A SQL Server wait type that occurs when threads in a parallel query execution plan are waiting for other threads to complete before exchanging data.
- CX_PACKET waits are normal in parallel query execution: They represent synchronization overhead between parallel worker threads.
- Excessive CX_PACKET waits may indicate: Suboptimal parallelism configuration, MAXDOP settings that are too high, or skewed data causing uneven work distribution across threads.
- DBAs investigate CX_PACKET waits alongside CXCONSUMER waits: Introduced in SQL Server 2016 SP2+, CXCONSUMER waits help differentiate producer/consumer thread imbalances.
- Tuning strategies include: Adjusting MAXDOP at the server, database, or query level; reviewing Cost Threshold for Parallelism settings; and analyzing query plans for data skew.
- CX_PACKET is one of the most commonly misinterpreted wait types: Moderate levels are expected and do not indicate a problem in parallel workloads.
- Related terms: Parallelism, MAXDOP, Wait Statistics, Execution Plan, Resource Governor.
