1141)
==10958==    by 0x1C3700E8: handle_state_switch (readconnroute.c:1034)
==10958==    by 0x5590D7: dcb_call_callback (dcb.c:2694)
==10958==    by 0x559320: dcb_call_foreach (dcb.c:2808)
==10958==    by 0x1C9948D0: monitorMain (mysql_mon.c:864)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==  Address 0xa4d7680 is 272 bytes inside a block of size 448 free'd
==10958==    at 0x4C27430: free (vg_replace_malloc.c:446)
==10958==    by 0x552854: dcb_final_free (dcb.c:392)
==10958==    by 0x55308C: dcb_process_victim_queue (dcb.c:630)
==10958==    by 0x552B6A: dcb_process_zombies (dcb.c:509)
==10958==    by 0x565EB5: poll_waitevents (poll.c:697)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==
==10958== Invalid read of size 4
==10958==    at 0x555852: dcb_log_write_failure (dcb.c:1400)
==10958==    by 0x554F40: dcb_write (dcb.c:1205)
==10958==    by 0x1D7A3E35: gw_MySQLWrite_client (mysql_client.c:636)
==10958==    by 0x1C36FC53: handleError (readconnroute.c:882)
==10958==    by 0x213C1808: gw_backend_hangup (mysql_backend.c:1141)
==10958==    by 0x1C3700E8: handle_state_switch (readconnroute.c:1034)
==10958==    by 0x5590D7: dcb_call_callback (dcb.c:2694)
==10958==    by 0x559320: dcb_call_foreach (dcb.c:2808)
==10958==    by 0x1C9948D0: monitorMain (mysql_mon.c:864)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==  Address 0xa4d75b0 is 64 bytes inside a block of size 448 free'd
==10958==    at 0x4C27430: free (vg_replace_malloc.c:446)
==10958==    by 0x552854: dcb_final_free (dcb.c:392)
==10958==    by 0x55308C: dcb_process_victim_queue (dcb.c:630)
==10958==    by 0x552B6A: dcb_process_zombies (dcb.c:509)
==10958==    by 0x565EB5: poll_waitevents (poll.c:697)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==
==10958== Invalid read of size 4
==10958==    at 0x55585C: dcb_log_write_failure (dcb.c:1400)
==10958==    by 0x554F40: dcb_write (dcb.c:1205)
==10958==    by 0x1D7A3E35: gw_MySQLWrite_client (mysql_client.c:636)
==10958==    by 0x1C36FC53: handleError (readconnroute.c:882)
==10958==    by 0x213C1808: gw_backend_hangup (mysql_backend.c:1141)
==10958==    by 0x1C3700E8: handle_state_switch (readconnroute.c:1034)
==10958==    by 0x5590D7: dcb_call_callback (dcb.c:2694)
==10958==    by 0x559320: dcb_call_foreach (dcb.c:2808)
==10958==    by 0x1C9948D0: monitorMain (mysql_mon.c:864)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==  Address 0xa4d75b4 is 68 bytes inside a block of size 448 free'd
==10958==    at 0x4C27430: free (vg_replace_malloc.c:446)
==10958==    by 0x552854: dcb_final_free (dcb.c:392)
==10958==    by 0x55308C: dcb_process_victim_queue (dcb.c:630)
==10958==    by 0x552B6A: dcb_process_zombies (dcb.c:509)
==10958==    by 0x565EB5: poll_waitevents (poll.c:697)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==
==10958== Invalid read of size 4
==10958==    at 0x55586F: dcb_log_write_failure (dcb.c:1400)
==10958==    by 0x554F40: dcb_write (dcb.c:1205)
==10958==    by 0x1D7A3E35: gw_MySQLWrite_client (mysql_client.c:636)
==10958==    by 0x1C36FC53: handleError (readconnroute.c:882)
==10958==    by 0x213C1808: gw_backend_hangup (mysql_backend.c:1141)
==10958==    by 0x1C3700E8: handle_state_switch (readconnroute.c:1034)
==10958==    by 0x5590D7: dcb_call_callback (dcb.c:2694)
==10958==    by 0x559320: dcb_call_foreach (dcb.c:2808)
==10958==    by 0x1C9948D0: monitorMain (mysql_mon.c:864)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==  Address 0xa4d75b4 is 68 bytes inside a block of size 448 free'd
==10958==    at 0x4C27430: free (vg_replace_malloc.c:446)
==10958==    by 0x552854: dcb_final_free (dcb.c:392)
==10958==    by 0x55308C: dcb_process_victim_queue (dcb.c:630)
==10958==    by 0x552B6A: dcb_process_zombies (dcb.c:509)
==10958==    by 0x565EB5: poll_waitevents (poll.c:697)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==
==10958== Invalid read of size 4
==10958==    at 0x555882: dcb_log_write_failure (dcb.c:1400)
==10958==    by 0x554F40: dcb_write (dcb.c:1205)
==10958==    by 0x1D7A3E35: gw_MySQLWrite_client (mysql_client.c:636)
==10958==    by 0x1C36FC53: handleError (readconnroute.c:882)
==10958==    by 0x213C1808: gw_backend_hangup (mysql_backend.c:1141)
==10958==    by 0x1C3700E8: handle_state_switch (readconnroute.c:1034)
==10958==    by 0x5590D7: dcb_call_callback (dcb.c:2694)
==10958==    by 0x559320: dcb_call_foreach (dcb.c:2808)
==10958==    by 0x1C9948D0: monitorMain (mysql_mon.c:864)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==  Address 0xa4d75b4 is 68 bytes inside a block of size 448 free'd
==10958==    at 0x4C27430: free (vg_replace_malloc.c:446)
==10958==    by 0x552854: dcb_final_free (dcb.c:392)
==10958==    by 0x55308C: dcb_process_victim_queue (dcb.c:630)
==10958==    by 0x552B6A: dcb_process_zombies (dcb.c:509)
==10958==    by 0x565EB5: poll_waitevents (poll.c:697)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==
==10958== Invalid read of size 4
==10958==    at 0x555891: dcb_log_write_failure (dcb.c:1400)
==10958==    by 0x554F40: dcb_write (dcb.c:1205)
==10958==    by 0x1D7A3E35: gw_MySQLWrite_client (mysql_client.c:636)
==10958==    by 0x1C36FC53: handleError (readconnroute.c:882)
==10958==    by 0x213C1808: gw_backend_hangup (mysql_backend.c:1141)
==10958==    by 0x1C3700E8: handle_state_switch (readconnroute.c:1034)
==10958==    by 0x5590D7: dcb_call_callback (dcb.c:2694)
==10958==    by 0x559320: dcb_call_foreach (dcb.c:2808)
==10958==    by 0x1C9948D0: monitorMain (mysql_mon.c:864)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==  Address 0xa4d75b4 is 68 bytes inside a block of size 448 free'd
==10958==    at 0x4C27430: free (vg_replace_malloc.c:446)
==10958==    by 0x552854: dcb_final_free (dcb.c:392)
==10958==    by 0x55308C: dcb_process_victim_queue (dcb.c:630)
==10958==    by 0x552B6A: dcb_process_zombies (dcb.c:509)
==10958==    by 0x565EB5: poll_waitevents (poll.c:697)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==
==10958== Invalid read of size 4
==10958==    at 0x54A416: atomic_add (atomic.c:51)
==10958==    by 0x554F61: dcb_write (dcb.c:1211)
==10958==    by 0x1D7A3E35: gw_MySQLWrite_client (mysql_client.c:636)
==10958==    by 0x1C36FC53: handleError (readconnroute.c:882)
==10958==    by 0x213C1808: gw_backend_hangup (mysql_backend.c:1141)
==10958==    by 0x1C3700E8: handle_state_switch (readconnroute.c:1034)
==10958==    by 0x5590D7: dcb_call_callback (dcb.c:2694)
==10958==    by 0x559320: dcb_call_foreach (dcb.c:2808)
==10958==    by 0x1C9948D0: monitorMain (mysql_mon.c:864)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==  Address 0xa4d7650 is 224 bytes inside a block of size 448 free'd
==10958==    at 0x4C27430: free (vg_replace_malloc.c:446)
==10958==    by 0x552854: dcb_final_free (dcb.c:392)
==10958==    by 0x55308C: dcb_process_victim_queue (dcb.c:630)
==10958==    by 0x552B6A: dcb_process_zombies (dcb.c:509)
==10958==    by 0x565EB5: poll_waitevents (poll.c:697)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==
==10958== Invalid write of size 8
==10958==    at 0x554F6A: dcb_write (dcb.c:1212)
==10958==    by 0x1D7A3E35: gw_MySQLWrite_client (mysql_client.c:636)
==10958==    by 0x1C36FC53: handleError (readconnroute.c:882)
==10958==    by 0x213C1808: gw_backend_hangup (mysql_backend.c:1141)
==10958==    by 0x1C3700E8: handle_state_switch (readconnroute.c:1034)
==10958==    by 0x5590D7: dcb_call_callback (dcb.c:2694)
