Merge

src/share/vm/classfile/classLoaderStats.cpp

+/*
+ * Copyright (c) 2014, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/classLoaderStats.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+
+class ClassStatsClosure : public KlassClosure {
+public:
+  int _num_classes;
+
+  ClassStatsClosure() :
+    _num_classes(0) {
+  }
+
+  virtual void do_klass(Klass* k) {
+    _num_classes++;
+  }
+};
+
+
+void ClassLoaderStatsClosure::do_cld(ClassLoaderData* cld) {
+  oop cl = cld->class_loader();
+  ClassLoaderStats* cls;
+
+  // The hashtable key is the ClassLoader oop since we want to account
+  // for "real" classes and anonymous classes together
+  ClassLoaderStats** cls_ptr = _stats->get(cl);
+  if (cls_ptr == NULL) {
+    cls = new ClassLoaderStats();
+    _stats->put(cl, cls);
+    _total_loaders++;
+  } else {
+    cls = *cls_ptr;
+  }
+
+  if (!cld->is_anonymous()) {
+    cls->_cld = cld;
+  }
+
+  cls->_class_loader = cl;
+  if (cl != NULL) {
+    cls->_parent = java_lang_ClassLoader::parent(cl);
+    addEmptyParents(cls->_parent);
+  }
+
+  ClassStatsClosure csc;
+  cld->classes_do(&csc);
+  if(cld->is_anonymous()) {
+    cls->_anon_classes_count += csc._num_classes;
+  } else {
+    cls->_classes_count = csc._num_classes;
+  }
+  _total_classes += csc._num_classes;
+
+  Metaspace* ms = cld->metaspace_or_null();
+  if (ms != NULL) {
+    if(cld->is_anonymous()) {
+      cls->_anon_chunk_sz += ms->allocated_chunks_bytes();
+      cls->_anon_block_sz += ms->allocated_blocks_bytes();
+    } else {
+      cls->_chunk_sz = ms->allocated_chunks_bytes();
+      cls->_block_sz = ms->allocated_blocks_bytes();
+    }
+    _total_chunk_sz += ms->allocated_chunks_bytes();
+    _total_block_sz += ms->allocated_blocks_bytes();
+  }
+}
+
+
+// Handles the difference in pointer width on 32 and 64 bit platforms
+#ifdef _LP64
+  #define SPACE "%8s"
+#else
+  #define SPACE "%s"
+#endif
+
+
+bool ClassLoaderStatsClosure::do_entry(oop const& key, ClassLoaderStats* const& cls) {
+  Klass* class_loader_klass = (cls->_class_loader == NULL ? NULL : cls->_class_loader->klass());
+  Klass* parent_klass = (cls->_parent == NULL ? NULL : cls->_parent->klass());
+
+  _out->print(INTPTR_FORMAT "  " INTPTR_FORMAT "  " INTPTR_FORMAT "  " UINTX_FORMAT_W(6) "  " SIZE_FORMAT_W(8) "  " SIZE_FORMAT_W(8) "  ",
+      p2i(class_loader_klass), p2i(parent_klass), p2i(cls->_cld),
+      cls->_classes_count,
+      cls->_chunk_sz, cls->_block_sz);
+  if (class_loader_klass != NULL) {
+    _out->print("%s", class_loader_klass->external_name());
+  } else {
+    _out->print("<boot class loader>");
+  }
+  _out->cr();
+  if (cls->_anon_classes_count > 0) {
+    _out->print_cr(SPACE SPACE SPACE "                                    " UINTX_FORMAT_W(6) "  " SIZE_FORMAT_W(8) "  " SIZE_FORMAT_W(8) "   + unsafe anonymous classes",
+        "", "", "",
+        cls->_anon_classes_count,
+        cls->_anon_chunk_sz, cls->_anon_block_sz);
+  }
+  return true;
+}
+
+
+void ClassLoaderStatsClosure::print() {
+  _out->print_cr("ClassLoader" SPACE " Parent" SPACE "      CLD*" SPACE "       Classes   ChunkSz   BlockSz  Type", "", "", "");
+  _stats->iterate(this);
+  _out->print("Total = " UINTX_FORMAT_W(-6), _total_loaders);
+  _out->print(SPACE SPACE SPACE "                      ", "", "", "");
+  _out->print_cr(UINTX_FORMAT_W(6) "  " SIZE_FORMAT_W(8) "  " SIZE_FORMAT_W(8) "  ",
+      _total_classes,
+      _total_chunk_sz,
+      _total_block_sz);
+  _out->print_cr("ChunkSz: Total size of all allocated metaspace chunks");
+  _out->print_cr("BlockSz: Total size of all allocated metaspace blocks (each chunk has several blocks)");
+}
+
+
+void ClassLoaderStatsClosure::addEmptyParents(oop cl) {
+  while (cl != NULL && java_lang_ClassLoader::loader_data(cl) == NULL) {
+    // This classloader has not loaded any classes
+    ClassLoaderStats** cls_ptr = _stats->get(cl);
+    if (cls_ptr == NULL) {
+      // It does not exist in our table - add it
+      ClassLoaderStats* cls = new ClassLoaderStats();
+      cls->_class_loader = cl;
+      cls->_parent = java_lang_ClassLoader::parent(cl);
+      _stats->put(cl, cls);
+      _total_loaders++;
+    }
+
+    cl = java_lang_ClassLoader::parent(cl);
+  }
+}
+
+
+void ClassLoaderStatsVMOperation::doit() {
+  ClassLoaderStatsClosure clsc (_out);
+  ClassLoaderDataGraph::cld_do(&clsc);
+  clsc.print();
+}
+
+
+void ClassLoaderStatsDCmd::execute(DCmdSource source, TRAPS) {
+  ClassLoaderStatsVMOperation op(output());
+  VMThread::execute(&op);
+}

