src/share/vm/runtime/thread.cpp

*** 752,768 ****
      jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
      if (res == thread_parity) {
        return true;
      } else {
        guarantee(res == strong_roots_parity, "Or else what?");
-       assert(SharedHeap::heap()->workers()->active_workers() > 0,
-              "Should only fail when parallel.");
        return false;
      }
    }
-   assert(SharedHeap::heap()->workers()->active_workers() > 0,
-          "Should only fail when parallel.");
    return false;
  }
  
  void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
    active_handles()->oops_do(f);
--- 752,764 ----
*** 4064,4087 ****
          err_msg("Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity));
    }
  }
  #endif // PRODUCT
  
! void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
!   // Introduce a mechanism allowing parallel threads to claim threads as
!   // root groups.  Overhead should be small enough to use all the time,
!   // even in sequential code.
!   SharedHeap* sh = SharedHeap::heap();
!   // Cannot yet substitute active_workers for n_par_threads
!   // because of G1CollectedHeap::verify() use of
!   // SharedHeap::process_roots().  n_par_threads == 0 will
!   // turn off parallelism in process_roots while active_workers
!   // is being used for parallelism elsewhere.
!   bool is_par = sh->n_par_threads() > 0;
!   assert(!is_par ||
!          (SharedHeap::heap()->n_par_threads() ==
!          SharedHeap::heap()->workers()->active_workers()), "Mismatch");
    int cp = Threads::thread_claim_parity();
    ALL_JAVA_THREADS(p) {
      if (p->claim_oops_do(is_par, cp)) {
        p->oops_do(f, cld_f, cf);
      }
--- 4060,4070 ----
          err_msg("Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity));
    }
  }
  #endif // PRODUCT
  
! void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
    int cp = Threads::thread_claim_parity();
    ALL_JAVA_THREADS(p) {
      if (p->claim_oops_do(is_par, cp)) {
        p->oops_do(f, cld_f, cf);
      }