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Does DPA blockers view show ALL blockers or just the ones that block for at least 1s ?

Hi,

Does DPA blockers view show ALL blockers or just the ones that block for at least 1s ? I have application logs that lead me to believe there must be some blocking going on but I don't see that in the blockers view.

Even in other situations with blockers listed, I have never seen any shown with less than 1s blocking time. None of the would be blockers took more a second to complete.

We are on SQL Server 2012.

Thanks,

Karthik

  • Karthik, we poll or sample once every second.  When we do that, we assign 1 second of blocking even if the block actually only took 10 ms.  It's just that we "caught" it when it was actively blocking another SPID.  Hope that helps explain why you see 1 second or in increments of even seconds.

  • Thanks for the quick response.

    Just to confirm my understanding.

    1) Only those SPIDS that are blocking others at the moment you sampled would show up as blockers. And they are deemed to have been blocking for the duration of the sampling interval.

    2) The SPIDs that blocked completely inside a sampling interval would be missed. eg. A SPID that started blocking 10ms after the last sampling and stopped blocking 10ms before the current sampling would not be caught.

    Is this correct ?

  • Correct - great explanation (better than mine!)  8 )