Comment 23 for bug 1729536

Unfortunately, we had big hopes but we experienced again this exact bug, with the exact same trace for version 5.1.21.

+-----------------------------+
| VERSION() |
+-----------------------------+
| 5.7.21-0ubuntu0.16.04.1-log |
+-----------------------------+

Trace found in error.log:

2018-03-16 05:53:38 0x7f8e4a4bf700 InnoDB: Assertion failure in thread 140249108576000 in file pars0pars.cc line 822
InnoDB: Failing assertion: sym_node->table != NULL
InnoDB: We intentionally generate a memory trap.
InnoDB: Submit a detailed bug report to http://bugs.mysql.com.
InnoDB: If you get repeated assertion failures or crashes, even
InnoDB: immediately after the mysqld startup, there may be
InnoDB: corruption in the InnoDB tablespace. Please refer to
InnoDB: http://dev.mysql.com/doc/refman/5.7/en/forcing-innodb-recovery.html
InnoDB: about forcing recovery.
04:53:38 UTC - mysqld got signal 6 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
Attempting to collect some information that could help diagnose the problem.
As this is a crash and something is definitely wrong, the information
collection process might fail.

key_buffer_size=16777216
read_buffer_size=131072
max_used_connections=0
max_threads=214
thread_count=7
connection_count=0
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 101418 K bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x0
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
stack_bottom = 0 thread_stack 0x30000
/usr/sbin/mysqld(my_print_stacktrace+0x3b)[0xe8f29b]
/usr/sbin/mysqld(handle_fatal_signal+0x489)[0x787029]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x11390)[0x7fb5700bc390]
/lib/x86_64-linux-gnu/libc.so.6(gsignal+0x38)[0x7fb56f475428]
/lib/x86_64-linux-gnu/libc.so.6(abort+0x16a)[0x7fb56f47702a]
/usr/sbin/mysqld[0x75ca3e]
/usr/sbin/mysqld(_Z21pars_insert_statementP10sym_node_tPvP10sel_node_t+0x3a8)[0xf62a08]
/usr/sbin/mysqld(_Z7yyparsev+0x1227)[0x11839a7]
/usr/sbin/mysqld(_Z8pars_sqlP11pars_info_tPKc+0x9e)[0xf6425e]
/usr/sbin/mysqld(_Z13fts_parse_sqlP11fts_table_tP11pars_info_tPKc+0x190)[0x11635b0]
/usr/sbin/mysqld(_Z14fts_write_nodeP5trx_tPP10que_fork_tP11fts_table_tP12fts_string_tP10fts_node_t+0x292)[0x113ddb2]
/usr/sbin/mysqld[0x1141568]
/usr/sbin/mysqld(_Z14fts_sync_tableP12dict_table_tbbb+0x329)[0x11475b9]
/usr/sbin/mysqld(_Z23fts_optimize_sync_tablem+0x42)[0x114ef02]
/usr/sbin/mysqld(_Z19fts_optimize_threadPv+0x57c)[0x115845c]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x76ba)[0x7fb5700b26ba]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7fb56f54741d]
The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains
information that should help you find out what is causing the crash.

We recovered the replication by skipping the duplicate entries that were apparently already processed.