signal 6

Hi. We have an active server
We confirmed signal 6.
The relevant logs are:
dict / dict0dict.cc: 1303 (I see dict_table_add_to_cache ~.
I want to know if signal 6 has occurred for some reason.
Thank you for your help.
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Version: '10.0.21-MariaDB-log' socket: '/data/mariadata/mysql.sock' port: 3306 MariaDB Server
181018 11:31:32 [Note] Slave SQL thread initialized, starting replication in log 'mysql-bin.000032' at position 5084466, relay log '/data/marialog/relay/mysql-relay.000082' position: 5084753
181018 11:31:32 [Note] Slave I/O thread: connected to master 'repl@10.65.7.109:3306',replication started in log 'mysql-bin.000032' at position 6519273
181018 11:36:18 [Note] 'CHANGE MASTER TO executed'. Previous state master_host='', master_port='3306', master_log_file='', master_log_pos='4'. New state master_host='10.65.7.109', master_port='3306', master_log_file='mysql-bin.000036', master_log_pos='378444869'.
181018 11:36:20 [Note] Slave SQL thread initialized, starting replication in log 'mysql-bin.000036' at position 378444869, relay log '/data/marialog/relay/mysql-relay.000001' position: 4

2018-10-18 11:59:54 7f6f4b3ff700 InnoDB: Assertion failure in thread 140115980580608 in file dict0dict.cc line 1303
InnoDB: Failing assertion: table2 == 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/5.6/en/forcing-innodb-recovery.html
InnoDB: about forcing recovery.
181018 11:59:54 [ERROR] 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.

To report this bug, see http://kb.askmonty.org/en/reporting-bugs

We will try our best to scrape up some info that will hopefully help
diagnose the problem, but since we have already crashed,
something is definitely wrong and this may fail.

Server version: 10.0.21-MariaDB-log
key_buffer_size=33554432
read_buffer_size=1048576
max_used_connections=6
max_threads=1002
thread_count=4
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 2104641 K bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x0x7f6f5733f008
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 = 0x7f6f4b3fee10 thread_stack 0x48000
mysys/stacktrace.c:247(my_print_stacktrace)[0xbce56e]
sql/signal_handler.cc:153(handle_fatal_signal)[0x7202cc]
/lib64/libpthread.so.0(+0xf7e0)[0x7f719ed567e0]
/lib64/libc.so.6(gsignal+0x35)[0x7f719dc17495]
/lib64/libc.so.6(abort+0x175)[0x7f719dc18c75]
dict/dict0dict.cc:1303(dict_table_add_to_cache(dict_table_t*, unsigned long, mem_block_info_t*))[0x9e8316]
include/mem0mem.ic:282(mem_heap_free_heap_top)[0x9f6948]
dict/dict0dict.cc:1142(dict_table_open_on_name(char const*, unsigned long, unsigned long, dict_err_ignore_t))[0x9ede59]
handler/ha_innodb.cc:5676(ha_innobase::open(char const*, int, unsigned int))[0x8b8301]
sql/handler.cc:2524(handler::ha_open(TABLE*, char const*, int, unsigned int))[0x72715e]
sql/table.cc:2882(open_table_from_share(THD*, TABLE_SHARE*, char const*, unsigned int, unsigned int, unsigned int, TABLE*, bool))[0x645001]
sql/sql_base.cc:2516(open_table(THD*, TABLE_LIST*, st_mem_root*, Open_table_context*))[0x556b69]
sql/sql_base.cc:4032(open_and_process_table)[0x5592ba]
sql/sql_base.cc:5209(open_and_lock_tables(THD*, TABLE_LIST*, bool, unsigned int, Prelocking_strategy*))[0x55960b]
sql/sql_parse.cc:5219(execute_sqlcom_select)[0x595f07]
sql/sql_parse.cc:2562(mysql_execute_command(THD*))[0x598b37]
sql/sql_parse.cc:6531(mysql_parse(THD*, char*, unsigned int, Parser_state*))[0x59ff76]
sql/sql_parse.cc:1310(dispatch_command(enum_server_command, THD*, char*, unsigned int))[0x5a1ea7]
sql/sql_parse.cc:999(do_command(THD*))[0x5a25e9]
sql/sql_connect.cc:1378(do_handle_one_connection(THD*))[0x66cf94]
sql/sql_connect.cc:1295(handle_one_connection)[0x66d0d2]
/lib64/libpthread.so.0(+0x7aa1)[0x7f719ed4eaa1]
/lib64/libc.so.6(clone+0x6d)[0x7f719dccdbcd]

Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (0x7f6f4ac22020): is an invalid pointer
Connection ID (thread ID): 33
Status: NOT_KILLED

Optimizer switch: index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on,extended_keys=on,exists_to_in=on

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.
181018 11:59:55 mysqld_safe Number of processes running now: 0
181018 11:59:55 mysqld_safe mysqld restarted
181018 11:59:55 [Note] /data/maria/bin/mysqld (mysqld 10.0.21-MariaDB-log) starting as process 1390 ...
181018 11:59:55 [Note] InnoDB: Using mutexes to ref count buffer pool pages
181018 11:59:55 [Note] InnoDB: The InnoDB memory heap is disabled
181018 11:59:55 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
181018 11:59:55 [Note] InnoDB: Memory barrier is not used
181018 11:59:55 [Note] InnoDB: Compressed tables use zlib 1.2.3
181018 11:59:55 [Note] InnoDB: Using Linux native AIO
181018 11:59:55 [Note] InnoDB: Using CPU crc32 instructions
181018 11:59:55 [Note] InnoDB: Initializing buffer pool, size = 8.0G
181018 11:59:56 [Note] InnoDB: Completed initialization of buffer pool
181018 11:59:56 [Note] InnoDB: Highest supported file format is Barracuda.
181018 11:59:56 [Note] InnoDB: Log scan progressed past the checkpoint lsn 154629623350
181018 11:59:56 [Note] InnoDB: Database was not shutdown normally!
181018 11:59:56 [Note] InnoDB: Starting crash recovery.
181018 11:59:56 [Note] InnoDB: Reading tablespace information from the .ibd files...
181018 11:59:57 [Note] InnoDB: Restoring possible half-written data pages
181018 11:59:57 [Note] InnoDB: from the doublewrite buffer...
InnoDB: Doing recovery: scanned up to log sequence number 154629623841
181018 11:59:57 [Note] InnoDB: Starting an apply batch of log records to the database...
InnoDB: Progress in percent: 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
InnoDB: Apply batch completed
InnoDB: Last MySQL binlog file position 0 1924, file name /data/marialog/binary/mysql-bin.000014
181018 11:59:59 [Note] InnoDB: 128 rollback segment(s) are active.
181018 11:59:59 [Note] InnoDB: Waiting for purge to start
181018 11:59:59 [Note] InnoDB: Percona XtraDB (http://www.percona.com) 5.6.25-73.1 started; log sequence number 154629623841
181018 11:59:59 [Note] Plugin 'FEEDBACK' is disabled.
181018 11:59:59 [Note] Recovering after a crash using /data/marialog/binary/mysql-bin
181018 11:59:59 [Note] Starting crash recovery...
181018 11:59:59 [Note] Crash recovery finished.
181018 11:59:59 [Note] Server socket created on IP: '::'.
181018 11:59:59 [Note] Event Scheduler: Loaded 4 events
181018 11:59:59 [Note] /data/maria/bin/mysqld: ready for connections.
Version: '10.0.21-MariaDB-log' socket: '/data/mariadata/mysql.sock' port: 3306 MariaDB Server