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library cache lock和cursor: pin S wait on X等待

原创 Oracle 作者：531968912 时间：2016-04-27 09:17:52 0 删除 编辑

　1.现象:

客户10.2.0.4 RAC环境，出现大量的library cache lock和cursor: pin S wait on X等待，经分析是由于统计信息收集僵死导致的。
数据库在8点到9点期间，数据库两个节点都存在明显的cursor: pin S wait on X和library cache lock的等待：

　　TOP 5 EVENT:

Event

Waits

Time(s)

Avg   Wait(ms)

%   Total Call Time

Wait   Class

cursor:   pin S wait on X

1,573,056

30,651

19

146.2

Concurrency

library   cache lock

31,757

7,009

221

33.4

Concurrency

CPU   time

 

6,416

 

30.6

 

DFS   lock handle

12,381

2,979

241

14.2

Other

latch:   library cache

1,646

1,974

1,199

9.4

Concurrency

Event

Waits

Time(s)

Avg   Wait(ms)

%   Total Call Time

Wait   Class

cursor:   pin S wait on X

17,586,451

342,437

19

812.1

Concurrency

library   cache lock

63,657

30,153

474

71.5

Concurrency

CPU   time

 

3,820

 

9.1

 

db   file sequential read

241,761

1,094

5

2.6

User   I/O

inactive   session

 

两个节点的等待现象基本一致，而节点1上还存在明显的DFS lock handle等待事件。
通过分析ASH信息，发现library cache lock和cursor: pin S wait on X等待基本上都是6点之后才开始出现：

 2.分析原因 


SELECT trunc(sample_time, 'hh24') TIME, COUNT(*) FROM WRH$_ACTIVE_SESSION_HISTORY ash, wrh$_event_name en WHERE ash.event_id = en.event_id AND sample_time>= to_timestamp('20130703', 'yyyymmdd') AND event_name IN ('cursor: pin S wait on X', 'library cache lock') GROUP BY trunc(sample_time, 'hh24') ORDER BY 1;

 

而观察出现cursor: pin S wait on X和library cache lock等待会话的BLOCKING SESSION，发现大部分处于等待的会话被会话37锁定： 


SELECT to_char(sample_time, 'hh24:mi:ss.ff') TIME, session_id sid, 
decode(en.event_name, 'cursor: pin S wait on X', to_number(substr(ltrim(to_char(p2, '0xxxxxxxxxxxxxxx')), 1, 8), 'xxxxxxxx'), blocking_session) b_sid, 
en.event_name FROM WRH$_ACTIVE_SESSION_HISTORY ash, wrh$_event_name en WHERE ash.event_id = en.event_id(+) AND instance_number = 1 AND sample_time >= to_timestamp('201407140800', 'yyyymmddhh24mi') AND sample_time <= to_timestamp('201407140801', 'yyyymmddhh24mi') ORDER BY 1;

TIME                      SID      B_SID EVENT_NAME
------------------ ---------- ---------- ------------------------------
08:00:09.569              457 4294967291 latch: library cache
08:00:09.569               52        981 cursor: pin S wait ON X
08:00:09.569              168         73 library cache LOCK
08:00:09.569             1763 4294967291 SQL*Net message FROM client
08:00:09.569              123 4294967295 kksfbc child completion
08:00:09.569              476 4294967291 kst: async disk IO
08:00:09.569              500 4294967292 db file sequential READ
08:00:09.569              327 4294967291 SQL*Net message TO client
08:00:09.569              233 4294967291 db file scattered READ
08:00:09.569               73         73 DFS LOCK handle
08:00:09.569             1889 4294967291 gc CURRENT block 2-way
08:00:09.569             1969        981 cursor: pin S wait ON X
08:00:09.569              857        981 cursor: pin S wait ON X
08:00:09.569              812        168 cursor: pin S wait ON X
08:00:09.569              981         73 library cache LOCK
08:00:19.669               52        981 cursor: pin S wait ON X
08:00:19.669              812        168 cursor: pin S wait ON X
08:00:19.669              857        981 cursor: pin S wait ON X
08:00:19.669             1969        981 cursor: pin S wait ON X
08:00:19.669              233 4294967291 db file scattered READ
08:00:19.669              500 4294967292 db file sequential READ
08:00:19.669             1763 4294967291 db file sequential READ
08:00:19.669              476 4294967291 kst: async disk IO
08:00:19.669              457 4294967291 kksfbc child completion
08:00:19.669               73         73 DFS LOCK handle
08:00:19.669              654 4294967291 SQL*Net message TO client
08:00:19.669              168         73 library cache LOCK
08:00:19.669              981         73 library cache LOCK
08:00:29.769             1969        981 cursor: pin S wait ON X
08:00:29.769               52        981 cursor: pin S wait ON X
08:00:29.769              457 4294967291 kksfbc child completion
08:00:29.769              981         73 library cache LOCK
08:00:29.769              168         73 library cache LOCK
08:00:29.769              500 4294967292 db file sequential READ
08:00:29.769               73         73 DFS LOCK handle
08:00:29.769              654 4294967291 SQL*Net message TO client
08:00:29.769              327 4294967291 SQL*Net message TO client
08:00:29.769             1763 4294967291 db file sequential READ
08:00:29.769              857        981 cursor: pin S wait ON X
08:00:29.769              123 4294967295 latch: library cache
08:00:29.769              196 4294967295 latch: library cache
08:00:29.769              233 4294967295 latch: library cache
08:00:29.769              812        168 cursor: pin S wait ON X
08:00:29.769              476 4294967291 kst: async disk IO
08:00:39.879              476 4294967291 kst: async disk IO
08:00:39.879              658 4294967291 db file sequential READ
08:00:39.879              500 4294967292 db file sequential READ
08:00:39.879             1969        981 cursor: pin S wait ON X
08:00:39.879              857        981 cursor: pin S wait ON X
08:00:39.879              812        168 cursor: pin S wait ON X
08:00:39.879               52        981 cursor: pin S wait ON X
08:00:39.879              981         73 library cache LOCK
08:00:39.879              168         73 library cache LOCK
08:00:39.879             1849 4294967291 SQL*Net message TO client
08:00:39.879              327 4294967291 SQL*Net message TO client
08:00:39.879              235 4294967291 rdbms ipc reply
08:00:39.879               19 4294967291 rdbms ipc reply
08:00:39.879               73         73 DFS LOCK handle
08:00:39.879              123 4294967294 enq: WF - contention
08:00:49.987              476 4294967291 kst: async disk IO
08:00:49.987              500 4294967292 db file sequential READ
08:00:49.987              382 4294967291 gc cr block busy
08:00:49.987             1969        981 cursor: pin S wait ON X
08:00:49.987              857        981 cursor: pin S wait ON X
08:00:49.987              812        168 cursor: pin S wait ON X
08:00:49.987              235 4294967295 kksfbc child completion
08:00:49.987              658 4294967295 latch: library cache
08:00:49.987               19 4294967291 latch: library cache
08:00:49.987              981         73 library cache LOCK
08:00:49.987              168         73 library cache LOCK
08:00:49.987             1889 4294967291 SQL*Net message FROM client
08:00:49.987               73         73 DFS LOCK handle
08:00:49.987               52        981 cursor: pin S wait ON X


