Merge pull request #3509 from BrentOzarULTD/3491_sp_BlitzFirst_max_worker_threads

#3491 sp_BlitzFirst max worker threads

Author: BrentOzar

Documentation/sp_BlitzFirst_Checks_by_Priority.md

@@ -6,8 +6,8 @@ Before adding a new check, make sure to add a Github issue for it first, and hav
 
 If you want to change anything about a check - the priority, finding, URL, or ID - open a Github issue first. The relevant scripts have to be updated too.
 
-CURRENT HIGH CHECKID: 47
-If you want to add a new check, start at 48
+CURRENT HIGH CHECKID: 49
+If you want to add a new check, start at 50.
 
 | Priority | FindingsGroup | Finding | URL | CheckID |
 |----------|---------------------------------|---------------------------------------|-------------------------------------------------|----------|
@@ -47,6 +47,7 @@ If you want to add a new check, start at 48
 | 100 | Query Problems | Skewed Parallelism | https://www.brentozar.com/go/skewedup | 43 |
 | 100 | Query Problems | Query with a memory grant exceeding @MemoryGrantThresholdPct | https://www.brentozar.com/memory-grants-sql-servers-public-toilet/ | 46 |
 | 200 | Wait Stats | (One per wait type) | https://www.brentozar.com/sql/wait-stats/#(waittype) | 6 |
+| 210 | Potential Upcoming Problems | High Number of Connections |https://www.brentozar.com/archive/2014/05/connections-slow-sql-server-threadpool/ | 49 |
 | 210 | Query Stats | Plan Cache Analysis Skipped | https://www.brentozar.com/go/topqueries | 18 |
 | 210 | Query Stats | Top Resource-Intensive Queries | https://www.brentozar.com/go/topqueries | 17 |
 | 250 | Server Info | Batch Requests per Second | https://www.brentozar.com/go/measure | 19 |
@@ -57,3 +58,4 @@ If you want to add a new check, start at 48
 | 251 | Server Info | Database Count |  | 22 |
 | 251 | Server Info | Database Size, Total GB |  | 21 |
 | 251 | Server Info | Memory Grant/Workspace info |  | 40 |
+| 254 | Informational | Thread Time Inaccurate |  | 48 |

sp_BlitzFirst.sql

@@ -143,7 +143,9 @@ DECLARE @StringToExecute NVARCHAR(MAX),
 	@dm_exec_query_statistics_xml BIT = 0,
 	@total_cpu_usage BIT = 0,
 	@get_thread_time_ms NVARCHAR(MAX) = N'',
-	@thread_time_ms FLOAT = 0;
+	@thread_time_ms FLOAT = 0,
+	@logical_processors INT = 0,
+	@max_worker_threads INT = 0;
 
 /* Sanitize our inputs */
 SELECT
@@ -308,6 +310,10 @@ BEGIN
                 @FinishSampleTimeWaitFor = DATEADD(ss, @Seconds, GETDATE());
 
 
+	SELECT @logical_processors = COUNT(*)
+		FROM sys.dm_os_schedulers
+		WHERE status = 'VISIBLE ONLINE';
+
     IF EXISTS
 	   (
 
@@ -2581,6 +2587,35 @@ If one of them is a lead blocker, consider killing that query.'' AS HowToStopit,
 
 	END
 
+    /* Potential Upcoming Problems - High Number of Connections - CheckID 49 */
+	IF (@Debug = 1)
+	BEGIN
+		RAISERROR('Running CheckID 49',10,1) WITH NOWAIT;
+	END
+	IF CAST(SERVERPROPERTY('edition') AS VARCHAR(100)) LIKE '%64%' AND SERVERPROPERTY('EngineEdition') <> 5
+		BEGIN
+		IF @logical_processors <= 4
+			SET @max_worker_threads = 512;
+		ELSE IF @logical_processors > 64 AND 
+			((@v = 13 AND @build >= 5026) OR @v >= 14)
+			SET @max_worker_threads = 512 + ((@logical_processors - 4) * 32)
+		ELSE
+			SET @max_worker_threads = 512 + ((@logical_processors - 4) * 16)
+
+		IF @max_worker_threads > 0
+			BEGIN
+				INSERT INTO #BlitzFirstResults (CheckID, Priority, FindingsGroup, Finding, URL, Details)
+				SELECT 49 AS CheckID,
+					210 AS Priority,
+					'Potential Upcoming Problems' AS FindingGroup,
+					'High Number of Connections' AS Finding,
+					'https://www.brentozar.com/archive/2014/05/connections-slow-sql-server-threadpool/' AS URL,
+					'There are ' + CAST(SUM(1) AS VARCHAR(20)) + ' open connections, which would lead to ' + @LineFeed + 'worker thread exhaustion and THREADPOOL waits' + @LineFeed + 'if they all ran queries at the same time.' AS Details
+			FROM sys.dm_exec_connections c
+			HAVING SUM(1) > @max_worker_threads;
+			END
+		END
+
 	RAISERROR('Finished running investigatory queries',10,1) WITH NOWAIT;