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Checkpoint duration and TXNS Blocked

  • 1.  Checkpoint duration and TXNS Blocked

    Posted 19 days ago
    ​Hello everyone,

    We are having problems with one of our servers. For a few days now, checkpoints that generally lasted 0 seconds are repeatedly taking 1 second, sometimes 2 seconds, and some transactions are being blocked.

    "21:11:18  Checkpoint Completed:  duration was 1 seconds.
    21:11:18  Tue Mar 30 - loguniq 11739, logpos 0x407bc018, timestamp: 0xf7909df3 Interval: 60010

    21:11:18  Maximum server connections 758
    21:11:18  Checkpoint Statistics - Avg. Txn Block Time 0.000, # Txns blocked 2, Plog used 106074, Llog used 91900

    21:15:38  Logical Log 11739 Complete, timestamp: 0xf7be866a.
    21:16:20  Checkpoint Completed:  duration was 1 seconds.
    21:16:20  Tue Mar 30 - loguniq 11740, logpos 0xb1d018, timestamp: 0xf7c17899 Interval: 60011

    21:16:20  Maximum server connections 758
    21:16:20  Checkpoint Statistics - Avg. Txn Block Time 0.000, # Txns blocked 4, Plog used 61346, Llog used 66431

    21:16:41  Logical Log 11739 - Backup Started
    21:18:25  Logical Log 11739 - Backup Completed
    21:21:21  Checkpoint Completed:  duration was 1 seconds.
    21:21:21  Tue Mar 30 - loguniq 11740, logpos 0x19814b54, timestamp: 0xf8029771 Interval: 60012

    21:21:21  Maximum server connections 758
    21:21:21  Checkpoint Statistics - Avg. Txn Block Time 0.000, # Txns blocked 0, Plog used 98401, Llog used 101644

    21:26:22  Checkpoint Completed:  duration was 1 seconds.
    21:26:22  Tue Mar 30 - loguniq 11740, logpos 0x321ac018, timestamp: 0xf852b6a1 Interval: 60013

    21:26:22  Maximum server connections 758
    21:26:22  Checkpoint Statistics - Avg. Txn Block Time 0.000, # Txns blocked 1, Plog used 138177, Llog used 100795"

    Any ideas what to check first to try to solve this problem?

    Thanks!

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    Celso Freitas
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  • 2.  RE: Checkpoint duration and TXNS Blocked

    Posted 19 days ago

    What is onstat –g ckp showing ?

     

    How long would you like the transactions to be blocked for 'cos at the moment is 0.000 seconds J

     

    Cheers

    Paul

     

     

     






  • 3.  RE: Checkpoint duration and TXNS Blocked

    Posted 19 days ago
    Celso:

    Honestly, is anyone besides you noticing these delays of less than 1/1000th second affecting a handful of sessions every five minutes or so? I personally doubt it. Think of it this way, there are 86,400 seconds in a day, if some process were running for 24 hours and every single checkpoint for the day blocks this one session every time for as much as 1/1000th second, that's 120 checkpoints total which will delay processing of the process for 1.2seconds versus all checkpoints not blocking. 

    I think you are looking for a solution to a problem you don't have.

    Art

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    Art S. Kagel, President and Principal Consultant
    ASK Database Management Corp.
    www.askdbmgt.com
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  • 4.  RE: Checkpoint duration and TXNS Blocked

    Posted 19 days ago
    As the others have said, probably not a big deal...but need to see onstat -g ckp to confirm the actual checkpoint time (times in the log are rounded), plus the checkpoint trigger (most likely CKPTINTVL looking at the timings in the log).  The Avg Block Time is still zero, which is not a lot!  Are you simply doing more changes recently?

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    Mike Walker
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