count "dud" sparks (expressions that were already evaluated when sparked)
[ghc.git] / rts / Capability.c
index 5f54eca..9f7d152 100644 (file)
@@ -62,9 +62,8 @@ Capability * rts_unsafeGetMyCapability (void)
 STATIC_INLINE rtsBool
 globalWorkToDo (void)
 {
-    return blackholes_need_checking
-       || sched_state >= SCHED_INTERRUPTING
-       ;
+    return sched_state >= SCHED_INTERRUPTING
+        || recent_activity == ACTIVITY_INACTIVE; // need to check for deadlock
 }
 #endif
 
@@ -220,11 +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
@@ -456,14 +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.
 
@@ -620,7 +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;
@@ -637,43 +658,6 @@ yieldCapability (Capability** pCap, Task *task)
 }
 
 /* ----------------------------------------------------------------------------
- * Wake up a thread on a Capability.
- *
- * This is used when the current Task is running on a Capability and
- * wishes to wake up a thread on a different Capability.
- * ------------------------------------------------------------------------- */
-
-void
-wakeupThreadOnCapability (Capability *cap,
-                          Capability *other_cap, 
-                          StgTSO *tso)
-{
-    MessageWakeup *msg;
-
-    // ASSUMES: cap->lock is held (asserted in wakeupThreadOnCapability)
-    if (tso->bound) {
-       ASSERT(tso->bound->task->cap == tso->cap);
-       tso->bound->task->cap = other_cap;
-    }
-    tso->cap = other_cap;
-
-    ASSERT(tso->why_blocked != BlockedOnMsgWakeup || 
-           tso->block_info.closure->header.info == &stg_IND_info);
-
-    ASSERT(tso->block_info.closure->header.info != &stg_MSG_WAKEUP_info);
-
-    msg = (MessageWakeup*) allocate(cap, sizeofW(MessageWakeup));
-    msg->header.info = &stg_MSG_WAKEUP_info;
-    msg->tso = tso;
-    tso->block_info.closure = (StgClosure *)msg;
-    dirty_TSO(cap, tso);
-    write_barrier();
-    tso->why_blocked = BlockedOnMsgWakeup;
-
-    sendMessage(other_cap, (Message*)msg);
-}
-
-/* ----------------------------------------------------------------------------
  * prodCapability
  *
  * If a Capability is currently idle, wake up a Task on it.  Used to 
@@ -746,12 +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;
                 }
             }
         }
@@ -857,7 +842,7 @@ freeCapabilities (void)
 
 void
 markSomeCapabilities (evac_fn evac, void *user, nat i0, nat delta, 
-                      rtsBool prune_sparks USED_IF_THREADS)
+                      rtsBool no_mark_sparks USED_IF_THREADS)
 {
     nat i;
     Capability *cap;
@@ -881,9 +866,7 @@ markSomeCapabilities (evac_fn evac, void *user, nat i0, nat delta,
        }
 
 #if defined(THREADED_RTS)
-        if (prune_sparks) {
-            pruneSparkQueue (evac, user, cap);
-        } else {
+        if (!no_mark_sparks) {
             traverseSparkQueue (evac, user, cap);
         }
 #endif
@@ -906,24 +889,3 @@ markCapabilities (evac_fn evac, void *user)
    Messages
    -------------------------------------------------------------------------- */
 
-#ifdef THREADED_RTS
-
-void sendMessage(Capability *cap, Message *msg)
-{
-    ACQUIRE_LOCK(&cap->lock);
-
-    msg->link = cap->inbox;
-    cap->inbox = msg;
-
-    if (cap->running_task == NULL) {
-       cap->running_task = myTask(); 
-            // precond for releaseCapability_()
-       releaseCapability_(cap,rtsFalse);
-    } else {
-        contextSwitchCapability(cap);
-    }
-
-    RELEASE_LOCK(&cap->lock);
-}
-
-#endif // THREADED_RTS