| Event Id | 8650 |
| Source | MSSQLServer |
| Description | Intra-query parallelism caused your server command (process ID #%d) to deadlock. Rerun the query without intra-query parallelism by using the query hint option (maxdop 1). |
| Event Information | According to Microsoft Cause: On a multiprocessor computer, SQL Server determines at execution time if the current system workload and configuration information allow for parallel query execution for a query that could benefit from a parallel plan. SQL Server re-examines the optimal number of thread decisions each time a query execution plan is retrieved from the procedure cache. For example, one execution of a query can result in use of a serial plan, a later execution of the same query can result in a parallel plan using three threads, and a third execution can result in a parallel plan using four threads. You may see the above error if one or more of the threads used by the parallel query deadlocks on another thread within the same query. Since the number of threads used at each execution can vary, and the entire plan can change with a change in data or statistics, you may not see the error every time you execute the query. For more information about parallelism, see "Deadlocks Involving Parallelism" and "Degree of Parallelism" in Books Online and Microsoft Knowledge Base article 837983. Resolution: Follow these steps: 1.Resubmit the query. A later execution may not encounter this error. If the error is received by an application, configure the application to retry one or more times when this error is encountered. For instance, from a SQL Server job, such as a replication job, you can configure the job step to retry when this error is encountered. 2.Force the query to only use one CPU by either setting the max degree of parallelism option server-wide with sp_configure, or use the OPTION (MAXDOP 1) query hint for this particular query. For more information about setting configuration options, see "Setting Configuration Options" in Books Online. For more information about query hints, see the "OPTION clause" section of "SELECT" in Books Online. 3.Rewrite the query to reduce the chance that it will deadlock on itself. 4.General performance tuning such as re-evaluating indexes or executing UPDATE STATISTICS can reduce the amount of time each thread needs to execute which reduces the chance of a deadlock occurring. |
| Reference Links | Event Id:8650 of Source Id:MSSQLServer |
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