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pt_%x mutex

  • 1.  pt_%x mutex

    Posted 30 days ago
    Consider this excerpt from an onstat -g lmx output...
    Locked mutexes:
    mid addr name holder lkcnt waiter waittime
    -824449722 10509f7f9b8 pt_40efa1 1592045984 0
    Does anybody know what the hex number after the pt_ in the mutex name relates to? I have not been able to find this detail in any manuals. 

    I found this on the old IIUG forum site...

    "pt__ are locks on the partition. Normally that means that threads are expanding a tablespace."

    ...but I want to be able to identify the object that is at the root of the mutex contention. My understanding is that mutex lock contention happens when session threads are trying to initialise the same structure in memory that is already being referenced by another session and thus are put to sleep.

    Any assistance would be appreciated.

    Platform...

    Linux  *******  2.6.32-754.17.1.el6.x86_64 #1 SMP Thu Jun 20 11:47:12 EDT 2019 x86_64 x86_64 x86_64 GNU/Linux

    IBM Informix Dynamic Server Version 11.70.FC7XOB4 -- On-Line -- Up 219 days 13:12:30 -- 799279104 Kbytes





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    Kirit Rana
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  • 2.  RE: pt_%x mutex

    Posted 30 days ago

    Kirit:

    It should be the partnum of the partition being locked. Converting the hex to decimal yields partnum = 4255649.

    Art



    ------------------------------
    Art S. Kagel, President and Principal Consultant
    ASK Database Management Corp.
    www.askdbmgt.com
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  • 3.  RE: pt_%x mutex

    Posted 30 days ago

    Pt_* is the partition mutex, lots of them are not documented as the full name is dynamic. However most are <2char>_<number>. You can normally guess from the 2 char

     

    Convert the numeric part from to hex to decimal and use that to find the table. You might get lucky and oncheck –pT will work

     

    Cheers

    Paul

     






  • 4.  RE: pt_%x mutex

    Posted 30 days ago
    Excellent. Got it. Now I can identify the table or index I suspect is the root of the contention and take the investigation further.

    Thanks Paul and Art.

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    Kirit Rana
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