==10958==    by 0x559320: dcb_call_foreach (dcb.c:2808)
==10958==    by 0x1C9948D0: monitorMain (mysql_mon.c:864)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==  Address 0xa4d7658 is 232 bytes inside a block of size 448 free'd
==10958==    at 0x4C27430: free (vg_replace_malloc.c:446)
==10958==    by 0x552854: dcb_final_free (dcb.c:392)
==10958==    by 0x55308C: dcb_process_victim_queue (dcb.c:630)
==10958==    by 0x552B6A: dcb_process_zombies (dcb.c:509)
==10958==    by 0x565EB5: poll_waitevents (poll.c:697)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==
==10958== Invalid read of size 4
==10958==    at 0x554F75: dcb_write (dcb.c:1213)
==10958==    by 0x1D7A3E35: gw_MySQLWrite_client (mysql_client.c:636)
==10958==    by 0x1C36FC53: handleError (readconnroute.c:882)
==10958==    by 0x213C1808: gw_backend_hangup (mysql_backend.c:1141)
==10958==    by 0x1C3700E8: handle_state_switch (readconnroute.c:1034)
==10958==    by 0x5590D7: dcb_call_callback (dcb.c:2694)
==10958==    by 0x559320: dcb_call_foreach (dcb.c:2808)
==10958==    by 0x1C9948D0: monitorMain (mysql_mon.c:864)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==  Address 0xa4d7688 is 280 bytes inside a block of size 448 free'd
==10958==    at 0x4C27430: free (vg_replace_malloc.c:446)
==10958==    by 0x552854: dcb_final_free (dcb.c:392)
==10958==    by 0x55308C: dcb_process_victim_queue (dcb.c:630)
==10958==    by 0x552B6A: dcb_process_zombies (dcb.c:509)
==10958==    by 0x565EB5: poll_waitevents (poll.c:697)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==
==10958== Invalid write of size 4
==10958==    at 0x554F82: dcb_write (dcb.c:1213)
==10958==    by 0x1D7A3E35: gw_MySQLWrite_client (mysql_client.c:636)
==10958==    by 0x1C36FC53: handleError (readconnroute.c:882)
==10958==    by 0x213C1808: gw_backend_hangup (mysql_backend.c:1141)
==10958==    by 0x1C3700E8: handle_state_switch (readconnroute.c:1034)
==10958==    by 0x5590D7: dcb_call_callback (dcb.c:2694)
==10958==    by 0x559320: dcb_call_foreach (dcb.c:2808)
==10958==    by 0x1C9948D0: monitorMain (mysql_mon.c:864)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==  Address 0xa4d7688 is 280 bytes inside a block of size 448 free'd
==10958==    at 0x4C27430: free (vg_replace_malloc.c:446)
==10958==    by 0x552854: dcb_final_free (dcb.c:392)
==10958==    by 0x55308C: dcb_process_victim_queue (dcb.c:630)
==10958==    by 0x552B6A: dcb_process_zombies (dcb.c:509)
==10958==    by 0x565EB5: poll_waitevents (poll.c:697)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==
==10958== Invalid write of size 4
==10958==    at 0x54C305: spinlock_release (spinlock.c:132)
==10958==    by 0x554F99: dcb_write (dcb.c:1214)
==10958==    by 0x1D7A3E35: gw_MySQLWrite_client (mysql_client.c:636)
==10958==    by 0x1C36FC53: handleError (readconnroute.c:882)
==10958==    by 0x213C1808: gw_backend_hangup (mysql_backend.c:1141)
==10958==    by 0x1C3700E8: handle_state_switch (readconnroute.c:1034)
==10958==    by 0x5590D7: dcb_call_callback (dcb.c:2694)
==10958==    by 0x559320: dcb_call_foreach (dcb.c:2808)
==10958==    by 0x1C9948D0: monitorMain (mysql_mon.c:864)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==  Address 0xa4d7654 is 228 bytes inside a block of size 448 free'd
==10958==    at 0x4C27430: free (vg_replace_malloc.c:446)
==10958==    by 0x552854: dcb_final_free (dcb.c:392)
==10958==    by 0x55308C: dcb_process_victim_queue (dcb.c:630)
==10958==    by 0x552B6A: dcb_process_zombies (dcb.c:509)
==10958==    by 0x565EB5: poll_waitevents (poll.c:697)
==10958==    by 0x59319D0: start_thread (in /lib64/libpthread-2.12.so)
==10958==    by 0x700B8FC: clone (in /lib64/libc-2.12.so)
==10958==