MySQL keeps crashing recently, error log
2020-10-24 19:04:44 18128 [Note] Plugin 'FEDERATED' is disabled.
2020-10-24 19:04:44 18128 [Note] InnoDB: Using atomics to ref count buffer pool pages
2020-10-24 19:04:44 18128 [Note] InnoDB: The InnoDB memory heap is disabled
2020-10-24 19:04:44 18128 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2020-10-24 19:04:44 18128 [Note] InnoDB: Memory barrier is not used
2020-10-24 19:04:44 18128 [Note] InnoDB: Compressed tables use zlib 1.2.11
2020-10-24 19:04:44 18128 [Note] InnoDB: Using Linux native AIO
2020-10-24 19:04:44 18128 [Note] InnoDB: Using CPU crc32 instructions
2020-10-24 19:04:44 18128 [Note] InnoDB: Initializing buffer pool, size = 384.0M
InnoDB: mmap(412090368 bytes) failed; errno 12
2020-10-24 19:04:44 18128 [ERROR] InnoDB: Cannot allocate memory for the buffer pool
2020-10-24 19:04:44 18128 [ERROR] Plugin 'InnoDB' init function returned error.
2020-10-24 19:04:44 18128 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2020-10-24 19:04:44 18128 [ERROR] Unknown/unsupported storage engine: InnoDB
2020-10-24 19:04:44 18128 [ERROR] Aborting
2020-10-24 19:04:44 18128 [Note] Binlog end
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'partition'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_SYS_DATAFILES'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_SYS_TABLESPACES'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_SYS_FOREIGN_COLS'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_SYS_FOREIGN'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_SYS_FIELDS'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_SYS_COLUMNS'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_SYS_INDEXES'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_SYS_TABLESTATS'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_SYS_TABLES'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_FT_INDEX_TABLE'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_FT_INDEX_CACHE'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_FT_CONFIG'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_FT_BEING_DELETED'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_FT_DELETED'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_FT_DEFAULT_STOPWORD'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_METRICS'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_BUFFER_POOL_STATS'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_BUFFER_PAGE_LRU'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_BUFFER_PAGE'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_CMP_PER_INDEX_RESET'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_CMP_PER_INDEX'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_CMPMEM_RESET'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_CMPMEM'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_CMP_RESET'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_CMP'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_LOCK_WAITS'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_LOCKS'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'INNODB_TRX'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'ARCHIVE'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'PERFORMANCE_SCHEMA'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'BLACKHOLE'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'MyISAM'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'MRG_MYISAM'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'CSV'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'MEMORY'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'sha256_password'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'mysql_old_password'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'mysql_native_password'
2020-10-24 19:04:44 18128 [Note] Shutting down plugin 'binlog'
2020-10-24 19:04:44 18128 [Note] /www/server/mysql/bin/mysqld: Shutdown complete
2020-10-24 20:58:37 25732 [Note] Plugin 'FEDERATED' is disabled.
2020-10-24 20:58:37 25732 [Note] InnoDB: Using atomics to ref count buffer pool pages
2020-10-24 20:58:37 25732 [Note] InnoDB: The InnoDB memory heap is disabled
2020-10-24 20:58:37 25732 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2020-10-24 20:58:37 25732 [Note] InnoDB: Memory barrier is not used
2020-10-24 20:58:37 25732 [Note] InnoDB: Compressed tables use zlib 1.2.11
2020-10-24 20:58:37 25732 [Note] InnoDB: Using Linux native AIO
2020-10-24 20:58:37 25732 [Note] InnoDB: Using CPU crc32 instructions
2020-10-24 20:58:37 25732 [Note] InnoDB: Initializing buffer pool, size = 384.0M
2020-10-24 20:58:37 25732 [Note] InnoDB: Completed initialization of buffer pool
2020-10-24 20:58:37 25732 [Note] InnoDB: Highest supported file format is Barracuda.
2020-10-24 20:58:37 25732 [Note] InnoDB: The log sequence numbers 596318639 and 596318639 in ibdata files do not match the log sequence number 618084329 in the ib_logfiles!
