8024638: Count and expose the amount of committed memory in the metaspaces

Reviewed-by: brutisso, ehelin

src/share/vm/memory/metaspace.cpp

@@ -291,6 +291,10 @@ class VirtualSpaceNode : public CHeapObj<mtClass> {
   MetaWord* bottom() const { return (MetaWord*) _virtual_space.low(); }
   MetaWord* end() const { return (MetaWord*) _virtual_space.high(); }
 
+  size_t reserved_words() const  { return _virtual_space.reserved_size() / BytesPerWord; }
+  size_t expanded_words() const  { return _virtual_space.committed_size() / BytesPerWord; }
+  size_t committed_words() const { return _virtual_space.actual_committed_size() / BytesPerWord; }
+
   // address of next available space in _virtual_space;
   // Accessors
   VirtualSpaceNode* next() { return _next; }
@@ -327,12 +331,10 @@ class VirtualSpaceNode : public CHeapObj<mtClass> {
 
   // Allocate a chunk from the virtual space and return it.
   Metachunk* get_chunk_vs(size_t chunk_word_size);
-  Metachunk* get_chunk_vs_with_expand(size_t chunk_word_size);
 
   // Expands/shrinks the committed space in a virtual space.  Delegates
   // to Virtualspace
   bool expand_by(size_t words, bool pre_touch = false);
-  bool shrink_by(size_t words);
 
   // In preparation for deleting this node, remove all the chunks
   // in the node from any freelist.
@@ -340,8 +342,6 @@ class VirtualSpaceNode : public CHeapObj<mtClass> {
 
 #ifdef ASSERT
   // Debug support
-  static void verify_virtual_space_total();
-  static void verify_virtual_space_count();
   void mangle();
 #endif
 
@@ -429,8 +429,11 @@ class VirtualSpaceList : public CHeapObj<mtClass> {
   bool _is_class;
   bool can_grow() const { return !is_class() || !UseCompressedClassPointers; }
 
-  // Sum of space in all virtual spaces and number of virtual spaces
-  size_t _virtual_space_total;
+  // Sum of reserved and committed memory in the virtual spaces
+  size_t _reserved_words;
+  size_t _committed_words;
+
+  // Number of virtual spaces
   size_t _virtual_space_count;
 
   ~VirtualSpaceList();
@@ -444,7 +447,7 @@ class VirtualSpaceList : public CHeapObj<mtClass> {
     _current_virtual_space = v;
   }
 
-  void link_vs(VirtualSpaceNode* new_entry, size_t vs_word_size);
+  void link_vs(VirtualSpaceNode* new_entry);
 
   // Get another virtual space and add it to the list.  This
   // is typically prompted by a failed attempt to allocate a chunk
@@ -461,6 +464,8 @@ class VirtualSpaceList : public CHeapObj<mtClass> {
                            size_t grow_chunks_by_words,
                            size_t medium_chunk_bunch);
 
+  bool expand_by(VirtualSpaceNode* node, size_t word_size, bool pre_touch = false);
+
   // Get the first chunk for a Metaspace.  Used for
   // special cases such as the boot class loader, reflection
   // class loader and anonymous class loader.
@@ -476,10 +481,15 @@ class VirtualSpaceList : public CHeapObj<mtClass> {
   // Allocate the first virtualspace.
   void initialize(size_t word_size);
 
-  size_t virtual_space_total() { return _virtual_space_total; }
+  size_t reserved_words()  { return _reserved_words; }
+  size_t reserved_bytes()  { return reserved_words() * BytesPerWord; }
+  size_t committed_words() { return _committed_words; }
+  size_t committed_bytes() { return committed_words() * BytesPerWord; }
 
-  void inc_virtual_space_total(size_t v);
-  void dec_virtual_space_total(size_t v);
+  void inc_reserved_words(size_t v);
+  void dec_reserved_words(size_t v);
+  void inc_committed_words(size_t v);
+  void dec_committed_words(size_t v);
   void inc_virtual_space_count();
   void dec_virtual_space_count();
 
@@ -901,15 +911,6 @@ bool VirtualSpaceNode::expand_by(size_t words, bool pre_touch) {
   return result;
 }
 
