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I haven't seen the SLEEP_TASK wait type before, and today I seem to be getting a ton of them.

I'm not the official DBA, just a SQL Server developer who knows some DBA stuff. We upgraded our servers last weekend to 10.52.2500.0 - R2SP1 I think.

All the info I could find online indicates that SLEEP_TASK means the server is waiting on some sort of internal process to complete. I don't have any blocking or any background processes like checkpoints or ghost cleanup running, so I'm a bit stumped.

Has anyone seen this wait type before, and if so can you give me an idea of what is causing it?

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Extended events might help you see more into what is going on. – Shawn Melton Jan 27 '12 at 21:54

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up vote 23 down vote accepted

SLEEP_TASK is a general wait, used for all sorts of things where a more specific wait type doesn't exist, but it does crop up with hashing operations (join/aggregate) that spill to tempdb, and occasionally at an exchange (Parallelism operator) where a consumer is waiting on something that isn't a normal CXPACKET or EXECSYNC wait. I would check for Hash spills first.

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i have been observing this on an IO capped AWS server doing a sort on a large insert, with an index present; other sumultanios operations are reporting PAGEIOLATCH, but for some reason the insert is SLEEP_TASK – Andrew Hill Oct 21 at 4:11

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