count "dud" sparks (expressions that were already evaluated when sparked)
[ghc.git] / rts / Capability.c
index 2fcd72c..9f7d152 100644 (file)
@@ -219,11 +219,13 @@ initCapability( Capability *cap, nat i )
     initMutex(&cap->lock);
     cap->running_task      = NULL; // indicates cap is free
     cap->spare_workers     = NULL;
+    cap->n_spare_workers   = 0;
     cap->suspended_ccalls  = NULL;
     cap->returning_tasks_hd = NULL;
     cap->returning_tasks_tl = NULL;
     cap->inbox              = (Message*)END_TSO_QUEUE;
     cap->sparks_created     = 0;
+    cap->sparks_dud         = 0;
     cap->sparks_converted   = 0;
     cap->sparks_pruned      = 0;
 #endif
@@ -455,14 +457,33 @@ releaseCapabilityAndQueueWorker (Capability* cap USED_IF_THREADS)
 
     task = cap->running_task;
 
+    // If the Task is stopped, we shouldn't be yielding, we should
+    // be just exiting.
+    ASSERT(!task->stopped);
+
     // If the current task is a worker, save it on the spare_workers
     // list of this Capability.  A worker can mark itself as stopped,
     // in which case it is not replaced on the spare_worker queue.
     // This happens when the system is shutting down (see
     // Schedule.c:workerStart()).
-    if (!isBoundTask(task) && !task->stopped) {
-       task->next = cap->spare_workers;
-       cap->spare_workers = task;
+    if (!isBoundTask(task))
+    {
+        if (cap->n_spare_workers < MAX_SPARE_WORKERS)
+        {
+            task->next = cap->spare_workers;
+            cap->spare_workers = task;
+            cap->n_spare_workers++;
+        }
+        else
+        {
+            debugTrace(DEBUG_sched, "%d spare workers already, exiting",
+                       cap->n_spare_workers);
+            releaseCapability_(cap,rtsFalse);
+            // hold the lock until after workerTaskStop; c.f. scheduleWorker()
+            workerTaskStop(task);
+            RELEASE_LOCK(&cap->lock);
+            shutdownThread();
+        }
     }
     // Bound tasks just float around attached to their TSOs.
 
@@ -619,7 +640,8 @@ yieldCapability (Capability** pCap, Task *task)
                }
                cap->spare_workers = task->next;
                task->next = NULL;
-           }
+                cap->n_spare_workers--;
+            }
            cap->running_task = task;
            RELEASE_LOCK(&cap->lock);
            break;
@@ -708,12 +730,13 @@ shutdownCapability (Capability *cap, Task *task, rtsBool safe)
                 if (!osThreadIsAlive(t->id)) {
                     debugTrace(DEBUG_sched, 
                                "worker thread %p has died unexpectedly", (void *)t->id);
-                        if (!prev) {
-                            cap->spare_workers = t->next;
-                        } else {
-                            prev->next = t->next;
-                        }
-                        prev = t;
+                    cap->n_spare_workers--;
+                    if (!prev) {
+                        cap->spare_workers = t->next;
+                    } else {
+                        prev->next = t->next;
+                    }
+                    prev = t;
                 }
             }
         }