抓 TOP SQL 解决CPU利用率过高问题

--模拟CPU利用率过高的情况：

SQL> select count(*) from  T_LTE_CARD_INFO ;

COUNT(*)

----------

3516598

SQL> select * from  T_LTE_CARD_INFO ;

[[email protected] ~]$ top

top - 11:10:20 up 19:31,  3 users,  load average: 0.17, 0.23, 0.14

Tasks: 187 total,   3 running, 184 sleeping,   0 stopped,   0 zombie

Cpu(s): 15.7%us,  8.2%sy,  0.0%ni, 74.3%id,  1.1%wa,  0.0%hi,  0.7%si,  0.0%st

Mem:   3925464k total,  3774424k used,   151040k free,    64040k buffers

Swap:  8388600k total,   366612k used,  8021988k free,  1963848k cached

PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND

7085 oracle    20   0 45480  10m 7388 R 56.7  0.3   0:13.21 sqlplus

6525 root      20   0 98.4m 4460 3164 R 31.2  0.1   2:50.75 sshd

22 root      20   0     0    0    0 S  4.3  0.0   0:30.05 events/3

2954 oracle    20   0 1687m 125m 120m S  2.7  3.3   0:04.18 oracle

19 root      20   0     0    0    0 S  1.0  0.0   0:06.06 events/0

21 root      20   0     0    0    0 S  0.3  0.0   0:03.63 events/2

2349 mysql     20   0 1121m 247m  696 S  0.3  6.5   1:01.55 mysqld

2952 oracle    20   0 1686m  46m  42m S  0.3  1.2   0:18.78 oracle

2958 oracle    20   0 1688m  53m  47m S  0.3  1.4   0:18.12 oracle

--查找后台在干什么

[[email protected] ~]$ ps -ef | grep 7085

oracle    7085  6764 29 11:08 pts/0    00:00:55 sqlplus

oracle    7089  7085  0 11:08 ?        00:00:00 oracleorcl (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq)))

oracle    7101  6950  0 11:11 pts/1    00:00:00 grep 7085

[[email protected] ~]$

--找到具体的SQL语句，原来是在执行大表查询

[[email protected] ~]$ sqlplus " /as sysdba"

SQL>

SQL> SELECT b.sql_text

2    FROM v$session a, v$sqlarea b

3   WHERE     a.sql_hash_value = b.hash_value

4         AND a.sid = (SELECT A.SID

5                        FROM V$SESSION A, V$PROCESS P

6                       WHERE P.ADDR = A.PADDR AND P.SPID = 7089)

7  ;

SQL_TEXT

--------------------------------------------------------------------------------

select * from  T_LTE_CARD_INFO

SQL> SELECT a.pid,

2         a.spid,

3         b.sid,

4         b.serial#,

5         c.sql_text

6    FROM v$process a, v$session b, v$sqlarea c

7   WHERE a.addr = b.paddr AND b.sql_address = c.address AND B.PROCESS=‘7085‘

8  ;

PID SPID                SID    SERIAL#   SQL_TEXT

--------------------------------------------------------------------------------

16 7089                144       3293    select * from  T_LTE_CARD_INFO

SQL> alter system kill session ‘144,3293‘;

System altered.

--CPU利用率下降

[email protected] ~]$ top

top - 11:17:26 up 19:38,  3 users,  load average: 0.29, 0.31, 0.20

Tasks: 187 total,   1 running, 186 sleeping,   0 stopped,   0 zombie

Cpu(s):  0.4%us,  0.2%sy,  0.0%ni, 98.7%id,  0.8%wa,  0.0%hi,  0.0%si,  0.0%st

Mem:   3925464k total,  3746036k used,   179428k free,    58188k buffers

Swap:  8388600k total,   367056k used,  8021544k free,  1941180k cached

PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND

1 root      20   0 19364  612  436 S  0.0  0.0   0:01.69 init

2 root      20   0     0    0    0 S  0.0  0.0   0:00.00 kthreadd

3 root      RT   0     0    0    0 S  0.0  0.0   0:00.01 migration/0

4 root      20   0     0    0    0 S  0.0  0.0   0:00.12 ksoftirqd/0

5 root      RT   0     0    0    0 S  0.0  0.0   0:00.00 migration/0

6 root      RT   0     0    0    0 S  0.0  0.0   0:00.12 watchdog/0

7 root      RT   0     0    0    0 S  0.0  0.0   0:00.03 migration/1

8 root      RT   0     0    0    0 S  0.0  0.0   0:00.00 migration/1

9 root      20   0     0    0    0 S  0.0  0.0   0:00.45 ksoftirqd/1

10 root      RT   0     0    0    0 S  0.0  0.0   0:00.11 watchdog/1

11 root      RT   0     0    0    0 S  0.0  0.0   0:00.01 migration/2

来自为知笔记(Wiz)