oracle wait event virtual circuit status

 

2011-9-21

 下午开发部门反映wms系统反映缓慢

查看系统等待事件

select event,count(1)  from gv$session_wait

group by event

order by count(1) desc;

发现有比较多的virtual circuit status

查询资料发现virtual circuit status idle event

interface. The common idle events are as follows:

Idle Events
client message	PX Deq: Execute Reply
dispatcher timer	PX Deq: Execution Msg
gcs for action	PX Deq: Signal ACK
gcs remote message	PX Deq: Table Q Normal
ges remote message	PX Deque wait
i/o slave wait	PX Idle Wait
jobq slave wait	queue messages
lock manager wait for remote message	rdbms ipc message
null event	slave wait
parallel query dequeue	smon timer
pipe get	SQL*Net message from client
PL/SQL lock timer	SQL*Net message to client
pmon timer	SQL*Net more data from client
PX Deq Credit: need buffer	virtual circuit status
PX Deq Credit: send blkd	wakeup time manager

 

 

 

 

 

 

找到具体的osuser通知他讲卡主的plsql cancel掉之后 就好了

 

问题出现前提条件：
1. 使用 oracle 11gR2
2. 是客户端PL/SQL在连接数据库的时候使用shared server
3. plsql在默认连接的时候是创建多个session的：Session  Mode 选择 Multi session或者Dual session

此时查询 v$session 视图可以看到，session的等待事件就是 virtual circuit wait，注销plsql即可看到等待事件取消

只有条件1,2和条件3同时达到才会产生这个等待事件，如果使用dedicated链接或者plsql配置上选择Single session 都不会产生这个等待事件。


期间参考 metalink 上多篇文档和有人提问的回复：
【参考一】

This is a performance monitoring enhancement to split the 'virtual circuit status' wait event into two new

wait events:

  "shared server idle wait" - for when the shared server is
                              idle waiting for something to do

  "virtual circuit wait"    - for when the shared server is
                              blocked waiting on a specific
                              circuit / message

The wait "virtual circuit status" no longer exist with this fix.

Before the bug fix  the 'virtual circuit status' event was classified as an
 
idle event but was used for both idle and non-idle waits.  Since the idle time
 
dominated the total time for the event, it obscured any true issues with the
 
other waits under the event.

With this bug fix included in 11.1.0.7 and 11.2 The 'virtual circuit status' wait
event was removed and replaced by two new wait events: 'shared server idle wait' and
'virtual circuit wait'.  The wait on the common queue uses 'shared server idle wait' and
all the otherwaits use 'virtual circuit wait'

原文链接：https://support.oracle.com/CSP/main/article?cmd=show&type=COMMUNITIES&doctype=COMTHREAD&id=85058

【参考二】Bug 6653834 - Split "virtual circuit status" into idle / non-idle waits [ID 6653834.8]

This note gives a brief overview of bug 6653834.
The content was last updated on: 11-JAN-2010
Click here for details of each of the sections below.

Affects:

Product (Component)	Oracle Server (Rdbms)
Range of versions believed to be affected	Versions < 11.2
Versions confirmed as being affected	9.2.0.8 10.1.0.5 10.2.0.3 10.2.0.4 11.1.0.6
Platforms affected	Generic (all / most platforms affected)

The fix for this bug introduces a notable change in behaviour thus:
Notable change of behaviour introduced in 11.1.0.7

Fixed:

This issue is fixed in

11.1.0.7 (Server Patch Set) 11.2.0.1 (Base Release)