查询结果

可以判断，导致数据库实例HANG死的原因是因为SID为73的进程： 


SELECT to_char(sample_time, 'hh24:mi:ss'), program, action, event_name FROM wrh$_active_session_history ash, wrh$_event_name en WHERE session_id = 73 AND ash.event_id = en.event_id(+) AND sample_time >= to_date('201307140550', 'yyyymmddhh24mi') AND sample_time <= to_date('201307140601', 'yyyymmddhh24mi') ORDER BY 1;

TO_CHAR( PROGRAM                                  ACTION                         EVENT_NAME
-------- ---------------------------------------- ------------------------------ ---------------------------
05:50:07 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               db file sequential READ
05:50:17 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               db file sequential READ
05:50:27 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:50:37 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:50:47 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               gc cr block 2-way
05:50:57 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:51:08 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:51:18 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               db file scattered READ
05:51:28 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               gc cr multi block request
05:51:38 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               direct path WRITE temp
05:51:48 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:51:58 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:52:08 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:52:18 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               db file scattered READ
05:52:28 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               db file sequential READ
05:52:38 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:52:49 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:52:59 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               db file scattered READ
05:53:09 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:53:19 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               db file scattered READ
05:53:29 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:53:39 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:53:49 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               gc CURRENT GRANT 2-way
05:53:59 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:54:09 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:54:20 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:54:30 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:54:40 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:54:50 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:55:00 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:55:10 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               db file sequential READ
05:55:20 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:55:30 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:55:40 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:55:51 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:56:01 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:56:11 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:56:21 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:56:31 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:56:41 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:56:51 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               gc CURRENT GRANT 2-way
05:57:01 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               library cache pin
05:57:11 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               DFS LOCK handle
05:57:21 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               DFS LOCK handle
05:57:32 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:57:42 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:57:52 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               DFS LOCK handle
05:58:02 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               db file sequential READ
05:58:12 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               db file sequential READ
05:58:22 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:58:32 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:58:42 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:58:52 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:59:03 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:59:13 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:59:23 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:59:33 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
05:59:43 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               db file sequential READ
05:59:53 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
06:00:03 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               DFS LOCK handle
06:00:13 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               latch: library cache
06:00:23 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               DFS LOCK handle
06:00:34 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               DFS LOCK handle
06:00:44 oracle@orcldb5 (J002)                     GATHER_STATS_JOB               DFS LOCK handle
06:00:54 oracle@orcldb5 (J002)                     GATHER_STATS_JOB    


查询结果


		

			

		

	





	　　根据MOS文档，Bug 6011045 – DBMS_STATS causes deadlock between ‘cursor: pin S wait on X’ and ‘library cache lock’ [ID 6011045.8]，这个问题是RAC环境中Oracle收集统计信息的BUG，在自动收集数据字典信息时，可能会出现进程HANG死，并导致大量的library cache lock和cursor: pin S wait on X等待，此外还可能出现DFS lock handle以及row cache lock的等待。

这个BUG确认影响版本包括10.2.0.4和10.2.0.5，这个BUG Oracle在10.2.0.5.5 PSU中进行了修复。


                                                    

                                        

                    
                    

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