-// Shrink the virtual space (commit more of the reserved space)
-bool VirtualSpaceNode::shrink_by(size_t words) {
-  size_t bytes = words * BytesPerWord;
-  virtual_space()->shrink_by(bytes);
-  return true;
-}
-
-// Add another chunk to the chunk list.
-
 Metachunk* VirtualSpaceNode::get_chunk_vs(size_t chunk_word_size) {
   assert_lock_strong(SpaceManager::expand_lock());
   Metachunk* result = take_from_committed(chunk_word_size);
@@ -919,23 +920,6 @@ Metachunk* VirtualSpaceNode::get_chunk_vs(size_t chunk_word_size) {
   return result;
 }
 
-Metachunk* VirtualSpaceNode::get_chunk_vs_with_expand(size_t chunk_word_size) {
-  assert_lock_strong(SpaceManager::expand_lock());
-
-  Metachunk* new_chunk = get_chunk_vs(chunk_word_size);
-
-  if (new_chunk == NULL) {
-    // Only a small part of the virtualspace is committed when first
-    // allocated so committing more here can be expected.
-    size_t page_size_words = os::vm_page_size() / BytesPerWord;
-    size_t aligned_expand_vs_by_words = align_size_up(chunk_word_size,
-                                                    page_size_words);
-    expand_by(aligned_expand_vs_by_words, false);
-    new_chunk = get_chunk_vs(chunk_word_size);
-  }
-  return new_chunk;
-}
-
 bool VirtualSpaceNode::initialize() {
 
   if (!_rs.is_reserved()) {
@@ -995,13 +979,22 @@ VirtualSpaceList::~VirtualSpaceList() {
   }
 }
 
-void VirtualSpaceList::inc_virtual_space_total(size_t v) {
+void VirtualSpaceList::inc_reserved_words(size_t v) {
   assert_lock_strong(SpaceManager::expand_lock());
-  _virtual_space_total = _virtual_space_total + v;
+  _reserved_words = _reserved_words + v;
 }
-void VirtualSpaceList::dec_virtual_space_total(size_t v) {
+void VirtualSpaceList::dec_reserved_words(size_t v) {
   assert_lock_strong(SpaceManager::expand_lock());
-  _virtual_space_total = _virtual_space_total - v;
+  _reserved_words = _reserved_words - v;
+}
+
+void VirtualSpaceList::inc_committed_words(size_t v) {
+  assert_lock_strong(SpaceManager::expand_lock());
+  _committed_words = _committed_words + v;
+}
+void VirtualSpaceList::dec_committed_words(size_t v) {
+  assert_lock_strong(SpaceManager::expand_lock());
+  _committed_words = _committed_words - v;
 }
 
 void VirtualSpaceList::inc_virtual_space_count() {
@@ -1052,7 +1045,8 @@ void VirtualSpaceList::purge() {
       }
 
       vsl->purge(chunk_manager());
-      dec_virtual_space_total(vsl->reserved()->word_size());
+      dec_reserved_words(vsl->reserved_words());
+      dec_committed_words(vsl->committed_words());
       dec_virtual_space_count();
       purged_vsl = vsl;
       delete vsl;
@@ -1106,7 +1100,8 @@ VirtualSpaceList::VirtualSpaceList(size_t word_size ) :
                                    _is_class(false),
                                    _virtual_space_list(NULL),
                                    _current_virtual_space(NULL),
-                                   _virtual_space_total(0),
+                                   _reserved_words(0),
+                                   _committed_words(0),
                                    _virtual_space_count(0) {
   MutexLockerEx cl(SpaceManager::expand_lock(),
                    Mutex::_no_safepoint_check_flag);
@@ -1123,7 +1118,8 @@ VirtualSpaceList::VirtualSpaceList(ReservedSpace rs) :
                                    _is_class(true),
                                    _virtual_space_list(NULL),
                                    _current_virtual_space(NULL),
-                                   _virtual_space_total(0),
+                                   _reserved_words(0),
+                                   _committed_words(0),
                                    _virtual_space_count(0) {
   MutexLockerEx cl(SpaceManager::expand_lock(),
                    Mutex::_no_safepoint_check_flag);
@@ -1133,7 +1129,7 @@ VirtualSpaceList::VirtualSpaceList(ReservedSpace rs) :
   _chunk_manager.free_chunks(SmallIndex)->set_size(ClassSmallChunk);
   _chunk_manager.free_chunks(MediumIndex)->set_size(ClassMediumChunk);
   assert(succeeded, " VirtualSpaceList initialization should not fail");
-  link_vs(class_entry, rs.size()/BytesPerWord);
+  link_vs(class_entry);
 }
 
