MySQL 5.6因为OOM导致数据库重启

线上的一套MySQL 5.6的从库，因为OOM而导致数据库重启。

# tail -50 /var/log/messagesNov 13 16:00:40 app-push-db2 kernel: Out of memory: Kill process 26121 (mysqld) score 957 or sacrifice childNov 13 16:00:40 app-push-db2 kernel: Killed process 26121 (mysqld) total-vm:18804176kB, anon-rss:15541596kB, file-rss:0kB, shmem-rss:0kB

报错原因：

这台实例所在的服务器上面部署了单实例MySQL，物理内存为16G，分配给数据库的缓存innodb_fuffer_pool_size为12G。

# free -g              total        used        free      shared  buff/cache   availableMem:             15          10           0           0           5           4Swap:             0           0           0

为了提高性能，这台实例关闭了磁盘的swap交换。

# cat /etc/rc.local#!/bin/bash# THIS FILE IS ADDED FOR COMPATIBILITY PURPOSES## It is highly advisable to create own systemd services or udev rules# to run scripts during boot instead of using this file.## In contrast to previous versions due to parallel execution during boot# this script will NOT be run after all other services.## Please note that you must run 'chmod +x /etc/rc.d/rc.local' to ensure# that this script will be executed during boot.touch /var/lock/subsys/localswapoff -a

当客户端连接多的时候，导致内存资源耗尽。

解决方法：

将innodb_buffer_pool_size调整为10G，预留出一些内存给操作系统和客户端连接。

重启数据库，使参数生效。

# grep innodb_buffer_pool /etc/my.cnfinnodb_buffer_pool_size=10G