Get a breakdown of waiting tasks and sessions binding

task-session-stats.sql

SELECT
		task_state
	,	SUM(CASE WHEN session_id IS NULL THEN 0 ELSE 1 END) AS tasks_session_bound
	,	SUM(CASE WHEN session_id IS NULL THEN 1 ELSE 0 END) AS tasks_session_unbound
	,	COUNT(*) AS total_tasks
FROM	sys.dm_os_tasks
GROUP BY
		task_state