StgClosure *
findSpark (Capability *cap)
{
- /* use the normal Sparks.h interface (internally modified to enable
- concurrent stealing)
- and immediately turn the spark into a thread when successful
- */
Capability *robbed;
StgClosurePtr spark;
rtsBool retry;
nat i = 0;
+ if (!emptyRunQueue(cap)) {
+ // If there are other threads, don't try to run any new
+ // sparks: sparks might be speculative, we don't want to take
+ // resources away from the main computation.
+ return 0;
+ }
+
// first try to get a spark from our own pool.
// We should be using reclaimSpark(), because it works without
// needing any atomic instructions: