我认为，MySQL 时不时崩溃的原因是，一个较大的请求超过了 my.cnf 中设置的 innodb-buffer-pool-size（当前为 210M），而我需要首先设置该值才能启动 mysql。
以下是错误日志：
130518 17:28:52 mysqld_safe Number of processes running now: 0
130518 17:28:52 mysqld_safe mysqld restarted
130518 17:28:52 [Note] Plugin 'FEDERATED' is disabled.
130518 17:28:52 InnoDB: Mutexes and rw_locks use GCC atomic builtins
130518 17:28:52 InnoDB: Compressed tables use zlib 1.2.3
130518 17:28:52 InnoDB: Using Linux native AIO
130518 17:28:52 InnoDB: Initializing buffer pool, size = 210.0M
InnoDB: mmap(223117312 bytes) failed; errno 12
130518 17:28:52 InnoDB: Completed initialization of buffer pool
130518 17:28:52 InnoDB: Fatal error: cannot allocate memory for the buffer pool
130518 17:28:52 [ERROR] Plugin 'InnoDB' init function returned error.
130518 17:28:52 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
130518 17:28:52 [ERROR] Unknown/unsupported storage engine: InnoDB
130518 17:28:52 [ERROR] Aborting
130518 17:28:52 [Note] /usr/libexec/mysqld: Shutdown complete
130518 17:28:52 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended
重启服务器并重启mysqld。暂时修复了问题，但是会再次崩溃。
130518 18:22:32 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
130518 18:22:32 [Note] Plugin 'FEDERATED' is disabled.
130518 18:22:32 InnoDB: Mutexes and rw_locks use GCC atomic builtins
130518 18:22:32 InnoDB: Compressed tables use zlib 1.2.3
130518 18:22:32 InnoDB: Using Linux native AIO
130518 18:22:32 InnoDB: Initializing buffer pool, size = 210.0M
130518 18:22:32 InnoDB: Completed initialization of buffer pool
130518 18:22:32 InnoDB: highest supported file format is Barracuda.
InnoDB: The log sequence number in ibdata files does not match
InnoDB: the log sequence number in the ib_logfiles!
130518 18:22:32 InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
InnoDB: Reading tablespace information from the .ibd files...
InnoDB: Restoring possible half-written data pages from the doublewrite
InnoDB: buffer...
130518 18:22:32 InnoDB: Waiting for the background threads to start
130518 18:22:33 InnoDB: 5.5.31 started; log sequence number 789470772
130518 18:22:33 [Note] Server hostname (bind-address): '0.0.0.0'; port: 3306
130518 18:22:33 [Note] - '0.0.0.0' resolves to '0.0.0.0';
[mysqld]
130518 18:22:33 [Note] Server socket created on IP: '0.0.0.0'.
130518 18:22:33 [ERROR] Missing system table mysql.proxies_priv; please run mysql_upgrade to create it
130518 18:22:33 [ERROR] Native table 'performance_schema'.'events_waits_current' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'events_waits_history' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'events_waits_history_long' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'setup_consumers' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'setup_instruments' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'setup_timers' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'performance_timers' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'threads' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'events_waits_summary_by_thread_by_event_name' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'events_waits_summary_by_instance' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'events_waits_summary_global_by_event_name' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'file_summary_by_event_name' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'file_summary_by_instance' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'mutex_instances' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'rwlock_instances' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'cond_instances' has the wrong structure
130518 18:22:33 [ERROR] Native table 'performance_schema'.'file_instances' has the wrong structure
130518 18:22:33 [Note] Event Scheduler: Loaded 0 events
130518 18:22:33 [Note] /usr/libexec/mysqld: ready for connections.
Version: '5.5.31' socket: '/var/lib/mysql/mysql.sock' port: 3306 MySQL Community Server (GPL) by Remi
这是我的 my.cnf：pastebin.com/SSeU8gxK
答案1
添加以下参数并检查问题是否解决：
innodb_buffer_pool_instances=3
innodb_change_buffering=inserts
innodb_flush_method=O_DIRECT