CXPACKET
HIGH Top Consumer
#parallelism#cpu#skew
Related diagnostic scripts:
Overview
Occurs when waiting for parallel query execution to complete. Caused by skewed parallelism, exchange buffers filling up, or uneven row distribution across threads. The most commonly observed high-signal wait type.
Key Metrics
| Metric | Description |
|---|---|
| Wait Type | CXPACKET |
| Category | Top Consumer |
| Severity | HIGH |
Troubleshooting
1. Identify the source
Use the following query to identify the top queries contributing to CXPACKET waits:
SELECT TOP 10
[Wait Type] = wait_type,
[Wait Seconds] = wait_time_ms / 1000,
[Wait Count] = waiting_tasks_count,
[Avg Wait Ms] = wait_time_ms / NULLIF(waiting_tasks_count, 0)
FROM sys.dm_os_wait_stats
WHERE wait_type = 'CXPACKET'
ORDER BY wait_time_ms DESC;2. Related diagnostics
- Review overall wait statistics using
sys.dm_os_wait_stats - Check session-level waits via
sys.dm_exec_session_wait_stats - Correlate with
sys.dm_exec_requestsfor blocking analysis