src/share/vm/classfile/classLoaderStats.hpp

+/*
+ * Copyright (c) 2014, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_CLASSFILE_CLASSLOADERSTATS_HPP
+#define SHARE_VM_CLASSFILE_CLASSLOADERSTATS_HPP
+
+
+#include "classfile/classLoaderData.hpp"
+#include "oops/klass.hpp"
+#include "oops/oopsHierarchy.hpp"
+#include "runtime/vm_operations.hpp"
+#include "services/diagnosticCommand.hpp"
+#include "utilities/resourceHash.hpp"
+
+
+class ClassLoaderStatsDCmd : public DCmd {
+public:
+  ClassLoaderStatsDCmd(outputStream* output, bool heap) :
+    DCmd(output, heap) {
+  }
+
+  static const char* name() {
+    return "VM.classloader_stats";
+  }
+
+  static const char* description() {
+    return "Print statistics about all ClassLoaders.";
+  }
+
+  static const char* impact() {
+    return "Low";
+  }
+
+  virtual void execute(DCmdSource source, TRAPS);
+
+  static int num_arguments() {
+    return 0;
+  }
+
+  static const JavaPermission permission() {
+    JavaPermission p = {"java.lang.management.ManagementPermission",
+                        "monitor", NULL};
+    return p;
+  }
+};
+
+
+class ClassLoaderStats : public ResourceObj {
+public:
+  ClassLoaderData*  _cld;
+  oop               _class_loader;
+  oop               _parent;
+
+  size_t            _chunk_sz;
+  size_t            _block_sz;
+  uintx             _classes_count;
+
+  size_t            _anon_chunk_sz;
+  size_t            _anon_block_sz;
+  uintx             _anon_classes_count;
+
+  ClassLoaderStats() :
+    _cld(0),
+    _class_loader(0),
+    _parent(0),
+    _chunk_sz(0),
+    _block_sz(0),
+    _classes_count(0),
+    _anon_block_sz(0),
+    _anon_chunk_sz(0),
+    _anon_classes_count(0) {
+  }
+};
+
+
+class ClassLoaderStatsClosure : public CLDClosure {
+protected:
+  static bool oop_equals(oop const& s1, oop const& s2) {
+    return s1 == s2;
+  }
+
+  static unsigned oop_hash(oop const& s1) {
+    unsigned hash = (unsigned)((uintptr_t)&s1);
+    return hash ^ (hash >> LogMinObjAlignment);
+  }
+
+  typedef ResourceHashtable<oop, ClassLoaderStats*,
+      ClassLoaderStatsClosure::oop_hash, ClassLoaderStatsClosure::oop_equals> StatsTable;
+
+  outputStream* _out;
+  StatsTable* _stats;
+  uintx   _total_loaders;
+  uintx   _total_classes;
+  size_t  _total_chunk_sz;
+  size_t  _total_block_sz;
+
+public:
+  ClassLoaderStatsClosure(outputStream* out) :
+    _out(out),
+    _total_loaders(0),
+    _total_block_sz(0),
+    _total_chunk_sz(0),
+    _total_classes(0),
+    _stats(new StatsTable()) {
+  }
+
+  virtual void do_cld(ClassLoaderData* cld);
+  virtual bool do_entry(oop const& key, ClassLoaderStats* const& cls);
+  void print();
+
+private:
+  void addEmptyParents(oop cl);
+};
+
+
+class ClassLoaderStatsVMOperation : public VM_Operation {
+  outputStream* _out;
+
+public:
+  ClassLoaderStatsVMOperation(outputStream* out) :
+    _out(out) {
+  }
+
+  VMOp_Type type() const {
+    return VMOp_ClassLoaderStatsOperation;
+  }
+
+  void doit();
+};
+
+#endif // SHARE_VM_CLASSFILE_CLASSLOADERSTATS_HPP

src/share/vm/memory/metaspace.cpp

 /*
- * Copyright (c) 2011, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -154,7 +154,7 @@ class ChunkManager : public CHeapObj<mtInternal> {
 
   // Map a size to a list index assuming that there are lists
   // for special, small, medium, and humongous chunks.
-  static ChunkIndex list_index(size_t size);
+  ChunkIndex list_index(size_t size);
 
   // Remove the chunk from its freelist.  It is
   // expected to be on one of the _free_chunks[] lists.
@@ -706,6 +706,7 @@ class SpaceManager : public CHeapObj<mtClass> {
   size_t allocated_blocks_words() const { return _allocated_blocks_words; }
   size_t allocated_blocks_bytes() const { return _allocated_blocks_words * BytesPerWord; }
   size_t allocated_chunks_words() const { return _allocated_chunks_words; }
+  size_t allocated_chunks_bytes() const { return _allocated_chunks_words * BytesPerWord; }
   size_t allocated_chunks_count() const { return _allocated_chunks_count; }
 
   bool is_humongous(size_t word_size) { return word_size > medium_chunk_size(); }
@@ -1751,7 +1752,11 @@ void ChunkManager::locked_print_sum_free_chunks(outputStream* st) {
   st->print_cr("Sum free chunk total " SIZE_FORMAT "  count " SIZE_FORMAT,
                 sum_free_chunks(), sum_free_chunks_count());
 }
+
 ChunkList* ChunkManager::free_chunks(ChunkIndex index) {
+  assert(index == SpecializedIndex || index == SmallIndex || index == MediumIndex,
+         err_msg("Bad index: %d", (int)index));
+
   return &_free_chunks[index];
 }
 
@@ -1863,7 +1868,7 @@ Metachunk* ChunkManager::chunk_freelist_allocate(size_t word_size) {
   }
 
   assert((word_size <= chunk->word_size()) ||
-         list_index(chunk->word_size() == HumongousIndex),
+         (list_index(chunk->word_size()) == HumongousIndex),
          "Non-humongous variable sized chunk");
   if (TraceMetadataChunkAllocation) {
     size_t list_count;
@@ -2357,22 +2362,18 @@ const char* SpaceManager::chunk_size_name(ChunkIndex index) const {
 }
 
 ChunkIndex ChunkManager::list_index(size_t size) {
-  switch (size) {
-    case SpecializedChunk:
-      assert(SpecializedChunk == ClassSpecializedChunk,
-             "Need branch for ClassSpecializedChunk");
+  if (free_chunks(SpecializedIndex)->size() == size) {
     return SpecializedIndex;
-    case SmallChunk:
-    case ClassSmallChunk:
+  }
+  if (free_chunks(SmallIndex)->size() == size) {
     return SmallIndex;
-    case MediumChunk:
-    case ClassMediumChunk:
+  }
+  if (free_chunks(MediumIndex)->size() == size) {
     return MediumIndex;
-    default:
-      assert(size > MediumChunk || size > ClassMediumChunk,
-             "Not a humongous chunk");
-      return HumongousIndex;
   }
+
+  assert(size > free_chunks(MediumIndex)->size(), "Not a humongous chunk");
+  return HumongousIndex;
 }
 
 void SpaceManager::deallocate(MetaWord* p, size_t word_size) {
@@ -2394,7 +2395,7 @@ void SpaceManager::add_chunk(Metachunk* new_chunk, bool make_current) {
 
   // Find the correct list and and set the current
   // chunk for that list.
-  ChunkIndex index = ChunkManager::list_index(new_chunk->word_size());
+  ChunkIndex index = chunk_manager()->list_index(new_chunk->word_size());
 
   if (index != HumongousIndex) {
     retire_current_chunk();
@@ -3463,6 +3464,16 @@ size_t Metaspace::capacity_bytes_slow(MetadataType mdtype) const {
   return capacity_words_slow(mdtype) * BytesPerWord;
 }
 
+size_t Metaspace::allocated_blocks_bytes() const {
+  return vsm()->allocated_blocks_bytes() +
+      (using_class_space() ? class_vsm()->allocated_blocks_bytes() : 0);
+}
+
+size_t Metaspace::allocated_chunks_bytes() const {
+  return vsm()->allocated_chunks_bytes() +
+      (using_class_space() ? class_vsm()->allocated_chunks_bytes() : 0);
+}
+
 void Metaspace::deallocate(MetaWord* ptr, size_t word_size, bool is_class) {
   if (SafepointSynchronize::is_at_safepoint()) {
     if (DumpSharedSpaces && PrintSharedSpaces) {
@@ -4020,4 +4031,40 @@ void SpaceManager_test_adjust_initial_chunk_size() {
   SpaceManagerTest::test_adjust_initial_chunk_size();
 }
 
+// The following test is placed here instead of a gtest / unittest file
+// because the ChunkManager class is only available in this file.
+void ChunkManager_test_list_index() {
+  ChunkManager manager(ClassSpecializedChunk, ClassSmallChunk, ClassMediumChunk);
+
+  // Test previous bug where a query for a humongous class metachunk,
+  // incorrectly matched the non-class medium metachunk size.
+  {
+    assert(MediumChunk > ClassMediumChunk, "Precondition for test");
+
+    ChunkIndex index = manager.list_index(MediumChunk);
+
+    assert(index == HumongousIndex,
+           err_msg("Requested size is larger than ClassMediumChunk,"
+           " so should return HumongousIndex. Got index: %d", (int)index));
+  }
+
+  // Check the specified sizes as well.
+  {
+    ChunkIndex index = manager.list_index(ClassSpecializedChunk);
+    assert(index == SpecializedIndex, err_msg("Wrong index returned. Got index: %d", (int)index));
+  }
+  {
+    ChunkIndex index = manager.list_index(ClassSmallChunk);
+    assert(index == SmallIndex, err_msg("Wrong index returned. Got index: %d", (int)index));
+  }
+  {
+    ChunkIndex index = manager.list_index(ClassMediumChunk);
+    assert(index == MediumIndex, err_msg("Wrong index returned. Got index: %d", (int)index));
+  }
+  {
+    ChunkIndex index = manager.list_index(ClassMediumChunk + 1);
+    assert(index == HumongousIndex, err_msg("Wrong index returned. Got index: %d", (int)index));
+  }
+}
+
 #endif

src/share/vm/memory/metaspace.hpp

@@ -232,6 +232,9 @@ class Metaspace : public CHeapObj<mtClass> {
   size_t used_bytes_slow(MetadataType mdtype) const;
   size_t capacity_bytes_slow(MetadataType mdtype) const;
 
