Make threadpool_stall_limit variable really dynamic

sql/sys_vars.cc

@@ -2211,6 +2211,12 @@ static bool fix_threadpool_size(sys_var*, THD*, enum_var_type)
   tp_set_threadpool_size(threadpool_size);
   return false;
 }
+
+
+static bool fix_threadpool_stall_limit(sys_var*, THD*, enum_var_type)
+{
+  tp_set_threadpool_stall_limit(threadpool_size);
+}
 #endif
 
 #ifdef _WIN32
@@ -2241,12 +2247,14 @@ static Sys_var_uint Sys_threadpool_size(
 );
 static Sys_var_uint Sys_threadpool_stall_limit(
  "thread_pool_stall_limit",
- "Maximum query execution time before in milliseconds,"
+ "Maximum query execution time in milliseconds,"
  "before an executing non-yielding thread is considered stalled."
  "If a worker thread is stalled, additional worker thread "
  "may be created to handle remaining clients.",
   GLOBAL_VAR(threadpool_stall_limit), CMD_LINE(REQUIRED_ARG),
-  VALID_RANGE(60, UINT_MAX), DEFAULT(500), BLOCK_SIZE(1)
+  VALID_RANGE(60, UINT_MAX), DEFAULT(500), BLOCK_SIZE(1),
+  NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), 
+  ON_UPDATE(fix_threadpool_stall_limit)
 );
 #endif /* !WIN32 */
 static Sys_var_uint Sys_threadpool_max_threads(

sql/threadpool.h

@@ -41,6 +41,7 @@ extern TP_STATISTICS tp_stats;
 extern void tp_set_min_threads(uint val);
 extern void tp_set_max_threads(uint val);
 extern int tp_set_threadpool_size(uint val);
+extern void tp_set_threadpool_stall_limit(uint val);
 
 /* Activate threadpool scheduler */
 extern void tp_scheduler(void);

sql/threadpool_unix.cc

@@ -1324,6 +1324,7 @@ bool tp_init()
   DBUG_RETURN(0);
 }
 
+
 void tp_end()
 {
   DBUG_ENTER("tp_end");
@@ -1365,3 +1366,13 @@ int tp_set_threadpool_size(uint size)
   group_count= size;
   return 0;
 }
+
+void tp_set_threadpool_stall_limit(uint limit)
+{
+  if (!started)
+    return;
+  mysql_mutex_lock(&(pool_timer.mutex));
+  pool_timer.tick_interval= limit;
+  mysql_cond_signal(&(pool_timer.cond));
+  mysql_mutex_unlock(&(pool_timer.mutex));
+}