2020-10-24 20:58:37 25732 [Note] InnoDB: Database was not shutdown normally!
2020-10-24 20:58:37 25732 [Note] InnoDB: Starting crash recovery.
2020-10-24 20:58:37 25732 [Note] InnoDB: Reading tablespace information from the .ibd files...
2020-10-24 20:58:37 25732 [Note] InnoDB: Restoring possible half-written data pages
2020-10-24 20:58:37 25732 [Note] InnoDB: from the doublewrite buffer...
InnoDB: Last MySQL binlog file position 0 11046821, file name mysql-bin.000026
2020-10-24 20:58:37 25732 [Note] InnoDB: 128 rollback segment(s) are active.
2020-10-24 20:58:37 25732 [Note] InnoDB: Waiting for purge to start
2020-10-24 20:58:37 25732 [Note] InnoDB: 5.6.49 started; log sequence number 618084329
2020-10-24 20:58:37 25732 [Note] Recovering after a crash using mysql-bin
2020-10-24 20:58:37 25732 [Note] Starting crash recovery...
2020-10-24 20:58:37 25732 [Note] Crash recovery finished.
2020-10-24 20:58:37 25732 [Note] RSA private key file not found: /www/server/data//private_key.pem. Some authentication plugins will not work.
2020-10-24 20:58:37 25732 [Note] RSA public key file not found: /www/server/data//public_key.pem. Some authentication plugins will not work.
2020-10-24 20:58:37 25732 [Note] Server hostname (bind-address): '*'; port: 3306
2020-10-24 20:58:37 25732 [Note] IPv6 is available.
2020-10-24 20:58:37 25732 [Note] - '::' resolves to '::';
2020-10-24 20:58:37 25732 [Note] Server socket created on IP: '::'.
2020-10-24 20:58:37 25732 [Note] Event Scheduler: Loaded 0 events
2020-10-24 20:58:37 25732 [Note] /www/server/mysql/bin/mysqld: ready for connections.
Version: '5.6.49-log' socket: '/tmp/mysql.sock' port: 3306 Source distribution
2020-10-24 23:54:29 25732 [Note] /www/server/mysql/bin/mysqld: Normal shutdown
2020-10-24 23:54:29 25732 [Note] Giving 0 client threads a chance to die gracefully
2020-10-24 23:54:29 25732 [Note] Event Scheduler: Purging the queue. 0 events
Refer to the following article to add SWAP:
Centos7 MySQL 错误 InnoDB: Cannot allocate memory for the buffer pool
Create SWAP file/partition on Linux
Centos7 MySQL 错误 InnoDB: Cannot allocate memory for the buffer pool
Linux view and release swap memory
Linux memory mechanism and manual release of swap and memory
Create, destroy, and use SWAP under Linux (transfer)
Modify the swappiness of the linux swap space to reduce the hard disk cache
How big should the Linux SWAP swap partition be set?
cd /var/
添加SWAP文件快，2GB
dd if=/dev/zero of=swapfile bs=1M count=2048
创建SWAP文件
/sbin/mkswap swapfile
激活SWAP文件
/sbin/swapon swapfile
出现：swapon: swapfile: insecure permissions 0644, 0600 suggested.
把swap设置成644或600权限。
chmod 600 swapfile
提示swapon: /mnt/swap Device or resource busy
需要先关闭之前的swap分区，再重新分配，关闭命令：
swapoff -a
查看SWAP信息是否正确
swapon -s
[root@iZwz96gkli5z588poe7umpZ ~]# swapon -s
Filename Type Size Used Priority
/var/swapfile file 2097148 0 -2
free -m 或者 spapon -s
free -m|grep Swap|awk '{print $3}'
返回0代表未开启（绝大多数），有数代表已开启
添加到fstab文件
echo "/var/swapfile swap swap defaults 0 0" >>/etc/fstab
完事了，free -h 可查看内存和swap情况。