src/share/vm/gc/g1/g1CollectionSet.cpp

*** 394,403 ****
--- 394,414 ----
    phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
  
    return time_remaining_ms;
  }
  
+ static int compare_region_idx(const void *a, const void*b) {
+   uint const first = *(uint*)a;
+   uint const second = *(uint*)b;
+   assert(first != second, "Two regions with the same index %u in the collection set", first);
+   if (first > second) {
+     return 1;
+   } else {
+     return -1;
+   }
+ }
+ 
  void G1CollectionSet::finalize_old_part(double time_remaining_ms) {
    double non_young_start_time_sec = os::elapsedTime();
    double predicted_old_time_ms = 0.0;
  
    if (!collector_state()->gcs_are_young()) {
*** 491,500 ****
--- 502,513 ----
    log_debug(gc, ergo, cset)("Finish choosing CSet. old: %u regions, predicted old region time: %1.2fms, time remaining: %1.2f",
                              old_region_length(), predicted_old_time_ms, time_remaining_ms);
  
    double non_young_end_time_sec = os::elapsedTime();
    phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
+ 
+   qsort(_collection_set_regions, _collection_set_cur_length, sizeof(uint), compare_region_idx);
  }
  
  #ifdef ASSERT
  class G1VerifyYoungCSetIndicesClosure : public HeapRegionClosure {
  private: