SSMS Internals : What is the meaning of Wait Category in Activity Monitor Under Resource Waits

November 2014
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Posted by blakhani on November 27, 2014

Recently I was working with a friend on performance issue and she asked an simple question.

I use activity monitor tool which is provided with management studio. When I look at the Resource Waits group, there is a column called Wait Category. What does that show and how data is picked? Here is the screenshot from my machine.

At almost same time, same question popped in Facebook group (SQLBangalore) as well. So I decided to dig into more details. Captured the profiler and found that Activity Monitor uses two DMVs to show the values in that section (Resource Waits).

sys.dm_os_wait_stats is used to get information for completed waits
sys.dm_os_waiting_tasks for threads that are in an in-progress wait.

Here are the various waits we could potentially see.

Wait Category	Count(Type)
Backup	7
Buffer I/O	12
Buffer Latch	6
Compilation	3
Full Text Search	3
Idle	26
Latch	9
Lock	21
Logging	5
Memory	6
Network I/O	6
Other	120
Parallelism	3
SQLCLR	17
Transaction	18
User Waits	1

How did I find this? By running profiler! As per profiler, the waits related information in Activity Monitor (AM) is populated by procedure #am_generate_waitstats. This is created when AM is launched. The temporary table which is populated in #am_wait_types which has mapping of “display” values and DMV values.

category_name	wait_type	ignore
Backup	BACKUP	0
Backup	BACKUP_CLIENTLOCK	0
Backup	BACKUP_OPERATOR	0
Backup	BACKUPBUFFER	0
Backup	BACKUPIO	0
Backup	BACKUPTHREAD	0
Backup	DISKIO_SUSPEND	0
Buffer I/O	ASYNC_DISKPOOL_LOCK	0
Buffer I/O	ASYNC_IO_COMPLETION	0
Buffer I/O	FCB_REPLICA_READ	0
Buffer I/O	FCB_REPLICA_WRITE	0
Buffer I/O	IO_COMPLETION	0
Buffer I/O	PAGEIOLATCH_DT	0
Buffer I/O	PAGEIOLATCH_EX	0
Buffer I/O	PAGEIOLATCH_KP	0
Buffer I/O	PAGEIOLATCH_NL	0
Buffer I/O	PAGEIOLATCH_SH	0
Buffer I/O	PAGEIOLATCH_UP	0
Buffer I/O	REPLICA_WRITES	0
Buffer Latch	PAGELATCH_DT	0
Buffer Latch	PAGELATCH_EX	0
Buffer Latch	PAGELATCH_KP	0
Buffer Latch	PAGELATCH_NL	0
Buffer Latch	PAGELATCH_SH	0
Buffer Latch	PAGELATCH_UP	0
Compilation	RESOURCE_SEMAPHORE_MUTEX	0
Compilation	RESOURCE_SEMAPHORE_QUERY_COMPILE	0
Compilation	RESOURCE_SEMAPHORE_SMALL_QUERY	0
Full Text Search	SOAP_READ	0
Full Text Search	SOAP_WRITE	0
Full Text Search	MSSEARCH	0
Idle	ONDEMAND_TASK_QUEUE	1
Idle	REQUEST_FOR_DEADLOCK_SEARCH	1
Idle	RESOURCE_QUEUE	1
Idle	LOGMGR_QUEUE	1
Idle	KSOURCE_WAKEUP	1
Idle	LAZYWRITER_SLEEP	1
Idle	BROKER_RECEIVE_WAITFOR	1
Idle	CHECKPOINT_QUEUE	1
Idle	CHKPT	1
Idle	BROKER_EVENTHANDLER	1
Idle	BROKER_TRANSMITTER	1
Idle	SERVER_IDLE_CHECK	1
Idle	SNI_HTTP_ACCEPT	1
Idle	SLEEP_BPOOL_FLUSH	1
Idle	SLEEP_DBSTARTUP	1
Idle	SLEEP_DCOMSTARTUP	1
Idle	SLEEP_MSDBSTARTUP	1
Idle	SLEEP_SYSTEMTASK	1
Idle	SLEEP_TASK	1
Idle	SLEEP_TEMPDBSTARTUP	1
Idle	SQLTRACE_BUFFER_FLUSH	1
Idle	TRACEWRITE	1
Idle	WAITFOR_TASKSHUTDOWN	1
Idle	WAIT_FOR_RESULTS	1
Idle	XE_DISPATCHER_WAIT	1
Idle	XE_TIMER_EVENT	1
Latch	VIEW_DEFINITION_MUTEX	0
Latch	DEADLOCK_ENUM_MUTEX	0
Latch	LATCH_DT	0
Latch	LATCH_EX	0
Latch	LATCH_KP	0
Latch	LATCH_NL	0
Latch	LATCH_SH	0
Latch	LATCH_UP	0
Latch	INDEX_USAGE_STATS_MUTEX	0
Lock	LCK_M_BU	0
Lock	LCK_M_IS	0
Lock	LCK_M_IU	0
Lock	LCK_M_IX	0
Lock	LCK_M_RIn_NL	0
Lock	LCK_M_RIn_S	0
Lock	LCK_M_RIn_U	0
Lock	LCK_M_RIn_X	0
Lock	LCK_M_RS_S	0
Lock	LCK_M_RS_U	0
Lock	LCK_M_RX_S	0
Lock	LCK_M_RX_U	0
Lock	LCK_M_RX_X	0
Lock	LCK_M_S	0
Lock	LCK_M_SCH_M	0
Lock	LCK_M_SCH_S	0
Lock	LCK_M_SIU	0
Lock	LCK_M_SIX	0
Lock	LCK_M_U	0
Lock	LCK_M_UIX	0
Lock	LCK_M_X	0
Logging	LOGBUFFER	0
Logging	LOGMGR	0
Logging	LOGMGR_FLUSH	0
Logging	LOGMGR_RESERVE_APPEND	0
Logging	WRITELOG	0
Memory	UTIL_PAGE_ALLOC	0
Memory	SOS_RESERVEDMEMBLOCKLIST	0
Memory	SOS_VIRTUALMEMORY_LOW	0
Memory	LOWFAIL_MEMMGR_QUEUE	0
Memory	RESOURCE_SEMAPHORE	0
Memory	CMEMTHREAD	0
Network I/O	ASYNC_NETWORK_IO	0
Network I/O	DBMIRROR_SEND	0
Network I/O	NET_WAITFOR_PACKET	0
Network I/O	OLEDB	0
Network I/O	MSQL_DQ	0
Network I/O	DTC_STATE	0
Other	EXECUTION_PIPE_EVENT_INTERNAL	0
Other	FAILPOINT	0
Other	INTERNAL_TESTING	0
Other	IO_AUDIT_MUTEX	0
Other	KTM_ENLISTMENT	0