+  size_t allocated_blocks_bytes() const;
+  size_t allocated_chunks_bytes() const;
+
   static MetaWord* allocate(ClassLoaderData* loader_data, size_t word_size,
                             bool read_only, MetaspaceObj::Type type, TRAPS);
   void deallocate(MetaWord* ptr, size_t byte_size, bool is_class);

src/share/vm/prims/jni.cpp

 /*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2012 Red Hat, Inc.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -5106,6 +5106,7 @@ void TestG1BiasedArray_test();
 void TestBufferingOopClosure_test();
 void TestCodeCacheRemSet_test();
 void FreeRegionList_test();
+void ChunkManager_test_list_index();
 #endif
 
 void execute_internal_vm_tests() {
@@ -5139,6 +5140,7 @@ void execute_internal_vm_tests() {
     run_unit_test(TestG1BiasedArray_test());
     run_unit_test(HeapRegionRemSet::test_prt());
     run_unit_test(SpaceManager_test_adjust_initial_chunk_size());
+    run_unit_test(ChunkManager_test_list_index());
     run_unit_test(TestBufferingOopClosure_test());
     run_unit_test(TestCodeCacheRemSet_test());
     if (UseG1GC) {

src/share/vm/runtime/vm_operations.hpp

@@ -97,6 +97,7 @@
   template(LinuxDllLoad)                          \
   template(RotateGCLog)                           \
   template(WhiteBoxOperation)                     \
+  template(ClassLoaderStatsOperation)             \
 
 class VM_Operation: public CHeapObj<mtInternal> {
  public:

src/share/vm/services/diagnosticCommand.cpp

@@ -23,6 +23,7 @@
  */
 
 #include "precompiled.hpp"
+#include "classfile/classLoaderStats.hpp"
 #include "gc_implementation/shared/vmGCOperations.hpp"
 #include "runtime/javaCalls.hpp"
 #include "runtime/os.hpp"
@@ -61,6 +62,7 @@ void DCmdRegistrant::register_dcmds(){
 #endif // INCLUDE_SERVICES
   DCmdFactory::register_DCmdFactory(new DCmdFactoryImpl<ThreadDumpDCmd>(full_export, true, false));
   DCmdFactory::register_DCmdFactory(new DCmdFactoryImpl<RotateGCLogDCmd>(full_export, true, false));
+  DCmdFactory::register_DCmdFactory(new DCmdFactoryImpl<ClassLoaderStatsDCmd>(full_export, true, false));
 
   // Enhanced JMX Agent Support
   // These commands won't be exported via the DiagnosticCommandMBean until an

