Checkpoint duration and TXNS Blocked
Celso Freitas de Andrade saw checkpoints now taking 1 to 2 seconds, with a few transactions blocked, and asked what to check. Paul Watson asked for onstat -g ckp output, noting average block time was 0.000. Art Kagel and Mike Walker said the delays were negligible and probably not a problem; Mike suggested confirming the real time and trigger. No further reply.
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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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#Informix
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
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 ------------------------------ Art S. Kagel, President and Principal Consultant ASK Database Management Corp. www.askdbmgt.com ------------------------------
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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