 size_t VirtualSpaceList::free_bytes() {
@@ -1156,21 +1152,23 @@ bool VirtualSpaceList::grow_vs(size_t vs_word_size) {
     delete new_entry;
     return false;
   } else {
+    assert(new_entry->reserved_words() == vs_word_size, "Must be");
     // ensure lock-free iteration sees fully initialized node
     OrderAccess::storestore();
-    link_vs(new_entry, vs_word_size);
+    link_vs(new_entry);
     return true;
   }
 }
 
-void VirtualSpaceList::link_vs(VirtualSpaceNode* new_entry, size_t vs_word_size) {
+void VirtualSpaceList::link_vs(VirtualSpaceNode* new_entry) {
   if (virtual_space_list() == NULL) {
       set_virtual_space_list(new_entry);
   } else {
     current_virtual_space()->set_next(new_entry);
   }
   set_current_virtual_space(new_entry);
-  inc_virtual_space_total(vs_word_size);
+  inc_reserved_words(new_entry->reserved_words());
+  inc_committed_words(new_entry->committed_words());
   inc_virtual_space_count();
 #ifdef ASSERT
   new_entry->mangle();
@@ -1181,6 +1179,20 @@ void VirtualSpaceList::link_vs(VirtualSpaceNode* new_entry, size_t vs_word_size)
   }
 }
 
+bool VirtualSpaceList::expand_by(VirtualSpaceNode* node, size_t word_size, bool pre_touch) {
+  size_t before = node->committed_words();
+
+  bool result = node->expand_by(word_size, pre_touch);
+
+  size_t after = node->committed_words();
+
+  // after and before can be the same if the memory was pre-committed.
+  assert(after >= before, "Must be");
+  inc_committed_words(after - before);
+
+  return result;
+}
+
 Metachunk* VirtualSpaceList::get_new_chunk(size_t word_size,
                                            size_t grow_chunks_by_words,
                                            size_t medium_chunk_bunch) {
@@ -1204,7 +1216,7 @@ Metachunk* VirtualSpaceList::get_new_chunk(size_t word_size,
     size_t aligned_expand_vs_by_words = align_size_up(expand_vs_by_words,
                                                         page_size_words);
     bool vs_expanded =
-      current_virtual_space()->expand_by(aligned_expand_vs_by_words, false);
+      expand_by(current_virtual_space(), aligned_expand_vs_by_words);
     if (!vs_expanded) {
       // Should the capacity of the metaspaces be expanded for
       // this allocation?  If it's the virtual space for classes and is
@@ -1215,7 +1227,14 @@ Metachunk* VirtualSpaceList::get_new_chunk(size_t word_size,
             MAX2((size_t)VirtualSpaceSize, aligned_expand_vs_by_words);
         if (grow_vs(grow_vs_words)) {
           // Got it.  It's on the list now.  Get a chunk from it.
-          next = current_virtual_space()->get_chunk_vs_with_expand(grow_chunks_by_words);
+          assert(current_virtual_space()->expanded_words() == 0,
+              "New virtuals space nodes should not have expanded");
+
+          size_t grow_chunks_by_words_aligned = align_size_up(grow_chunks_by_words,
+                                                              page_size_words);
+          // We probably want to expand by aligned_expand_vs_by_words here.
+          expand_by(current_virtual_space(), grow_chunks_by_words_aligned);
+          next = current_virtual_space()->get_chunk_vs(grow_chunks_by_words);
         }
       } else {
         // Allocation will fail and induce a GC
@@ -1325,7 +1344,7 @@ bool MetaspaceGC::should_expand(VirtualSpaceList* vsl, size_t word_size) {
   // reserved space, because this is a larger space prereserved for compressed
   // class pointers.
   if (!FLAG_IS_DEFAULT(MaxMetaspaceSize)) {
-    size_t real_allocated = Metaspace::space_list()->virtual_space_total() +
+    size_t real_allocated = Metaspace::space_list()->reserved_words() +
               MetaspaceAux::allocated_capacity_bytes(Metaspace::ClassType);
     if (real_allocated >= MaxMetaspaceSize) {
       return false;
@@ -2615,7 +2634,12 @@ size_t MetaspaceAux::capacity_bytes_slow() {
 
 size_t MetaspaceAux::reserved_bytes(Metaspace::MetadataType mdtype) {
   VirtualSpaceList* list = Metaspace::get_space_list(mdtype);
-  return list == NULL ? 0 : list->virtual_space_total() * BytesPerWord;
+  return list == NULL ? 0 : list->reserved_bytes();
+}
+
+size_t MetaspaceAux::committed_bytes(Metaspace::MetadataType mdtype) {
+  VirtualSpaceList* list = Metaspace::get_space_list(mdtype);
+  return list == NULL ? 0 : list->committed_bytes();
 }
 
 size_t MetaspaceAux::min_chunk_size_words() { return Metaspace::first_chunk_word_size(); }
@@ -3357,3 +3381,59 @@ void Metaspace::dump(outputStream* const out) const {
     class_vsm()->dump(out);
   }
 }
+
+/////////////// Unit tests ///////////////
+
+#ifndef PRODUCT
+
+class MetaspaceAuxTest : AllStatic {
+ public:
+  static void test_reserved() {
+    size_t reserved = MetaspaceAux::reserved_bytes();
+
+    assert(reserved > 0, "assert");
+
+    size_t committed  = MetaspaceAux::committed_bytes();
+    assert(committed <= reserved, "assert");
+
+    size_t reserved_metadata = MetaspaceAux::reserved_bytes(Metaspace::NonClassType);
+    assert(reserved_metadata > 0, "assert");
+    assert(reserved_metadata <= reserved, "assert");
+
+    if (UseCompressedClassPointers) {
+      size_t reserved_class    = MetaspaceAux::reserved_bytes(Metaspace::ClassType);
+      assert(reserved_class > 0, "assert");
+      assert(reserved_class < reserved, "assert");
+    }
+  }
+
+  static void test_committed() {
+    size_t committed = MetaspaceAux::committed_bytes();
+
+    assert(committed > 0, "assert");
+
+    size_t reserved  = MetaspaceAux::reserved_bytes();
+    assert(committed <= reserved, "assert");
+
+    size_t committed_metadata = MetaspaceAux::committed_bytes(Metaspace::NonClassType);
+    assert(committed_metadata > 0, "assert");
+    assert(committed_metadata <= committed, "assert");
+
+    if (UseCompressedClassPointers) {
+      size_t committed_class    = MetaspaceAux::committed_bytes(Metaspace::ClassType);
+      assert(committed_class > 0, "assert");
+      assert(committed_class < committed, "assert");
+    }
+  }
+
+  static void test() {
+    test_reserved();
+    test_committed();
+  }
+};
+
+void MetaspaceAux_test() {
+  MetaspaceAuxTest::test();
+}
+
+#endif

src/share/vm/memory/metaspace.hpp

@@ -292,13 +292,18 @@ class MetaspaceAux : AllStatic {
   static size_t free_bytes();
   static size_t free_bytes(Metaspace::MetadataType mdtype);
 
-  // Total capacity in all Metaspaces
   static size_t reserved_bytes(Metaspace::MetadataType mdtype);
   static size_t reserved_bytes() {
     return reserved_bytes(Metaspace::ClassType) +
            reserved_bytes(Metaspace::NonClassType);
   }
 
+  static size_t committed_bytes(Metaspace::MetadataType mdtype);
+  static size_t committed_bytes() {
+    return committed_bytes(Metaspace::ClassType) +
+           committed_bytes(Metaspace::NonClassType);
+  }
+
   static size_t min_chunk_size_words();
   static size_t min_chunk_size_bytes() {
     return min_chunk_size_words() * BytesPerWord;

src/share/vm/prims/jni.cpp

@@ -5048,12 +5048,16 @@ _JNI_IMPORT_OR_EXPORT_ jint JNICALL JNI_GetDefaultJavaVMInitArgs(void *args_) {
 // Forward declaration
 void TestReservedSpace_test();
 void TestReserveMemorySpecial_test();
+void TestVirtualSpace_test();
+void MetaspaceAux_test();
 
 void execute_internal_vm_tests() {
   if (ExecuteInternalVMTests) {
     tty->print_cr("Running internal VM tests");
     run_unit_test(TestReservedSpace_test());
     run_unit_test(TestReserveMemorySpecial_test());
+    run_unit_test(TestVirtualSpace_test());
+    run_unit_test(MetaspaceAux_test());
     run_unit_test(GlobalDefinitions::test_globals());
     run_unit_test(GCTimerAllTest::all());
     run_unit_test(arrayOopDesc::test_max_array_length());

src/share/vm/runtime/virtualspace.cpp

@@ -453,6 +453,42 @@ size_t VirtualSpace::uncommitted_size()  const {
   return reserved_size() - committed_size();
 }
 
+size_t VirtualSpace::actual_committed_size() const {
+  // Special VirtualSpaces commit all reserved space up front.
+  if (special()) {
+    return reserved_size();
+  }
+
+  size_t committed_low    = pointer_delta(_lower_high,  _low_boundary,         sizeof(char));
+  size_t committed_middle = pointer_delta(_middle_high, _lower_high_boundary,  sizeof(char));
+  size_t committed_high   = pointer_delta(_upper_high,  _middle_high_boundary, sizeof(char));
+
+#ifdef ASSERT
+  size_t lower  = pointer_delta(_lower_high_boundary,  _low_boundary,         sizeof(char));
+  size_t middle = pointer_delta(_middle_high_boundary, _lower_high_boundary,  sizeof(char));
+  size_t upper  = pointer_delta(_upper_high_boundary,  _middle_high_boundary, sizeof(char));
+
+  if (committed_high > 0) {
+    assert(committed_low == lower, "Must be");
+    assert(committed_middle == middle, "Must be");
+  }
+
+  if (committed_middle > 0) {
+    assert(committed_low == lower, "Must be");
+  }
+  if (committed_middle < middle) {
+    assert(committed_high == 0, "Must be");
+  }
+
+  if (committed_low < lower) {
+    assert(committed_high == 0, "Must be");
+    assert(committed_middle == 0, "Must be");
+  }
+#endif
+
+  return committed_low + committed_middle + committed_high;
+}
+
 
 bool VirtualSpace::contains(const void* p) const {
   return low() <= (const char*) p && (const char*) p < high();
@@ -910,6 +946,109 @@ void TestReservedSpace_test() {
   TestReservedSpace::test_reserved_space();
 }
 
+#define assert_equals(actual, expected)     \
+  assert(actual == expected,                \
+    err_msg("Got " SIZE_FORMAT " expected " \
+      SIZE_FORMAT, actual, expected));
+
+#define assert_ge(value1, value2)                  \
+  assert(value1 >= value2,                         \
+    err_msg("'" #value1 "': " SIZE_FORMAT " '"     \
+      #value2 "': " SIZE_FORMAT, value1, value2));
+
+#define assert_lt(value1, value2)                  \
+  assert(value1 < value2,                          \
+    err_msg("'" #value1 "': " SIZE_FORMAT " '"     \
+      #value2 "': " SIZE_FORMAT, value1, value2));
+
+
+class TestVirtualSpace : AllStatic {
+ public:
+  static void test_virtual_space_actual_committed_space(size_t reserve_size, size_t commit_size) {
+    size_t granularity = os::vm_allocation_granularity();
+    size_t reserve_size_aligned = align_size_up(reserve_size, granularity);
+
+    ReservedSpace reserved(reserve_size_aligned);
+
+    assert(reserved.is_reserved(), "Must be");
+
+    VirtualSpace vs;
+    bool initialized = vs.initialize(reserved, 0);
+    assert(initialized, "Failed to initialize VirtualSpace");
+
+    vs.expand_by(commit_size, false);
+
+    if (vs.special()) {
+      assert_equals(vs.actual_committed_size(), reserve_size_aligned);
+    } else {
+      assert_ge(vs.actual_committed_size(), commit_size);
+      // Approximate the commit granularity.
+      size_t commit_granularity = UseLargePages ? os::large_page_size() : os::vm_page_size();
+      assert_lt(vs.actual_committed_size(), commit_size + commit_granularity);
+    }
+
+    reserved.release();
+  }
+
+  static void test_virtual_space_actual_committed_space_one_large_page() {
+    if (!UseLargePages) {
+      return;
+    }
+
+    size_t large_page_size = os::large_page_size();
+
+    ReservedSpace reserved(large_page_size, large_page_size, true, false);
+
+    assert(reserved.is_reserved(), "Must be");
+
+    VirtualSpace vs;
+    bool initialized = vs.initialize(reserved, 0);
+    assert(initialized, "Failed to initialize VirtualSpace");
+
+    vs.expand_by(large_page_size, false);
+
+    assert_equals(vs.actual_committed_size(), large_page_size);
+
+    reserved.release();
+  }
+
+  static void test_virtual_space_actual_committed_space() {
+    test_virtual_space_actual_committed_space(4 * K, 0);
+    test_virtual_space_actual_committed_space(4 * K, 4 * K);
+    test_virtual_space_actual_committed_space(8 * K, 0);
+    test_virtual_space_actual_committed_space(8 * K, 4 * K);
+    test_virtual_space_actual_committed_space(8 * K, 8 * K);
+    test_virtual_space_actual_committed_space(12 * K, 0);
+    test_virtual_space_actual_committed_space(12 * K, 4 * K);
+    test_virtual_space_actual_committed_space(12 * K, 8 * K);
+    test_virtual_space_actual_committed_space(12 * K, 12 * K);
+    test_virtual_space_actual_committed_space(64 * K, 0);
+    test_virtual_space_actual_committed_space(64 * K, 32 * K);
+    test_virtual_space_actual_committed_space(64 * K, 64 * K);
+    test_virtual_space_actual_committed_space(2 * M, 0);
+    test_virtual_space_actual_committed_space(2 * M, 4 * K);
+    test_virtual_space_actual_committed_space(2 * M, 64 * K);
+    test_virtual_space_actual_committed_space(2 * M, 1 * M);
+    test_virtual_space_actual_committed_space(2 * M, 2 * M);
+    test_virtual_space_actual_committed_space(10 * M, 0);
+    test_virtual_space_actual_committed_space(10 * M, 4 * K);
+    test_virtual_space_actual_committed_space(10 * M, 8 * K);
+    test_virtual_space_actual_committed_space(10 * M, 1 * M);
+    test_virtual_space_actual_committed_space(10 * M, 2 * M);
+    test_virtual_space_actual_committed_space(10 * M, 5 * M);
+    test_virtual_space_actual_committed_space(10 * M, 10 * M);
+  }
+
+  static void test_virtual_space() {
+    test_virtual_space_actual_committed_space();
+    test_virtual_space_actual_committed_space_one_large_page();
+  }
+};
+
+void TestVirtualSpace_test() {
+  TestVirtualSpace::test_virtual_space();
+}
+
 #endif // PRODUCT
 
 #endif

src/share/vm/runtime/virtualspace.hpp

@@ -183,11 +183,16 @@ class VirtualSpace VALUE_OBJ_CLASS_SPEC {
   // Destruction
   ~VirtualSpace();
 
-  // Testers (all sizes are byte sizes)
-  size_t committed_size()   const;
-  size_t reserved_size()    const;
+  // Reserved memory
+  size_t reserved_size() const;
+  // Actually committed OS memory
+  size_t actual_committed_size() const;
+  // Memory used/expanded in this virtual space
+  size_t committed_size() const;
+  // Memory left to use/expand in this virtual space
   size_t uncommitted_size() const;
-  bool   contains(const void* p)  const;
+
+  bool   contains(const void* p) const;
 
   // Operations
   // returns true on success, false otherwise