threadpool : Make throttling interval depend on thread_pool_stall_limitbb-10.2-snow-threadpool

A thread_pool_stall_limit which is smaller than default would result
in quicker creation of threads.

3 files changed, 14 insertions, 11 deletions

diff --git a/sql/sys_vars.cc b/sql/sys_vars.cc
index 2a793646c7f..fe0cfdf6d6e 100644
--- a/sql/sys_vars.cc
+++ b/sql/sys_vars.cc
@@ -3414,7 +3414,7 @@ static Sys_var_uint Sys_threadpool_stall_limit(
  "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(10, UINT_MAX), DEFAULT(500), BLOCK_SIZE(1),
+  VALID_RANGE(1, UINT_MAX), DEFAULT(DEFAULT_THREADPOOL_STALL_LIMIT), BLOCK_SIZE(1),
   NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), 
   ON_UPDATE(fix_threadpool_stall_limit)
 );
diff --git a/sql/threadpool.h b/sql/threadpool.h
index ba17dc042c2..561c4f3e086 100644
--- a/sql/threadpool.h
+++ b/sql/threadpool.h
@@ -20,7 +20,7 @@ extern uint threadpool_min_threads;  /* Minimum threads in pool */
 extern uint threadpool_idle_timeout; /* Shutdown idle worker threads  after this timeout */
 extern uint threadpool_size; /* Number of parallel executing threads */
 extern uint threadpool_max_size;
-extern uint threadpool_stall_limit;  /* time interval in 10 ms units for stall checks*/
+extern uint threadpool_stall_limit;  /* time interval in milliseconds for stall checks*/
 extern uint threadpool_max_threads;  /* Maximum threads in pool */
 extern uint threadpool_oversubscribe;  /* Maximum active threads in group */
 extern uint threadpool_prio_kickup_timer;  /* Time before low prio item gets prio boost */
@@ -30,6 +30,7 @@ extern uint threadpool_mode; /* Thread pool implementation , windows or generic
 #define TP_MODE_GENERIC 1
 #endif
 
+#define DEFAULT_THREADPOOL_STALL_LIMIT 500U
 
 struct TP_connection;
 extern void tp_callback(TP_connection *c);
diff --git a/sql/threadpool_generic.cc b/sql/threadpool_generic.cc
index 400d072df3c..e630b5b5782 100644
--- a/sql/threadpool_generic.cc
+++ b/sql/threadpool_generic.cc
@@ -19,6 +19,7 @@
 #include <sql_class.h>
 #include <my_pthread.h>
 #include <scheduler.h>
+#include <algorithm> /* std::max*/
 
 #ifdef HAVE_POOL_OF_THREADS
 
@@ -984,23 +985,24 @@ end:
  
  The actual values were not calculated using any scientific methods.
  They just look right, and behave well in practice.
- 
- TODO: Should throttling depend on thread_pool_stall_limit?
 */
+
+#define THROTTLING_FACTOR (threadpool_stall_limit/std::max(DEFAULT_THREADPOOL_STALL_LIMIT,threadpool_stall_limit))
+
 static ulonglong microsecond_throttling_interval(thread_group_t *thread_group)
 {
   int count= thread_group->thread_count;
   
-  if (count < 4)
+  if (count < 1+ (int)threadpool_oversubscribe)
     return 0;
-  
+
   if (count < 8)
-    return 50*1000; 
-  
+    return 50*1000*THROTTLING_FACTOR;
+
   if(count < 16)
-    return 100*1000;
-  
-  return 200*1000;
+    return 100*1000*THROTTLING_FACTOR;
+
+  return 200*100*THROTTLING_FACTOR;
 }