cursor: pin X等待事件

‘cursor: pin * events’等待事件

该类等待事件一般是为了pin相关的子游标

‘cursor: pin X’  当一个进程需要以EXCL X mode获得mutex时， 这类需要EXCL X 模式的串行操作包括:

• 构建一个子游标
• 某个进程已经以X mode持有该Mutex
• 一个或多个进程正在reference 该Mutex (shared mutex pin)

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详见 《深入理解Oracle中的Mutex》一文

Cursor: pin X

•  A session waits on this event when it needs to get a mutex in X mode for serialized operations such as building a cursor.
• When performing exclusive operation on cursor like dbms_shared_pool.purge, keep/unkeep etc.
• Mutex is in the cursor or child cursor.

A session waits on this event when it is requesting an exclusive mutex pin for a cursor object and it must wait because the resource is busy. The mutex pin for a cursor object can be busy either because a session is already holding it exclusive, or there are one or more sessions which are holding shared mutex pin(s). The exclusive waiter must wait until all holders of the pin for that cursor object have released it, before it can be granted.

Solutions

Solutions for mutex wait problems are very similar to each other. See Analysis of Waits on Mutexes for more information and troubleshooting ideas.