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Incredible High Waits on Always on Cluster #480

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hvoges opened this issue Jul 19, 2023 · 2 comments
Open

Incredible High Waits on Always on Cluster #480

hvoges opened this issue Jul 19, 2023 · 2 comments

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@hvoges
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hvoges commented Jul 19, 2023

Did you check DOCS to make sure there is no workaround?
https://sqlwatch.io/docs/

Describe the bug
SQLWatch shows incredible High Waits (>20000)

To Reproduce
Steps to reproduce the behavior:
This behaviour shows on an always on Instance with quite a few replicas. The Server has no performance issues. As far as I could reproduce the results, it seems the wait-query does not exclude the Default HADR-Wait-Types, especially HADR_WorkQueue and HADR_NOTIFICATION_DEQUEUE. According to sys_dm_os_wait_stats, these are expected waits:
HADR_Work_Queue: This is an expected wait when there are ready workers waiting for new work, which is the normal state
HADR_NOTIFICATION_DEQUE: A background task that processes Windows Server Failover Clustering notifications is waiting for the next notification. Internal use only.
When I exclude these two, the result of the query in usp_sqlwatch_logger_requests_and_sessions.sql drops from >20000 to ~500, but there may be more exptected Waiting-tasks that can be excluded.

Expected behavior
These Events should be included in dbo.sqlwatch_config_exclude_wait_stats.

Screenshots
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Windows Server (please complete the following information):

  • OS Version: Windows Server 2016

SQL Server (please complete the following information):

  • SQL Version: SQL-Server 2017
  • SQL Edition: Enterprise

SQL Server Management Studio (SSMS -> about -> copy info):

  • paste "about" info here: 14.0.17289.0

SQLWATCH version (from DACPAC or from sysinstances)

  • 4.8.0.548

Additional context
Add any other context about the problem here.

@marcingminski
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Thanks, this doesn’t sound like an issue as such, just a matter of adding the wait exclusion, which is configurable. For others to benefit from your findings, are you able to submit this as a PR?

Thanks

@hvoges
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hvoges commented Jul 19, 2023

Yeah, sure, I can do that.

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