diff options
| -rw-r--r-- | rts/GC.c | 44 |
1 files changed, 34 insertions, 10 deletions
@@ -172,6 +172,7 @@ static void zero_static_object_list ( StgClosure* first_static ); static rtsBool traverse_weak_ptr_list ( void ); static void mark_weak_ptr_list ( StgWeak **list ); +static rtsBool traverse_blackhole_queue ( void ); static StgClosure * eval_thunk_selector ( nat field, StgSelector * p ); @@ -723,6 +724,11 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) } } + // if any blackholes are alive, make the threads that wait on + // them alive too. + if (traverse_blackhole_queue()) + flag = rtsTrue; + if (flag) { goto loop; } // must be last... invariant is that everything is fully @@ -1366,16 +1372,6 @@ traverse_weak_ptr_list(void) ; } - // Threads blocked on black holes: if the black hole - // is alive, then the thread is alive too. - if (tmp == NULL && t->why_blocked == BlockedOnBlackHole) { - if (isAlive(t->block_info.closure)) { - t = (StgTSO *)evacuate((StgClosure *)t); - tmp = t; - flag = rtsTrue; - } - } - if (tmp == NULL) { // not alive (yet): leave this thread on the // old_all_threads list. @@ -1434,6 +1430,34 @@ traverse_weak_ptr_list(void) } /* ----------------------------------------------------------------------------- + The blackhole queue + + Threads on this list behave like weak pointers during the normal + phase of garbage collection: if the blackhole is reachable, then + the thread is reachable too. + -------------------------------------------------------------------------- */ +static rtsBool +traverse_blackhole_queue (void) +{ + StgTSO *prev, *t, *tmp; + rtsBool flag; + + flag = rtsFalse; + prev = NULL; + + for (t = blackhole_queue; t != END_TSO_QUEUE; prev=t, t = t->link) { + if (! (tmp = (StgTSO *)isAlive((StgClosure*)t))) { + if (isAlive(t->block_info.closure)) { + t = (StgTSO *)evacuate((StgClosure *)t); + if (prev) prev->link = t; + flag = rtsTrue; + } + } + } + return flag; +} + +/* ----------------------------------------------------------------------------- After GC, the live weak pointer list may have forwarding pointers on it, because a weak pointer object was evacuated after being moved to the live weak pointer list. We remove those forwarding |