*** old/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Fri Aug 29 15:59:14 2014
--- new/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Fri Aug 29 15:59:14 2014

*** 5047,5057 ****
--- 5047,5061 ----
        _claimed_nmethod(NULL),
        _postponed_list(NULL),
        _num_entered_barrier(0)
    {
      nmethod::increase_unloading_clock();
      _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
+     // Get first alive nmethod
+     NMethodIterator iter = NMethodIterator();
+     if(iter.next_alive()) {
+       _first_nmethod = iter.method();
+     }
      _claimed_nmethod = (volatile nmethod*)_first_nmethod;
    }
  
    ~G1CodeCacheUnloadingTask() {
      CodeCache::verify_clean_inline_caches();

*** 5090,5120 ****
--- 5094,5123 ----
  
    static const int MaxClaimNmethods = 16;
  
    void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
      nmethod* first;
!     nmethod* last;
!     NMethodIterator last;
  
      do {
        *num_claimed_nmethods = 0;
  
-       first = last = (nmethod*)_claimed_nmethod;
+       last = NMethodIterator(first);
  
        if (first != NULL) {
          for (int i = 0; i < MaxClaimNmethods; i++) {
            last = CodeCache::alive_nmethod(CodeCache::next(last));
  
!           if (last == NULL) {
!         for (int i = 0; i < MaxClaimNmethods; i++) {
+           if (!last.next_alive()) {
              break;
            }
  
            claimed_nmethods[i] = last;
+           claimed_nmethods[i] = last.method();
            (*num_claimed_nmethods)++;
          }
        }
  
!     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
    }
  
    nmethod* claim_postponed_nmethod() {
      nmethod* claim;
      nmethod* next;