很明显是前面两个mysqld进程导致整体负载较高。
而且，从 Cpu(s) 这行的统计结果也能看的出来，%us 和 %wa 的值较高，表示当前比较大的瓶颈可能是在用户进程消耗的CPU以及磁盘I/O等待上。
我们先分析下磁盘I/O的情况。
执行 sar -d 确认磁盘I/O是否真的较大：
| [yejr@imysql.com:~ ]# sar -d 1 Linux 2.6.32-431.el6.x86_64 (yejr.imysql.com) 01/13/2016 _x86_64_ (24 CPU) 11:54:32 AM dev8-0 5338.00 162784.00 1394.00 30.76 5.24 0.98 0.19 100.00 11:54:33 AM dev8-0 5134.00 148032.00 32365.00 35.14 6.93 1.34 0.19 100.10 11:54:34 AM dev8-0 5233.00 161376.00 996.00 31.03 9.77 1.88 0.19 100.00 11:54:35 AM dev8-0 4566.00 139232.00 1166.00 30.75 5.37 1.18 0.22 100.00 11:54:36 AM dev8-0 4665.00 145920.00 630.00 31.41 5.94 1.27 0.21 100.00 11:54:37 AM dev8-0 4994.00 156544.00 546.00 31.46 7.07 1.42 0.20 100.00 |
再利用 iotop 确认到底哪些进程消耗的磁盘I/O资源最多：
| [yejr@imysql.com:~ ]# iotop Total DISK READ: 60.38 M/s | Total DISK WRITE: 640.34 K/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO> COMMAND 16397 be/4 mysql 8.92 M/s 0.00 B/s 0.00 % 94.77 % mysqld --basedir=/usr/local/m~og_3320/mysql.sock --port=3320 7295 be/4 mysql 10.98 M/s 0.00 B/s 0.00 % 93.59 % mysqld --basedir=/usr/local/m~og_3320/mysql.sock --port=3320 14295 be/4 mysql 10.50 M/s 0.00 B/s 0.00 % 93.57 % mysqld --basedir=/usr/local/m~og_3320/mysql.sock --port=3320 14288 be/4 mysql 14.30 M/s 0.00 B/s 0.00 % 91.86 % mysqld --basedir=/usr/local/m~og_3320/mysql.sock --port=3320 14292 be/4 mysql 14.37 M/s 0.00 B/s 0.00 % 91.23 % mysqld --basedir=/usr/local/m~og_3320/mysql.sock --port=3320 |
可以看到，端口号是3320的实例消耗的磁盘I/O资源比较多，那就看看这个实例里都有什么查询在跑吧。
2. MySQL层面检查确认
首先看下当前都有哪些查询在运行：
| [yejr@imysql.com(db)]> mysqladmin pr|grep -v Sleep +----+----+----------+----+-------+-----+--------------+-----------------------------------------------------------------------------------------------+ | Id |User| Host | db |Command|Time | State | Info | +----+----+----------+----+-------+-----+--------------+-----------------------------------------------------------------------------------------------+ | 25 | x | 10.x:8519 | db | Query | 68 | Sending data | select max(Fvideoid) from (select Fvideoid from t where Fvideoid>404612 order by Fvideoid) t1 | | 26 | x | 10.x:8520 | db | Query | 65 | Sending data | select max(Fvideoid) from (select Fvideoid from t where Fvideoid>484915 order by Fvideoid) t1 | | 28 | x | 10.x:8522 | db | Query | 130 | Sending data | select max(Fvideoid) from (select Fvideoid from t where Fvideoid>404641 order by Fvideoid) t1 | | 27 | x | 10.x:8521 | db | Query | 167 | Sending data | select max(Fvideoid) from (select Fvideoid from t where Fvideoid>324157 order by Fvideoid) t1 | | 36 | x | 10.x:8727 | db | Query | 174 | Sending data | select max(Fvideoid) from (select Fvideoid from t where Fvideoid>324346 order by Fvideoid) t1 | +----+----+----------+----+-------+-----+--------------+-----------------------------------------------------------------------------------------------+ |
