Data Driven Subscriptions Error - the query processor could not start the necessary thread resources for parallel query execution

Question

Hi,
We are getting the following error when certain data driven subscriptions are fired off: "the query processor could not start the necessary thread resources for parallel query execution".  I've read other posts that have the same error, and
the solution usually involves adjusting MaxDOP to limit the number of queries that are fired off in parallel.  
Unfortunately, we cannot change this setting on our server for performance reasons (outside of data driven subscriptions, it negatively impacts our ETL processing times).  We tried putting query hints like "OPTION (MAXDOP 2);" in the reports
that are causing the error, but it did not resolve the problem.
Are there any settings within Reporting Services that can be adjusted to limit the number of subscriptions that get fired off in parallel?
Any help is appreciated - thanks!

Answer 1

Yes, that is correct.  It's a painful problem, because you don't know which specific subscription failed. For example, we have a data driven subscription that sends out about 800 emails. Lately, we've been having a handful of them fail. You don't know
which ones out of the 800 failed though, even from the RS log files - all it tells you is that "the
query processor could not start the necessary thread resources for parallel query execution".
Thanks, I'll try changing <MaxQueueThreads> and will let you know if it works.
On a side note: I've noticed that it is only reports with cascading parameters (ex. where parameter 2 is dependent on the selection from parameter 1) that get this error message...