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Unable to get session latch.

  • 1.  Unable to get session latch.

    Posted 23 days ago
    Hi.

    I'm running on 14.10.FC3 / Linux.

    Just saw a few occurrences of these in online.log:

    10/08/20 16:45:22 Performance Advisory: Unable to get session latch.
    10/08/20 16:45:22   Results: This can happen during high connectivity periods where sessions are allocated and freed frequently.
    10/08/20 16:45:22   Action: This can impact session and tenant limits processing and low memory manager processing.
    10/08/20 16:45:34 Performance Advisory: Unable to get session latch.
    10/08/20 16:45:34   Results: This can happen during high connectivity periods where sessions are allocated and freed frequently.
    10/08/20 16:45:34   Action: This can impact session and tenant limits processing and low memory manager processing.

    Any ideas what I can do to prevent this? The engine is running happily in spite of this.

    Thanks in advance,
    -Snorri

    ------------------------------
    Snorri Bergmann
    ------------------------------


  • 2.  RE: Unable to get session latch.

    Posted 23 days ago
    Snorri:

    This is usually caused by Java apps that do not use persistent connections. Fix the apps and the problem goes away!

    Art

    Art S. Kagel, President and Principal Consultant
    ASK Database Management


    Disclaimer: Please keep in mind that my own opinions are my own opinions and do not reflect on the IIUG, nor any other organization with which I am associated either explicitly, implicitly, or by inference.  Neither do those opinions reflect those of other individuals affiliated with any entity with which I am affiliated nor those of the entities themselves.








  • 3.  RE: Unable to get session latch.

    Posted 23 days ago
    Thanks Art.

    We  do not have any Java apps connecting. However, it's possible we have apps that connect very frequently. Is that the main cause? 

    Regards,
    -S

    ------------------------------
    Snorri Bergmann
    ------------------------------



  • 4.  RE: Unable to get session latch.

    Posted 23 days ago
    It can be, and it can be aggravated by frequent queries on sysscblst SMI table (or syssessions view built on top of that).

    ------------------------------
    Andreas Legner
    ------------------------------



  • 5.  RE: Unable to get session latch.

    Posted 23 days ago
    Yes, Snorri. Java apps are notorious for this, but other apps, especially those designed by folk who trained on SQL Server (SQL Server connect/disconnect is particularly cheap since most are local connections). that connect and disconnect frequently.

    Art

    Art S. Kagel, President and Principal Consultant
    ASK Database Management


    Disclaimer: Please keep in mind that my own opinions are my own opinions and do not reflect on the IIUG, nor any other organization with which I am associated either explicitly, implicitly, or by inference.  Neither do those opinions reflect those of other individuals affiliated with any entity with which I am affiliated nor those of the entities themselves.