test/serviceability/dcmd/ClassLoaderStatsTest.java

+/*
+ * Copyright (c) 2014, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ *
+ * @build ClassLoaderStatsTest DcmdUtil
+ * @run main ClassLoaderStatsTest
+ */
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.StringReader;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class ClassLoaderStatsTest {
+
+    // ClassLoader         Parent              CLD*               Classes   ChunkSz   BlockSz  Type
+    // 0x00000007c0215928  0x0000000000000000  0x0000000000000000       0         0         0  org.eclipse.osgi.baseadaptor.BaseAdaptor$1
+    // 0x00000007c0009868  0x0000000000000000  0x00007fc52aebcc80       1      6144      3768  sun.reflect.DelegatingClassLoader
+    // 0x00000007c0009868  0x0000000000000000  0x00007fc52b8916d0       1      6144      3688  sun.reflect.DelegatingClassLoader
+    // 0x00000007c0009868  0x00000007c0038ba8  0x00007fc52afb8760       1      6144      3688  sun.reflect.DelegatingClassLoader
+    // 0x00000007c0009868  0x0000000000000000  0x00007fc52afbb1a0       1      6144      3688  sun.reflect.DelegatingClassLoader
+    // 0x0000000000000000  0x0000000000000000  0x00007fc523416070    5019  30060544  29956216  <boot classloader>
+    //                                                                455   1210368    672848   + unsafe anonymous classes
+    // 0x00000007c016b5c8  0x00000007c0038ba8  0x00007fc52a995000       5      8192      5864  org.netbeans.StandardModule$OneModuleClassLoader
+    // 0x00000007c0009868  0x00000007c016b5c8  0x00007fc52ac13640       1      6144      3896  sun.reflect.DelegatingClassLoader
+    // ...
+
+    static Pattern clLine = Pattern.compile("0x\\p{XDigit}*\\s*0x\\p{XDigit}*\\s*0x\\p{XDigit}*\\s*(\\d*)\\s*(\\d*)\\s*(\\d*)\\s*(.*)");
+    static Pattern anonLine = Pattern.compile("\\s*(\\d*)\\s*(\\d*)\\s*(\\d*)\\s*.*");
+
+    public static DummyClassLoader dummyloader;
+
+    public static void main(String arg[]) throws Exception {
+
+        // create a classloader and load our special class
+        dummyloader = new DummyClassLoader();
+        Class<?> c = Class.forName("TestClass", true, dummyloader);
+        if (c.getClassLoader() != dummyloader) {
+            throw new RuntimeException("TestClass defined by wrong classloader: " + c.getClassLoader());
+        }
+
+        String result = DcmdUtil.executeDcmd("VM.classloader_stats");
+        BufferedReader r = new BufferedReader(new StringReader(result));
+        String line;
+        while((line = r.readLine()) != null) {
+            Matcher m = clLine.matcher(line);
+            if (m.matches()) {
+                // verify that DummyClassLoader has loaded 1 class and 1 anonymous class
+                if (m.group(4).equals("ClassLoaderStatsTest$DummyClassLoader")) {
+                    System.out.println("line: " + line);
+                    if (!m.group(1).equals("1")) {
+                        throw new Exception("Should have loaded 1 class: " + line);
+                    }
+                    checkPositiveInt(m.group(2));
+                    checkPositiveInt(m.group(3));
+
+                    String next = r.readLine();
+                    System.out.println("next: " + next);
+                    Matcher m1 = anonLine.matcher(next);
+                    m1.matches();
+                    if (!m1.group(1).equals("1")) {
+                        throw new Exception("Should have loaded 1 anonymous class, but found : " + m1.group(1));
+                    }
+                    checkPositiveInt(m1.group(2));
+                    checkPositiveInt(m1.group(3));
+                }
+            }
+        }
+    }
+
+    private static void checkPositiveInt(String s) throws Exception {
+        if (Integer.parseInt(s) <= 0) {
+            throw new Exception("Value should have been > 0: " + s);
+        }
+    }
+
+    public static class DummyClassLoader extends ClassLoader {
+
+        public static final String CLASS_NAME = "TestClass";
+
+        static ByteBuffer readClassFile(String name)
+        {
+            File f = new File(System.getProperty("test.classes", "."),
+                              name);
+            try (FileInputStream fin = new FileInputStream(f);
+                 FileChannel fc = fin.getChannel())
+            {
+                return fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size());
+            } catch (IOException e) {
+                throw new RuntimeException("Can't open file: " + name, e);
+            }
+        }
+
+        protected Class<?> loadClass(String name, boolean resolve)
+            throws ClassNotFoundException
+        {
+            Class<?> c;
+            if (!"TestClass".equals(name)) {
+                c = super.loadClass(name, resolve);
+            } else {
+                // should not delegate to the system class loader
+                c = findClass(name);
+                if (resolve) {
+                    resolveClass(c);
+                }
+            }
+            return c;
+        }
+
+        protected Class<?> findClass(String name)
+            throws ClassNotFoundException
+        {
+            if (!"TestClass".equals(name)) {
+                throw new ClassNotFoundException("Unexpected class: " + name);
+            }
+            return defineClass(name, readClassFile(name + ".class"), null);
+        }
+    } /* DummyClassLoader */
+
+}
+
+class TestClass {
+    static {
+        // force creation of anonymous class (for the lambdaform)
+        Runnable r = () -> System.out.println("Hello");
+        r.run();
+    }
+}