i have cloud vps server, cpu 512 mb.
i have website. if i hold f5 in browser after 10-20 sec mysql server no responding and it gives me error
SQLSTATE[HY000]  Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
i also installed drupal, open home page and hold f5, it also crashes mysql.
after that mysql server need to restart
service mysqld restart
i think problem is in mysql server configuration.
server centos 6
log file after f5 hold
160502 10:42:45 mysqld_safe Number of processes running now: 0 160502 10:42:45 mysqld_safe mysqld restarted 160502 10:42:45 [Note] /usr/libexec/mysqld (mysqld 5.5.48) starting as process 12843 ... 160502 10:42:45 [Note] Plugin 'FEDERATED' is disabled. 160502 10:42:45 InnoDB: The InnoDB memory heap is disabled 160502 10:42:45 InnoDB: Mutexes and rw_locks use GCC atomic builtins 160502 10:42:45 InnoDB: Compressed tables use zlib 1.2.3 160502 10:42:45 InnoDB: Using Linux native AIO 160502 10:42:45 InnoDB: Initializing buffer pool, size = 128.0M InnoDB: mmap(137363456 bytes) failed; errno 12 160502 10:42:45 InnoDB: Completed initialization of buffer pool 160502 10:42:45 InnoDB: Fatal error: cannot allocate memory for the buffer pool 160502 10:42:45 [ERROR] Plugin 'InnoDB' init function returned error. 160502 10:42:45 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed. 160502 10:42:45 [ERROR] Unknown/unsupported storage engine: InnoDB 160502 10:42:45 [ERROR] Aborting 160502 10:42:45 [Note] /usr/libexec/mysqld: Shutdown complete 160502 10:42:45 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended