src/hotspot/share/gc/g1/g1CollectedHeap.cpp

rev 52572 : JDK-8212657: Implementation of JDK-8204089 Promptly Return Unused Committed Memory from G1
Summary: Issue optional, default enabled, concurrent cycles when the VM is idle to reclaim unused internal and Java heap memory.
Reviewed-by:
Contributed-by: Rodrigo Bruno <rbruno@gsd.inesc-id.pt>, Ruslan Synytsky <rs@jelastic.com>, Thomas Schatzl <thomas.schatzl@oracle.com>

*** 1149,1158 ****
--- 1149,1160 ----
    bool dummy = do_full_collection(true,                /* explicit_gc */
                                    clear_all_soft_refs);
  }
  
  void G1CollectedHeap::resize_heap_if_necessary() {
+   assert_at_safepoint_on_vm_thread();
+ 
    // Capacity, free and used after the GC counted as full regions to
    // include the waste in the following calculations.
    const size_t capacity_after_gc = capacity();
    const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
  
*** 1971,1980 ****
--- 1973,1983 ----
  
  bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
    switch (cause) {
      case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
      case GCCause::_g1_humongous_allocation: return true;
+     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
      default:                                return is_user_requested_concurrent_full_gc(cause);
    }
  }
  
  #ifndef PRODUCT