Other	KTM_RECOVERY_MANAGER	0
Other	KTM_RECOVERY_RESOLUTION	0
Other	MSQL_SYNC_PIPE	0
Other	MIRROR_SEND_MESSAGE	0
Other	MISCELLANEOUS	0
Other	MSQL_XP	0
Other	REQUEST_DISPENSER_PAUSE	0
Other	PARALLEL_BACKUP_QUEUE	0
Other	PRINT_ROLLBACK_PROGRESS	0
Other	QNMANAGER_ACQUIRE	0
Other	QPJOB_KILL	0
Other	QPJOB_WAITFOR_ABORT	0
Other	QRY_MEM_GRANT_INFO_MUTEX	0
Other	QUERY_ERRHDL_SERVICE_DONE	0
Other	QUERY_EXECUTION_INDEX_SORT_EVENT_OPEN	0
Other	QUERY_NOTIFICATION_MGR_MUTEX	0
Other	QUERY_NOTIFICATION_SUBSCRIPTION_MUTEX	0
Other	QUERY_NOTIFICATION_TABLE_MGR_MUTEX	0
Other	QUERY_NOTIFICATION_UNITTEST_MUTEX	0
Other	QUERY_OPTIMIZER_PRINT_MUTEX	0
Other	QUERY_REMOTE_BRICKS_DONE	0
Other	QUERY_TRACEOUT	0
Other	RECOVER_CHANGEDB	0
Other	REPL_CACHE_ACCESS	0
Other	REPL_SCHEMA_ACCESS	0
Other	DBMIRROR_WORKER_QUEUE	0
Other	DBMIRRORING_CMD	0
Other	DBTABLE	0
Other	DAC_INIT	0
Other	DBCC_COLUMN_TRANSLATION_CACHE	0
Other	DBMIRROR_DBM_EVENT	0
Other	DBMIRROR_DBM_MUTEX	0
Other	DBMIRROR_EVENTS_QUEUE	0
Other	DEADLOCK_TASK_SEARCH	0
Other	DEBUG	0
Other	DISABLE_VERSIONING	0
Other	DLL_LOADING_MUTEX	0
Other	DROPTEMP	0
Other	DUMP_LOG_COORDINATOR	0
Other	DUMP_LOG_COORDINATOR_QUEUE	0
Other	DUMPTRIGGER	0
Other	EC	0
Other	EE_PMOLOCK	0
Other	EE_SPECPROC_MAP_INIT	0
Other	ENABLE_VERSIONING	0
Other	ERROR_REPORTING_MANAGER	0
Other	FSAGENT	1
Other	FT_RESTART_CRAWL	0
Other	FT_RESUME_CRAWL	0
Other	FULLTEXT GATHERER	0
Other	GUARDIAN	0
Other	HTTP_ENDPOINT_COLLCREATE	0
Other	HTTP_ENUMERATION	0
Other	HTTP_START	0
Other	IMP_IMPORT_MUTEX	0
Other	IMPPROV_IOWAIT	0
Other	ABR	0
Other	BROKER_REGISTERALLENDPOINTS	0
Other	BROKER_SHUTDOWN	0
Other	BROKER_TASK_STOP	1
Other	BAD_PAGE_PROCESS	0
Other	BROKER_CONNECTION_RECEIVE_TASK	0
Other	BROKER_ENDPOINT_STATE_MUTEX	0
Other	CURSOR	0
Other	CURSOR_ASYNC	0
Other	BUILTIN_HASHKEY_MUTEX	0
Other	CHECK_PRINT_RECORD	0
Other	BROKER_INIT	0
Other	BROKER_MASTERSTART	0
Other	SOSHOST_EVENT	0
Other	SOSHOST_INTERNAL	0
Other	SOSHOST_MUTEX	0
Other	SOSHOST_RWLOCK	0
Other	SOSHOST_SEMAPHORE	0
Other	SOSHOST_SLEEP	0
Other	SOSHOST_TRACELOCK	0
Other	SOSHOST_WAITFORDONE	0
Other	SOS_STACKSTORE_INIT_MUTEX	0
Other	SOS_SYNC_TASK_ENQUEUE_EVENT	0
Other	SHUTDOWN	0
Other	SOS_CALLBACK_REMOVAL	0
Other	SOS_DISPATCHER_MUTEX	0
Other	SOS_LOCALALLOCATORLIST	0
Other	SOS_OBJECT_STORE_DESTROY_MUTEX	0
Other	SOS_PROCESS_AFFINITY_MUTEX	0
Other	SNI_CRITICAL_SECTION	0
Other	SNI_HTTP_WAITFOR_0_DISCON	0
Other	SNI_LISTENER_ACCESS	0
Other	SNI_TASK_COMPLETION	0
Other	SEC_DROP_TEMP_KEY	0
Other	SEQUENTIAL_GUID	0
Other	VIA_ACCEPT	0
Other	SQLSORT_NORMMUTEX	0
Other	SQLSORT_SORTMUTEX	0
Other	WAITSTAT_MUTEX	0
Other	WCC	0
Other	WORKTBL_DROP	0
Other	XE_BUFFERMGR_ALLPROCECESSED_EVENT	0
Other	XE_BUFFERMGR_FREEBUF_EVENT	0
