MDEV-23224 Windows threadpool - use better threadpool_max_threads default.

vaintroub · vaintroub · commit 5b4e69c05923 · 2024-03-19T11:57:38.000+01:00
Use max_connections in calculation, top prevent possible deadlock, if
max_connection is high.
diff --git a/sql/threadpool_win.cc b/sql/threadpool_win.cc
@@ -355,10 +355,13 @@ int TP_pool_win::init()
   if (IS_SYSVAR_AUTOSIZE(&threadpool_max_threads))
   {
     /*
-     Nr 500 comes from Microsoft documentation,
-     there is no API for GetThreadpoolThreadMaxThreads()
+     Default 500 comes from Microsoft documentation,
+     there is no API for GetThreadpoolThreadMaxThreads().
+
+     To avoid deadlocks, allow at least max_connections + safety
+     margin threads in the pool.
     */
-    SYSVAR_AUTOSIZE(threadpool_max_threads,500);
+    SYSVAR_AUTOSIZE(threadpool_max_threads,std::max(500U,(uint)max_connections + 10));
   }
   else
   {

Original file line number	Diff line number	Diff line change
`@@ -355,10 +355,13 @@ int TP_pool_win::init()`
`355`	`355`	`if (IS_SYSVAR_AUTOSIZE(&threadpool_max_threads))`
`356`	`356`	`{`
`357`	`357`	`/*`
`358`		`- Nr 500 comes from Microsoft documentation,`
`359`		`- there is no API for GetThreadpoolThreadMaxThreads()`
	`358`	`+ Default 500 comes from Microsoft documentation,`
	`359`	`+ there is no API for GetThreadpoolThreadMaxThreads().`
	`360`	`+`
	`361`	`+ To avoid deadlocks, allow at least max_connections + safety`
	`362`	`+ margin threads in the pool.`
`360`	`363`	`*/`
`361`		`- SYSVAR_AUTOSIZE(threadpool_max_threads,500);`
	`364`	`+ SYSVAR_AUTOSIZE(threadpool_max_threads,std::max(500U,(uint)max_connections + 10));`
`362`	`365`	`}`
`363`	`366`	`else`
`364`	`367`	`{`