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MariaDB 10.3 crashing and restarting intermittently - segfault at 0

Hello,

We are using a Debian 10 server with MariaDB 10.3.27. It use to work nice, but since 1 week, we are facing some regular crashes after a few hours of run. Then applications (zabbix, etc...) loss the DB connections and some transactions are broken.

System specs : - 2 vCPU - 10G of RAM - Disks are some LUNs on an EMC VNX

Here is an example of the syslog messages:

Dec 14 16:05:08 mysqlbddvprd1 kernel: [503847.749484] show_signal_msg: 18 callbacks suppressed
Dec 14 16:05:08 mysqlbddvprd1 kernel: [503847.749487] mysqld[60145]: segfault at 0 ip 0000557197badfb3 sp 00007f2dbbe2d310 error 6 in mysqld[5571973f0000+80a000]
Dec 14 16:05:08 mysqlbddvprd1 kernel: [503847.749491] Code: c7 45 00 00 00 00 00 8b 7d cc 4c 89 e2 4c 89 f6 e8 52 2f 84 ff 49 89 c7 49 39 c4 0f 84 06 01 00 00 e8 21 18 00 00 41 8b 4d 00 <89> 08 85 c9 74 37 49 83 ff ff 0f 84 ad 00 00 00 f6 c3 06 75 28 4d
Dec 14 16:05:08 mysqlbddvprd1 systemd[1]: mariadb.service: Main process exited, code=killed, status=11/SEGV
Dec 14 16:05:08 mysqlbddvprd1 systemd[1]: mariadb.service: Failed with result 'signal'.
Dec 14 16:05:13 mysqlbddvprd1 systemd[1]: mariadb.service: Service RestartSec=5s expired, scheduling restart.
Dec 14 16:05:13 mysqlbddvprd1 systemd[1]: mariadb.service: Scheduled restart job, restart counter is at 5.
Dec 14 16:05:13 mysqlbddvprd1 systemd[1]: Stopped MariaDB 10.3.27 database server.

Dec 14 16:05:13 mysqlbddvprd1 systemd[1]: Starting MariaDB 10.3.27 database server...
Dec 14 16:05:14 mysqlbddvprd1 sssd[be[ad.mediapost.fr]]: GSSAPI Error: Unspecified GSS failure.  Minor code may provide more information (Server not found in Kerberos database)
Dec 14 16:05:14 mysqlbddvprd1 mysqld[52124]: 2020-12-14 16:05:14 0 [Note] /usr/sbin/mysqld (mysqld 10.3.27-MariaDB-0+deb10u1) starting as process 52124 ...
Dec 14 16:05:23 mysqlbddvprd1 systemd[1]: Started MariaDB 10.3.27 database server.

Dec 14 16:05:23 mysqlbddvprd1 /etc/mysql/debian-start[52181]: Upgrading MySQL tables if necessary.
Dec 14 16:05:23 mysqlbddvprd1 /etc/mysql/debian-start[52184]: /usr/bin/mysql_upgrade: the '--basedir' option is always ignored
Dec 14 16:05:23 mysqlbddvprd1 /etc/mysql/debian-start[52184]: Looking for 'mysql' as: /usr/bin/mysql
Dec 14 16:05:23 mysqlbddvprd1 /etc/mysql/debian-start[52184]: Looking for 'mysqlcheck' as: /usr/bin/mysqlcheck
Dec 14 16:05:23 mysqlbddvprd1 /etc/mysql/debian-start[52184]: Version check failed. Got the following error when calling the 'mysql' command line client
Dec 14 16:05:23 mysqlbddvprd1 /etc/mysql/debian-start[52184]: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
Dec 14 16:05:23 mysqlbddvprd1 /etc/mysql/debian-start[52184]: FATAL ERROR: Upgrade failed
Dec 14 16:05:23 mysqlbddvprd1 /etc/mysql/debian-start[52197]: Checking for insecure root accounts.
Dec 14 16:05:23 mysqlbddvprd1 debian-start[52179]: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
Dec 14 16:09:01 mysqlbddvprd1 CRON[52474]: (root) CMD (  [ -x /usr/lib/php/sessionclean ] && if [ ! -d /run/systemd/system ]; then /usr/lib/php/sessionclean; fi)
Dec 14 16:09:01 mysqlbddvprd1 systemd[1]: Starting Clean php session files...
Dec 14 16:09:02 mysqlbddvprd1 systemd[1]: phpsessionclean.service: Succeeded.
Dec 14 16:09:02 mysqlbddvprd1 systemd[1]: Started Clean php session files.

And here is a part of the conf file we use: /etc/mysql/mariadb.conf.d/50-server.cnf

#
# * Fine Tuning
#
key_buffer_size         = 20M
max_allowed_packet      = 16M
thread_stack            = 192K
thread_cache_size       = 8
# This replaces the startup script and checks MyISAM tables if needed the first time they are touched
myisam_recover_options  = BACKUP
max_connections         = 100
#table_cache            = 64
#thread_concurrency     = 10

#
# * Fine Tuning for InnoDB
#
innodb_buffer_pool_size = 7G            # Go up to 70% to 80% of your available RAM
innodb_buffer_pool_instances = 4        # Bigger if huge InnoDB Buffer Pool or high concurrency

innodb_file_per_table   = 1             # Is the recommended way nowadays
innodb_flush_method     = O_DIRECT
innodb_write_io_threads = 8             # If you have a strong I/O system or SSD
innodb_read_io_threads  = 8             # If you have a strong I/O system or SSD
innodb_io_capacity      = 1000          # If you have a strong I/O system or SSD

innodb_flush_log_at_trx_commit = 1      # 1 for durability, 0 or 2 for performance
innodb_log_buffer_size  = 8M            # Bigger if innodb_flush_log_at_trx_commit = 0
innodb_log_file_size    = 128M          # Bigger means more write throughput but longer recovery time

#
# * Query Cache Configuration
#
query_cache_limit       = 1M
query_cache_size        = 16M

Any comments are welcome.

Best regards,

Answer Answered by Daniel Black in this comment.

Please do a bug report on jira. Information from the mariadb error log (journalctl -n 40 mariadb.server) that includes from the mariadb start until the crash will be required. Data structures (`show create table {tablename}`) or any query causing the crash along with `EXPLAIN {query}` will assist our investigation.

Note on your config, its generally recommended to disable the query_cache unless you have tested and can show a benefit.

mysql/debian-start errors can be fixed by ensuring the root user has unix_socket authentication or have a user,password in /etc/mysql/debian.cnf for the use by this script.

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