SOS_SCHEDULER_YIELD

Overview

Occurs when a task voluntarily yields the scheduler for other tasks to execute. High counts indicate CPU pressure or inefficient query plans that refuse to yield. Normal under healthy CPU load.

Key Metrics

Metric	Description
Wait Type	SOS_SCHEDULER_YIELD
Category	Scheduling
Severity	MEDIUM

Troubleshooting

1. Identify the source

Use the following query to identify the top queries contributing to SOS_SCHEDULER_YIELD 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 = 'SOS_SCHEDULER_YIELD'
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_requests for blocking analysis

See Also

• sys.dm_os_wait_stats (Transact-SQL)
• sys.dm_exec_session_wait_stats (Transact-SQL)
• sys.dm_os_waiting_tasks (Transact-SQL)