src/hotspot/share/services/heapDumper.cpp
changeset 47216 71c04702a3d5
parent 46968 9119841280f4
child 47532 d8e417df3468
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/services/heapDumper.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,2068 @@
+/*
+ * Copyright (c) 2005, 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/symbolTable.hpp"
+#include "classfile/systemDictionary.hpp"
+#include "classfile/vmSymbols.hpp"
+#include "gc/shared/gcLocker.inline.hpp"
+#include "gc/shared/genCollectedHeap.hpp"
+#include "gc/shared/vmGCOperations.hpp"
+#include "memory/resourceArea.hpp"
+#include "memory/universe.hpp"
+#include "oops/objArrayKlass.hpp"
+#include "oops/objArrayOop.inline.hpp"
+#include "oops/oop.inline.hpp"
+#include "prims/jvm.h"
+#include "runtime/javaCalls.hpp"
+#include "runtime/jniHandles.hpp"
+#include "runtime/os.hpp"
+#include "runtime/reflectionUtils.hpp"
+#include "runtime/vframe.hpp"
+#include "runtime/vmThread.hpp"
+#include "runtime/vm_operations.hpp"
+#include "services/heapDumper.hpp"
+#include "services/threadService.hpp"
+#include "utilities/macros.hpp"
+#include "utilities/ostream.hpp"
+#if INCLUDE_ALL_GCS
+#include "gc/parallel/parallelScavengeHeap.hpp"
+#endif // INCLUDE_ALL_GCS
+
+/*
+ * HPROF binary format - description copied from:
+ *   src/share/demo/jvmti/hprof/hprof_io.c
+ *
+ *
+ *  header    "JAVA PROFILE 1.0.2" (0-terminated)
+ *
+ *  u4        size of identifiers. Identifiers are used to represent
+ *            UTF8 strings, objects, stack traces, etc. They usually
+ *            have the same size as host pointers. For example, on
+ *            Solaris and Win32, the size is 4.
+ * u4         high word
+ * u4         low word    number of milliseconds since 0:00 GMT, 1/1/70
+ * [record]*  a sequence of records.
+ *
+ *
+ * Record format:
+ *
+ * u1         a TAG denoting the type of the record
+ * u4         number of *microseconds* since the time stamp in the
+ *            header. (wraps around in a little more than an hour)
+ * u4         number of bytes *remaining* in the record. Note that
+ *            this number excludes the tag and the length field itself.
+ * [u1]*      BODY of the record (a sequence of bytes)
+ *
+ *
+ * The following TAGs are supported:
+ *
+ * TAG           BODY       notes
+ *----------------------------------------------------------
+ * HPROF_UTF8               a UTF8-encoded name
+ *
+ *               id         name ID
+ *               [u1]*      UTF8 characters (no trailing zero)
+ *
+ * HPROF_LOAD_CLASS         a newly loaded class
+ *
+ *                u4        class serial number (> 0)
+ *                id        class object ID
+ *                u4        stack trace serial number
+ *                id        class name ID
+ *
+ * HPROF_UNLOAD_CLASS       an unloading class
+ *
+ *                u4        class serial_number
+ *
+ * HPROF_FRAME              a Java stack frame
+ *
+ *                id        stack frame ID
+ *                id        method name ID
+ *                id        method signature ID
+ *                id        source file name ID
+ *                u4        class serial number
+ *                i4        line number. >0: normal
+ *                                       -1: unknown
+ *                                       -2: compiled method
+ *                                       -3: native method
+ *
+ * HPROF_TRACE              a Java stack trace
+ *
+ *               u4         stack trace serial number
+ *               u4         thread serial number
+ *               u4         number of frames
+ *               [id]*      stack frame IDs
+ *
+ *
+ * HPROF_ALLOC_SITES        a set of heap allocation sites, obtained after GC
+ *
+ *               u2         flags 0x0001: incremental vs. complete
+ *                                0x0002: sorted by allocation vs. live
+ *                                0x0004: whether to force a GC
+ *               u4         cutoff ratio
+ *               u4         total live bytes
+ *               u4         total live instances
+ *               u8         total bytes allocated
+ *               u8         total instances allocated
+ *               u4         number of sites that follow
+ *               [u1        is_array: 0:  normal object
+ *                                    2:  object array
+ *                                    4:  boolean array
+ *                                    5:  char array
+ *                                    6:  float array
+ *                                    7:  double array
+ *                                    8:  byte array
+ *                                    9:  short array
+ *                                    10: int array
+ *                                    11: long array
+ *                u4        class serial number (may be zero during startup)
+ *                u4        stack trace serial number
+ *                u4        number of bytes alive
+ *                u4        number of instances alive
+ *                u4        number of bytes allocated
+ *                u4]*      number of instance allocated
+ *
+ * HPROF_START_THREAD       a newly started thread.
+ *
+ *               u4         thread serial number (> 0)
+ *               id         thread object ID
+ *               u4         stack trace serial number
+ *               id         thread name ID
+ *               id         thread group name ID
+ *               id         thread group parent name ID
+ *
+ * HPROF_END_THREAD         a terminating thread.
