如何诊断cursor pin s wait on x 系列二

如何分析诊断收集信息

1.       查看AWR 报告中high paring 和high version部分内容

 

具体查看这几个部分的内容：'SQLordered by Parse Calls' or 'SQL ordered by Version Count'

 

 

SQL ordered by Parse Calls 关于这部分中的sql 解析执行是否过高，或者能否减小来。

SQL ordered by Version Count关于这部分中的high version sql ，需要找出为啥他们不能共享，可以通过 v$sql_shared_cursor  视图查找原因

 

2.    systemstats 和errorstack 的关注点

对于systemstats 和errorstack 时效性非常重要。需要在问题发生时刻进行dump ，否则过时采集的信息是无效的。在一个高速运行的系统中，那些holders and waiter 进程转瞬即逝。

 

 

根据AWR 的 load profile 部分内容可以初步判断出 系统 sql 解析情况：

如果看到hard parses 很多，表明系统可能没有使用绑定变量，或者有新的sql 上线。

 

对于high version counts  也会导致 cursor:ping S wait on X

使用V$SQL_SHARED_CURSOR可以查找出 sql 不能共享的原因

有些bug可能会导致 high version counts：

Document 1057392.8 Bug 10157392 - High version counts forSQL with binds (BIND_MISMATCH)
Document 9689310.8 Bug 9689310 - Excessive child cursors /high VERSION_COUNT / OERI:17059 due to bind mismatch

 

 

Bug 可能会导致 cursor pin s wait on x :

NB	Bug	Fixed	Description
5650841	Hang / deadlock from ANALYZE of cluster index
16191248	12.1.0.1.1, 12.1.0.2, 12.2.0.0	Hang from concurrent drop of on-commit materialized views or using DBMS_REDEFINITION
14295250	11.2.0.4, 12.1.0.1	Long parse time for large query with many nested views due to much time in epxression analysis code
14191508	11.2.0.3.8, 11.2.0.3.BP16, 11.2.0.4, 12.1.0.1	Slow row cache load due to SEG$ and INDSUBPART$ queries
14176247	11.2.0.4, 12.1.0.1	Many child cursors using Adaptive Cursor Sharing with binds (due to BIND_EQUIV_FAILURE)
18292893	12.1.0.2, 12.2.0.0	Jobs don't execute per schedule with a large number of PDBs
18018515	12.2.0.0	High CPU in qctHasFakeBind (can cause 'cursor: pin S wait on X' waits)
16448569	11.2.0.4, 12.1.0.2, 12.2.0.0	PQ hang/deadlock possible - "cursor: pin S wait on X" waits
16400122	12.2.0.0	Spikes in library cache mutex contention for SQL using SQL Plan Baseline
15850031	11.2.0.4, 12.2.0.0	Rare instance hang: deadlock between 'row cache lock' and 'cursor: pin S wait for X'
14469756	12.2.0.0	Partition pruning causes delay in TBL$OR$IDX$PART$NUM
14302813	11.2.0.4, 12.2.0.0	QC blocked / parse hang for parallel DML executed from remote stored procedure
14029891	11.2.0.4, 12.1.0.1	mutex deadlock having SQL baselines on recursive dictionary cursor
11927619	11.2.0.1.BP11, 11.2.0.2.BP07, 11.2.0.3, 12.1.0.1	DBMS_STATS slow on interval composite partitions
11855965	11.2.0.3, 12.1.0.1	Truncate partition takes long time doing recursive delete on MLOG$
10213073	11.2.0.2.8, 11.2.0.2.BP18, 11.2.0.3, 12.1.0.1	CREATE SYNONYM and CREATE PACKAGE may incorrectly invalidate objects
10171273	11.2.0.2.8, 11.2.0.2.BP08, 11.2.0.3, 12.1.0.1	Long parse time with non-equi subpartitioning under interval partitioning
9944129	11.2.0.1.BP12, 11.2.0.2, 12.1.0.1	SQL not shared due to INST_DRTLD_MISMATCH with global transaction
9935787	11.2.0.3, 12.1.0.1	Long parse time for large inlists - can cause 'cursor: pin S wait on X' waits
9694101	10.2.0.5.7, 11.2.0.2, 12.1.0.1	Hang / deadlock between "cursor: pin S wait on X" and "library cache lock" involving dictionary objects
9499302	10.2.0.5.5, 11.1.0.7.7, 11.2.0.1.BP08, 11.2.0.2, 12.1.0.1	Improve concurrent mutex request handling
9472669	11.2.0.1.BP12, 11.2.0.2, 12.1.0.1	'cursor: pin S wait on X' waits for invalid SQL over DB link
8508078	11.2.0.2, 12.1.0.1	Contention from many concurrent bad SQLs - superseded
12432089	11.2.0.3	library cache lock/cursor: pin S wait on X with parallel partition stats gathering
8441239	11.2.0.1	Library cache lock waits if long running TRUNCATE in progress
8348464	11.1.0.7.2, 11.2.0.1	CREATE SYNONYM and CREATE PACKAGE may incorrectly invalidate objects
7234778	11.2.0.1	Unnecessary "cursor: pin S wait on X" waits
5485914	10.2.0.4	Mutex self deadlock on explain / trace of remote mapped SQL
6143420	10.2.0.5, 11.1.0.6	Deadlock involving "ROW CACHE LOCK" on dc_users AND "CURSOR: PIN S WAIT ON X"
6011045	10.2.0.5.5	DBMS_STATS causes deadlock between 'cursor: pin S wait on X' and 'library cache lock'
7462072	10.2.0.4.3, 10.2.0.5	Unnecessary "cursor: pin S wait on X" waits
5983020	10.2.0.4	MMON deadlock with user session executing ALTER USER
7226463	10.2.0.5	EXECUTE IMMEDIATE no releasing mutex or library cache pin
+	5907779	10.2.0.4	Self deadlock hang on "cursor: pin S wait on X" (typically from DBMS_STATS)