Remove incorrect assertions in steal()

2 files changed, 12 insertions, 3 deletions

diff --git a/rts/Sparks.c b/rts/Sparks.c
index cb3d8d98eb..571529afbb 100644
--- a/rts/Sparks.c
+++ b/rts/Sparks.c
@@ -202,10 +202,12 @@ steal(SparkPool *deque)
   StgClosurePtr stolen;
   StgWord b,t; 
 
-  ASSERT_SPARK_POOL_INVARIANTS(deque); 
+// Can't do this on someone else's spark pool:
+// ASSERT_SPARK_POOL_INVARIANTS(deque); 
 
   b = deque->bottom;
   t = deque->top;
+
   if (b - t <= 0 ) { 
     return NULL; /* already looks empty, abort */
   }
@@ -222,7 +224,9 @@ steal(SparkPool *deque)
       return NULL;
   }  /* else: OK, top has been incremented by the cas call */
 
-  ASSERT_SPARK_POOL_INVARIANTS(deque); 
+// Can't do this on someone else's spark pool:
+// ASSERT_SPARK_POOL_INVARIANTS(deque); 
+
   /* return stolen element */
   return stolen;
 }
diff --git a/rts/Sparks.h b/rts/Sparks.h
index f24ccca4ff..fd62c1288d 100644
--- a/rts/Sparks.h
+++ b/rts/Sparks.h
@@ -52,7 +52,12 @@ typedef struct  SparkPool_ {
 
 
 /* INVARIANTS, in this order: reasonable size,
-   topBound consistent, space pointer, space accessible to us */
+   topBound consistent, space pointer, space accessible to us.
+   
+   NB. This is safe to use only (a) on a spark pool owned by the
+   current thread, or (b) when there's only one thread running, or no
+   stealing going on (e.g. during GC).
+*/
 #define ASSERT_SPARK_POOL_INVARIANTS(p)         \
   ASSERT((p)->size > 0);                        \
   ASSERT((p)->topBound <= (p)->top);            \