allocateInGen(): increase alloc_blocks (#2747)

[ghc-hetmet.git] / rts / Schedule.c

diff --git a/rts/Schedule.c b/rts/Schedule.c
index 8ab964d..ca6e426 100644 (file)
--- a/rts/Schedule.c
+++ b/rts/Schedule.c
@@ -714,7 +714,8 @@ scheduleYield (Capability **pcap, Task *task)
     Capability *cap = *pcap;
 
     // if we have work, and we don't need to give up the Capability, continue.
-    if (!emptyRunQueue(cap) && !shouldYieldCapability(cap,task))
+    if (!shouldYieldCapability(cap,task) && 
+        (!emptyRunQueue(cap) || blackholes_need_checking))
         return;
 
     // otherwise yield (sleep), and keep yielding if necessary.
@@ -934,8 +935,13 @@ scheduleCheckBlackHoles (Capability *cap)
     {
        ACQUIRE_LOCK(&sched_mutex);
        if ( blackholes_need_checking ) {
-           checkBlackHoles(cap);
            blackholes_need_checking = rtsFalse;
+            // important that we reset the flag *before* checking the
+            // blackhole queue, otherwise we could get deadlock.  This
+            // happens as follows: we wake up a thread that
+            // immediately runs on another Capability, blocks on a
+            // blackhole, and then we reset the blackholes_need_checking flag.
+           checkBlackHoles(cap);
        }
        RELEASE_LOCK(&sched_mutex);
     }