Sql-server – SLEEP_TASK Wait Type in SQL Server – What does it indicate

I don't believe it is documented anywhere (even in Bob Ward's Wait Type Repository - a useful resource in any case), and I suspect you are quite right about the underlying cause.

If this wait type seems to be causing you significant performance issues (and you've isolated the wait as the cause and not a symptom, by observing relieved pressure when you temporarily disable the trace), probably the best thing would be to investigate the trace and make sure:

• you are filtering adequately to prevent the writing of data you'll never look at.
• you are capturing only the event types you need.
• you aren't writing to a severely under-powered or over-utilized disk, to the same local disks where your data/log files are, or over a network connection that is just not capable of handling the load (if writing remotely the wait may not show up as network - especially if the write is going over iSCSI or other remote-disks-that-look-kind-of-local-to-SQL-Server).

For most things your trace is probably collecting, you may be better off converting your trace to use Extended Events. Not everything there is more lightweight than trace, but most of it is. The EE team at Microsoft blogged about how to do this, but if you're planning a migration to SQL Server 2012, you'll want to watch Jonathan Kehayias' blog.

I believe this issue was fixed in SQL Server 2008 R2 SP2 Cumulative Update #1 (10.50.4260):

KB #2511963 - FIX: Query stops responding in SQL Server 2008 or in SQL Server 2008 R2 if the query alters or stops an Extended Events session

They don't mention your specific wait type but I have seen others who have and stated that this fix resolved their issue. So, if you are literally on SP2 with no CU (10.50.4000), you should consider at least that CU, or a later one (the most recent CU for 2008 R2 SP2 is CU7 (10.50.4286)).