I am experiencing instances where not all the cores are being utilize for certain queries in SQL Server 2012.
When this happens one of the cores becomes max to 100% CPU usage. This causes everything on the server to slow down and no one else can use the sql server until the offending query is kill from the server. My guess is that it is related to parallelism.
Any suggestions on how to go about debugging this? I can't see the actual execution plan because we always end up killing the offending query. It is a production machine so I can't really play around with it.