SSAS Config: Increasing Query Concurrency RRS feed

  • Question

  • Currently stress testing a server and trying to increase the "Processing pool busy I/O job threads". While simulating a load of 50 concurrent queries, "Processing pool busy I/O job threads" is pegged at 20 and the "Processing pool I/O job queue length" is anywhere from 40-160 jobs.

    I've been tweaking the following properties:

    • ThreadPool \ Process \ MaxThreads (Default 0, Current -4)
    • ThreadPool \ Query \ MaxThreads (Default 0, Current -4)
    • etc

    ...and since I'm trying to simulate a highly concurrent system, I've also changed the following properties:

    • CoordinatorQueryBalancingFactor (Default -1, Current 1)
    • CoordinatorQueryBoostPriorityLevel (Default 3, Current 0)

    ...but I can't seem to get the "Processing pool busy I/O job threads" above 20. When I look in the msmdsrv log, I see the following:

    Are the highlighted parts ("and a concurrency of 20") ...

    • hard wired to the number of physical cores?
    • related to the "Processing pool busy I/O job threads"?

    How can I make the concurrency of the "Processing pool busy I/O job threads" counter go up? I've been all over the interwebs for this including the SSAS-ops/perf guide and am stumped at this point.  

    Virtual Server Specs:

    • 20 physical cores (40 logical)
    • 128 GB memory
    • 2 NUMA nodes

    Update: after a bit of reading (SQL Server 2008 Analysis Services Unleashed), I found what appears to be a reference to this "concurrency"...

    "...because by default each thread requires 1MB of memory for the stack, the system must allocate 0.5GB of memory to support 512 threads. Fortunately, this will not happen because Analysis Services limits the number of active threads by value of the "Concurrency" property."

    1. Is this "Concurrency" property the 20 I'm seeing in the msmdsrv log file (highlighted above)? 
    2. Is it the [IOProcess\Concurrency], [Query\Concurrency], [Process\Concurrency] properties in the msmdsrv.ini config file? The ones that default to "2" and are "An advanced property that you should not change, except under the guidance of Microsoft support" according to documentation (here) ?

    Update2: after more reading (on I/O completion ports), I think this is something for which I need to engage the storage admins to get confirmation on the network config between the actual server and disks. 

    BI Developer and lover of data (Blog | Twitter)

    • Edited by BillAnton Tuesday, September 30, 2014 2:51 PM
    Monday, September 29, 2014 10:48 PM

All replies

  • Hi Bill,

    Thank you for your question. 

    I am trying to involve someone more familiar with this topic for a further look at this issue. Sometime delay might be expected from the job transferring. Your patience is greatly appreciated. 

    Thank you for your understanding and support.


    Charlie Liao
    TechNet Community Support

    Tuesday, September 30, 2014 7:55 AM
  • Hi Bill,

    From a support perspective this is really beyond what we can do here in the forums. If you cannot determine your answer here or on your own, consider opening a support case with us. Visit this link to see the various support options that are available to better meet your needs:  http://support.microsoft.com/default.aspx?id=fh;en-us;offerprophone.



    Wednesday, October 22, 2014 2:12 AM