src/hotspot/share/gc/g1/vm_operations_g1.cpp

8195158: Concurrent System.gc() is "upgraded" to stop-the-world System.gc()

*** 137,153 ****
    if (_pause_succeeded) {
      if (_word_size > 0) {
        // An allocation had been requested. Do it, eventually trying a stronger
        // kind of GC.
        _result = g1h->satisfy_failed_allocation(_word_size, _allocation_context, &_pause_succeeded);
!     } else if (!g1h->has_regions_left_for_allocation()) {
!       // There has been a request to perform a GC to free some space. We have no
!       // information on how much memory has been asked for. In case there are
!       // absolutely no regions left to allocate into, do a maximally compacting full GC.
!       log_info(gc, ergo)("Attempting maximally compacting collection");
!       _pause_succeeded = g1h->do_full_collection(false, /* explicit gc */
!                                                  true   /* clear_all_soft_refs */);
      }
      guarantee(_pause_succeeded, "Elevated collections during the safepoint must always succeed.");
    } else {
      assert(_result == NULL, "invariant");
      // The only reason for the pause to not be successful is that, the GC locker is
--- 137,157 ----
    if (_pause_succeeded) {
      if (_word_size > 0) {
        // An allocation had been requested. Do it, eventually trying a stronger
        // kind of GC.
        _result = g1h->satisfy_failed_allocation(_word_size, _allocation_context, &_pause_succeeded);
!     } else {
!       bool should_upgrade_to_full = !g1h->should_do_concurrent_full_gc(_gc_cause) &&
!                                     !g1h->has_regions_left_for_allocation();
!       if (should_upgrade_to_full) {
!         // There has been a request to perform a GC to free some space. We have no
!         // information on how much memory has been asked for. In case there are
!         // absolutely no regions left to allocate into, do a maximally compacting full GC.
!         log_info(gc, ergo)("Attempting maximally compacting collection");
!         _pause_succeeded = g1h->do_full_collection(false, /* explicit gc */
!                                                    true   /* clear_all_soft_refs */);
!       }
      }
      guarantee(_pause_succeeded, "Elevated collections during the safepoint must always succeed.");
    } else {
      assert(_result == NULL, "invariant");
      // The only reason for the pause to not be successful is that, the GC locker is