Re: SQL causing 100% CPU utilization
From: Gerard H. Pille <ghp_at_skynet.be>
Date: Tue, 10 May 2011 19:45:42 +0200
Message-ID: <4dc979c6$0$14259$ba620e4c_at_news.skynet.be>
Steven Holland wrote:
>
> You guys are right. Here's what I found out.
>
> Looking at the AWR report closer I noticed a back ground wait event
> that caught my eye that I missed before. The 'rdbms ipc message'
> metric was too high. The event rdbms ipc message indicates that a
> process is waiting for a message to arrive on his message queue. The
> number of message blocks parameter was set too small. If a process
> needs a message it will get the latch, search a linked list for a free
> message block, unlink this message block , put this message on the
> message queue for the intended process and then release this latch.
> indicated If a process needs a message it will get the latch, search a
> linked list for a free message block, unlink this message block , put
> this message on the message queue for the intended process and then
> release the latch. The event rdbms ipc message indicates that a
> process is waiting for a message to arrive on his message queue. The
> event rdbms ipc message reply is used to indicate that a message is
> expected back by the sending process."
>
> So....The process was pegging the CPU requesting a message block from
> the LRU list in the SGA but ran into latch contention. The latch
> contention also caused contention with the rollback process.
>
>
>
Date: Tue, 10 May 2011 19:45:42 +0200
Message-ID: <4dc979c6$0$14259$ba620e4c_at_news.skynet.be>
Steven Holland wrote:
>
> You guys are right. Here's what I found out.
>
> Looking at the AWR report closer I noticed a back ground wait event
> that caught my eye that I missed before. The 'rdbms ipc message'
> metric was too high. The event rdbms ipc message indicates that a
> process is waiting for a message to arrive on his message queue. The
> number of message blocks parameter was set too small. If a process
> needs a message it will get the latch, search a linked list for a free
> message block, unlink this message block , put this message on the
> message queue for the intended process and then release this latch.
> indicated If a process needs a message it will get the latch, search a
> linked list for a free message block, unlink this message block , put
> this message on the message queue for the intended process and then
> release the latch. The event rdbms ipc message indicates that a
> process is waiting for a message to arrive on his message queue. The
> event rdbms ipc message reply is used to indicate that a message is
> expected back by the sending process."
>
> So....The process was pegging the CPU requesting a message block from
> the LRU list in the SGA but ran into latch contention. The latch
> contention also caused contention with the rollback process.
>
>
>
Steven, you really have to take it easy with acid. You should read your own messages once you're clean, you'll see what I mean. Received on Tue May 10 2011 - 12:45:42 CDT