Re: PX Deq Credit: send blkd

From: Riyaj Shamsudeen <>
Date: Fri, 29 Aug 2008 10:10:48 -0500
Message-ID: <>

  As you correctly pointed out, PX slaved are blocked.   One obvious reason I can think is smaller large pool. What is your large pool size set to ? Do you use ASMM - Automatic Shared memory management stuff? If yes, do you see any growth or shrink for large pool ? If large pool is not configured, it is possible that shared pool fragmentation to cause PX slaves to wait for these PX events. v$sgastat is a good place to start.

   What other events do you in statspack report or AWR report during that time frame?

Riyaj Shamsudeen
The Pythian Group
Personal :

Martin Klier wrote:
> Hi list,
> I've got massive wait events named "PX Deq Credit: send blkd". As far as
> I know, that's a parallel query issue, a producer is faster then the
> consumer. But thats a textbook explanantion I simply don't understand.
> The obvious option, to increase PARALLEL_EXECUTION_MESSAGE_SIZE, does
> not fit since it's set to the (x86_64) architecture's maximum, 64k.
> The system is rather capable, and CPU load is less than 30%, disk IO
> around 100MB/s, the underlying ASM diskgroups have been successfully
> tested with nearly 1GB/s.
> The query in question is a huge MERGE statement with APPEND PARALLEL
> hints, a little abstracted form here:


Received on Fri Aug 29 2008 - 10:10:48 CDT

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