src/share/vm/memory/metaspace.cpp

rev 6450 : 8043639: Backout JDK-8034852: Shrinking of Metaspace high-water-mark causes incorrect OutOfMemoryErrors or back-to-back GCs

*** 1431,1443 ****
    if (!is_init_completed() || GC_locker::is_active_and_needs_gc()) {
      return left_until_max / BytesPerWord;
    }
  
    size_t capacity_until_gc = capacity_until_GC();
!   assert(capacity_until_gc >= committed_bytes,
!          err_msg("capacity_until_gc: " SIZE_FORMAT " < committed_bytes: " SIZE_FORMAT,
!                  capacity_until_gc, committed_bytes));
  
    size_t left_until_GC = capacity_until_gc - committed_bytes;
    size_t left_to_commit = MIN2(left_until_GC, left_until_max);
  
    return left_to_commit / BytesPerWord;
--- 1431,1444 ----
    if (!is_init_completed() || GC_locker::is_active_and_needs_gc()) {
      return left_until_max / BytesPerWord;
    }
  
    size_t capacity_until_gc = capacity_until_GC();
! 
!   if (capacity_until_gc <= committed_bytes) {
!     return 0;
!   }
  
    size_t left_until_GC = capacity_until_gc - committed_bytes;
    size_t left_to_commit = MIN2(left_until_GC, left_until_max);
  
    return left_to_commit / BytesPerWord;
*** 1446,1464 ****
  void MetaspaceGC::compute_new_size() {
    assert(_shrink_factor <= 100, "invalid shrink factor");
    uint current_shrink_factor = _shrink_factor;
    _shrink_factor = 0;
  
!   // Using committed_bytes() for used_after_gc is an overestimation, since the
!   // chunk free lists are included in committed_bytes() and the memory in an
!   // un-fragmented chunk free list is available for future allocations.
!   // However, if the chunk free lists becomes fragmented, then the memory may
!   // not be available for future allocations and the memory is therefore "in use".
!   // Including the chunk free lists in the definition of "in use" is therefore
!   // necessary. Not including the chunk free lists can cause capacity_until_GC to
!   // shrink below committed_bytes() and this has caused serious bugs in the past.
!   const size_t used_after_gc = MetaspaceAux::committed_bytes();
    const size_t capacity_until_GC = MetaspaceGC::capacity_until_GC();
  
    const double minimum_free_percentage = MinMetaspaceFreeRatio / 100.0;
    const double maximum_used_percentage = 1.0 - minimum_free_percentage;
  
--- 1447,1457 ----
  void MetaspaceGC::compute_new_size() {
    assert(_shrink_factor <= 100, "invalid shrink factor");
    uint current_shrink_factor = _shrink_factor;
    _shrink_factor = 0;
  
!   const size_t used_after_gc = MetaspaceAux::capacity_bytes();
    const size_t capacity_until_GC = MetaspaceGC::capacity_until_GC();
  
    const double minimum_free_percentage = MinMetaspaceFreeRatio / 100.0;
    const double maximum_used_percentage = 1.0 - minimum_free_percentage;