src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp

rev 58543 : 8241605: Shenandoah: More aggressive reference discovery

*** 180,202 ****
    }
  };
  
  class ShenandoahSATBAndRemarkCodeRootsThreadsClosure : public ThreadClosure {
  private:
!   ShenandoahSATBBufferClosure* _satb_cl;
!   MarkingCodeBlobClosure*      _code_cl;
    uintx _claim_token;
- 
  public:
!   ShenandoahSATBAndRemarkCodeRootsThreadsClosure(ShenandoahSATBBufferClosure* satb_cl, MarkingCodeBlobClosure* code_cl) :
!     _satb_cl(satb_cl), _code_cl(code_cl),
      _claim_token(Threads::thread_claim_token()) {}
  
    void do_thread(Thread* thread) {
      if (thread->claim_threads_do(true, _claim_token)) {
        ShenandoahThreadLocalData::satb_mark_queue(thread).apply_closure_and_empty(_satb_cl);
!       if (_code_cl != NULL && thread->is_Java_thread()) {
          // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
          // however the liveness of oops reachable from nmethods have very complex lifecycles:
          // * Alive if on the stack of an executing method
          // * Weakly reachable otherwise
          // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
--- 180,210 ----
    }
  };
  
  class ShenandoahSATBAndRemarkCodeRootsThreadsClosure : public ThreadClosure {
  private:
!   ShenandoahSATBBufferClosure* const _satb_cl;
!   OopClosure*                  const _cl;
!   MarkingCodeBlobClosure*      const _code_cl;
    uintx _claim_token;
  public:
!   ShenandoahSATBAndRemarkCodeRootsThreadsClosure(ShenandoahSATBBufferClosure* satb_cl,
!                                                  OopClosure* cl, MarkingCodeBlobClosure* code_cl) :
!     _satb_cl(satb_cl), _cl(cl), _code_cl(code_cl),
      _claim_token(Threads::thread_claim_token()) {}
  
    void do_thread(Thread* thread) {
      if (thread->claim_threads_do(true, _claim_token)) {
        ShenandoahThreadLocalData::satb_mark_queue(thread).apply_closure_and_empty(_satb_cl);
!       if (_cl != NULL) {
!         // This doesn't appear to add very much to final-mark latency. If that ever becomes a problem,
!         // we can attempt to trim it to only scan actual thread-stacks (and avoid stuff like handles, monitors, etc)
!         // and there only compiled frames. We can also make thread-scans templatized to avoid virtual calls and
!         // instead inline the closures.
!         ResourceMark rm;
!         thread->oops_do(_cl, _code_cl);
!       } else if (_code_cl != NULL && thread->is_Java_thread()) {
          // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
          // however the liveness of oops reachable from nmethods have very complex lifecycles:
          // * Alive if on the stack of an executing method
          // * Weakly reachable otherwise
          // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
*** 241,264 ****
  
        ShenandoahSATBBufferClosure cl(q);
        SATBMarkQueueSet& satb_mq_set = ShenandoahBarrierSet::satb_mark_queue_set();
        while (satb_mq_set.apply_closure_to_completed_buffer(&cl));
  
!       if (heap->unload_classes() && !ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
          if (heap->has_forwarded_objects()) {
            ShenandoahMarkResolveRefsClosure resolve_mark_cl(q, rp);
            MarkingCodeBlobClosure blobsCl(&resolve_mark_cl, !CodeBlobToOopClosure::FixRelocations);
!           ShenandoahSATBAndRemarkCodeRootsThreadsClosure tc(&cl, &blobsCl);
            Threads::threads_do(&tc);
          } else {
            ShenandoahMarkRefsClosure mark_cl(q, rp);
            MarkingCodeBlobClosure blobsCl(&mark_cl, !CodeBlobToOopClosure::FixRelocations);
!           ShenandoahSATBAndRemarkCodeRootsThreadsClosure tc(&cl, &blobsCl);
!           Threads::threads_do(&tc);
!         }
!       } else {
!         ShenandoahSATBAndRemarkCodeRootsThreadsClosure tc(&cl, NULL);
          Threads::threads_do(&tc);
        }
      }
  
      if (heap->is_degenerated_gc_in_progress()) {
--- 249,272 ----
  
        ShenandoahSATBBufferClosure cl(q);
        SATBMarkQueueSet& satb_mq_set = ShenandoahBarrierSet::satb_mark_queue_set();
        while (satb_mq_set.apply_closure_to_completed_buffer(&cl));
  
!       bool do_nmethods = heap->unload_classes() && !ShenandoahConcurrentRoots::can_do_concurrent_class_unloading();
        if (heap->has_forwarded_objects()) {
          ShenandoahMarkResolveRefsClosure resolve_mark_cl(q, rp);
          MarkingCodeBlobClosure blobsCl(&resolve_mark_cl, !CodeBlobToOopClosure::FixRelocations);
!         ShenandoahSATBAndRemarkCodeRootsThreadsClosure tc(&cl,
!                                                           ShenandoahAggressiveReferenceDiscovery ? &resolve_mark_cl : NULL,
!                                                           do_nmethods ? &blobsCl : NULL);
          Threads::threads_do(&tc);
        } else {
          ShenandoahMarkRefsClosure mark_cl(q, rp);
          MarkingCodeBlobClosure blobsCl(&mark_cl, !CodeBlobToOopClosure::FixRelocations);
!         ShenandoahSATBAndRemarkCodeRootsThreadsClosure tc(&cl,
!                                                           ShenandoahAggressiveReferenceDiscovery ? &mark_cl : NULL,
!                                                           do_nmethods ? &blobsCl : NULL);
          Threads::threads_do(&tc);
        }
      }
  
      if (heap->is_degenerated_gc_in_progress()) {