high average wait time of wait event "virtual circuit wait”

From: du shenglin <shenglin.du_at_gmail.com>
Date: Thu, 15 Nov 2012 23:13:21 +0800
Message-ID: <CAGpGbogRdnrTe1EwUPLQ5mcK7GZkcdQRhXbJQwY14un6Lyj0sw_at_mail.gmail.com>

Hi all,

   I saw high average wait time of wait event "virtual circuit wait” in my database.

   host: solaris sparc 64bit
   database version: 11g Enterprise Edition Release - 64bit Production

   the database is MTS mode, with 60 dispatcher and 300 shared server. Only less than 10 busy dispatcher and less than 200 active shared server during high wait for "virtual circuit wait”.

   I started to see the high wait event of "virtual circuit wait” after failover to a new node. Sometimes, the average wait time of "virtual circuit wait” was over 25 ms. Normally, it is only about 1ms.

   I saw the high wait of this event with P2=3. Per oracle document, the event '"virtual circuit wait” mean the shared server is blocked waiting on a specific circuit or message, the P2=3 means waiting on a send to the client. Checking the related SQL, most of them were reading some LOB columns.

   I suspected it was related to network issue. however, there is no high wait event and high average wait time of 'sql net more data to client'.

   Do you know what may cause the high average wait time of "virtual circuit wait”? Any comments are welcomed.


Received on Thu Nov 15 2012 - 16:13:21 CET

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