Other	XE_DISPATCHER_JOIN	0
Other	SQLTRACE_LOCK	0
Other	SQLTRACE_SHUTDOWN	0
Other	SQLTRACE_WAIT_ENTRIES	0
Other	SRVPROC_SHUTDOWN	0
Other	TEMPOBJ	0
Other	THREADPOOL	1
Other	TIMEPRIV_TIMEPERIOD	0
Other	XE_TIMER_MUTEX	0
Other	XE_TIMER_TASK_DONE	0
Other	XE_MODULEMGR_SYNC	0
Other	XE_OLS_LOCK	0
Other	XE_SERVICES_MUTEX	0
Other	XE_SESSION_CREATE_SYNC	0
Other	XE_SESSION_SYNC	0
Other	XE_STM_CREATE	0
Parallelism	CXPACKET	1
Parallelism	EXCHANGE	1
Parallelism	EXECSYNC	1
SQLCLR	CLR_AUTO_EVENT	1
SQLCLR	CLR_CRST	0
SQLCLR	CLR_JOIN	0
SQLCLR	CLR_MANUAL_EVENT	1
SQLCLR	CLR_MEMORY_SPY	0
SQLCLR	CLR_MONITOR	0
SQLCLR	CLR_RWLOCK_READER	0
SQLCLR	CLR_RWLOCK_WRITER	0
SQLCLR	CLR_SEMAPHORE	0
SQLCLR	CLR_TASK_START	0
SQLCLR	CLRHOST_STATE_ACCESS	0
SQLCLR	ASSEMBLY_LOAD	0
SQLCLR	FS_GARBAGE_COLLECTOR_SHUTDOWN	0
SQLCLR	SQLCLR_APPDOMAIN	0
SQLCLR	SQLCLR_ASSEMBLY	0
SQLCLR	SQLCLR_DEADLOCK_DETECTION	0
SQLCLR	SQLCLR_QUANTUM_PUNISHMENT	0
Transaction	TRAN_MARKLATCH_DT	0
Transaction	TRAN_MARKLATCH_EX	0
Transaction	TRAN_MARKLATCH_KP	0
Transaction	TRAN_MARKLATCH_NL	0
Transaction	TRAN_MARKLATCH_SH	0
Transaction	TRAN_MARKLATCH_UP	0
Transaction	TRANSACTION_MUTEX	0
Transaction	XACT_OWN_TRANSACTION	0
Transaction	XACT_RECLAIM_SESSION	0
Transaction	XACTLOCKINFO	0
Transaction	XACTWORKSPACE_MUTEX	0
Transaction	DTC_TMDOWN_REQUEST	0
Transaction	DTC_WAITFOR_OUTCOME	0
Transaction	MSQL_XACT_MGR_MUTEX	0
Transaction	MSQL_XACT_MUTEX	0
Transaction	DTC	0
Transaction	DTC_ABORT_REQUEST	0
Transaction	DTC_RESOLVE	0
User Waits	WAITFOR	1

Hope this helps in understanding Activity monitor wait category little better.

Cheers,

Balmukund Lakhani

Twitter @blakhani

Author: SQL Server 2012 AlwaysOn – Paperback, Kindle

This entry was posted on November 27, 2014 at 3:30 AM and is filed under Internals, SQL Server Management Studio, SSMS. Tagged: Activity Monitor, Internals, Resource Waits, SQL Server Management Studio, ssms, ssms tips, ssms tips and tricks, Wait Category. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

3 Responses to “SSMS Internals : What is the meaning of Wait Category in Activity Monitor Under Resource Waits”

Alister McPherson said

November 27, 2014 at 9:49 AM
I recommend using miniDBA (www.minidba.com) to see real time wait statistics with their descriptions and how they fluctuate over time.

Reply
Aman Ankit said

November 27, 2014 at 6:07 PM
Wonderful stuff sirji. Everytime i had used queries to check wait types, expensive queries etc but didn’t realised we have a good stuff in management studio in a few clicks.

Reply
Aman Ankit said

November 28, 2014 at 12:06 PM
@Alister- Your recommendation is good but minidba is not a free tool.

Reply

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