+ *
+ *               u4         thread serial number
+ *
+ * HPROF_HEAP_SUMMARY       heap summary
+ *
+ *               u4         total live bytes
+ *               u4         total live instances
+ *               u8         total bytes allocated
+ *               u8         total instances allocated
+ *
+ * HPROF_HEAP_DUMP          denote a heap dump
+ *
+ *               [heap dump sub-records]*
+ *
+ *                          There are four kinds of heap dump sub-records:
+ *
+ *               u1         sub-record type
+ *
+ *               HPROF_GC_ROOT_UNKNOWN         unknown root
+ *
+ *                          id         object ID
+ *
+ *               HPROF_GC_ROOT_THREAD_OBJ      thread object
+ *
+ *                          id         thread object ID  (may be 0 for a
+ *                                     thread newly attached through JNI)
+ *                          u4         thread sequence number
+ *                          u4         stack trace sequence number
+ *
+ *               HPROF_GC_ROOT_JNI_GLOBAL      JNI global ref root
+ *
+ *                          id         object ID
+ *                          id         JNI global ref ID
+ *
+ *               HPROF_GC_ROOT_JNI_LOCAL       JNI local ref
+ *
+ *                          id         object ID
+ *                          u4         thread serial number
+ *                          u4         frame # in stack trace (-1 for empty)
+ *
+ *               HPROF_GC_ROOT_JAVA_FRAME      Java stack frame
+ *
+ *                          id         object ID
+ *                          u4         thread serial number
+ *                          u4         frame # in stack trace (-1 for empty)
+ *
+ *               HPROF_GC_ROOT_NATIVE_STACK    Native stack
+ *
+ *                          id         object ID
+ *                          u4         thread serial number
+ *
+ *               HPROF_GC_ROOT_STICKY_CLASS    System class
+ *
+ *                          id         object ID
+ *
+ *               HPROF_GC_ROOT_THREAD_BLOCK    Reference from thread block
+ *
+ *                          id         object ID
+ *                          u4         thread serial number
+ *
+ *               HPROF_GC_ROOT_MONITOR_USED    Busy monitor
+ *
+ *                          id         object ID
+ *
+ *               HPROF_GC_CLASS_DUMP           dump of a class object
+ *
+ *                          id         class object ID
+ *                          u4         stack trace serial number
+ *                          id         super class object ID
+ *                          id         class loader object ID
+ *                          id         signers object ID
+ *                          id         protection domain object ID
+ *                          id         reserved
+ *                          id         reserved
+ *
+ *                          u4         instance size (in bytes)
+ *
+ *                          u2         size of constant pool
+ *                          [u2,       constant pool index,
+ *                           ty,       type
+ *                                     2:  object
+ *                                     4:  boolean
+ *                                     5:  char
+ *                                     6:  float
+ *                                     7:  double
+ *                                     8:  byte
+ *                                     9:  short
+ *                                     10: int
+ *                                     11: long
+ *                           vl]*      and value
+ *
+ *                          u2         number of static fields
+ *                          [id,       static field name,
+ *                           ty,       type,
+ *                           vl]*      and value
+ *
+ *                          u2         number of inst. fields (not inc. super)
+ *                          [id,       instance field name,
+ *                           ty]*      type
+ *
+ *               HPROF_GC_INSTANCE_DUMP        dump of a normal object
+ *
+ *                          id         object ID
+ *                          u4         stack trace serial number
+ *                          id         class object ID
+ *                          u4         number of bytes that follow
+ *                          [vl]*      instance field values (class, followed
+ *                                     by super, super's super ...)
+ *
+ *               HPROF_GC_OBJ_ARRAY_DUMP       dump of an object array
+ *
+ *                          id         array object ID
+ *                          u4         stack trace serial number
+ *                          u4         number of elements
+ *                          id         array class ID
+ *                          [id]*      elements
+ *
+ *               HPROF_GC_PRIM_ARRAY_DUMP      dump of a primitive array
+ *
+ *                          id         array object ID
+ *                          u4         stack trace serial number
+ *                          u4         number of elements
+ *                          u1         element type
+ *                                     4:  boolean array
+ *                                     5:  char array
+ *                                     6:  float array
+ *                                     7:  double array
+ *                                     8:  byte array
+ *                                     9:  short array
+ *                                     10: int array
+ *                                     11: long array
+ *                          [u1]*      elements
+ *
+ * HPROF_CPU_SAMPLES        a set of sample traces of running threads
+ *
+ *                u4        total number of samples
+ *                u4        # of traces
+ *               [u4        # of samples
+ *                u4]*      stack trace serial number
+ *
+ * HPROF_CONTROL_SETTINGS   the settings of on/off switches
+ *
+ *                u4        0x00000001: alloc traces on/off
+ *                          0x00000002: cpu sampling on/off
+ *                u2        stack trace depth
+ *
+ *
+ * When the header is "JAVA PROFILE 1.0.2" a heap dump can optionally
+ * be generated as a sequence of heap dump segments. This sequence is
+ * terminated by an end record. The additional tags allowed by format
+ * "JAVA PROFILE 1.0.2" are:
+ *
+ * HPROF_HEAP_DUMP_SEGMENT  denote a heap dump segment
+ *
+ *               [heap dump sub-records]*
+ *               The same sub-record types allowed by HPROF_HEAP_DUMP
+ *
+ * HPROF_HEAP_DUMP_END      denotes the end of a heap dump
+ *
+ */
+
+
+// HPROF tags
+
+typedef enum {
+  // top-level records
+  HPROF_UTF8                    = 0x01,
+  HPROF_LOAD_CLASS              = 0x02,
+  HPROF_UNLOAD_CLASS            = 0x03,
+  HPROF_FRAME                   = 0x04,
+  HPROF_TRACE                   = 0x05,
+  HPROF_ALLOC_SITES             = 0x06,
+  HPROF_HEAP_SUMMARY            = 0x07,
+  HPROF_START_THREAD            = 0x0A,
+  HPROF_END_THREAD              = 0x0B,
+  HPROF_HEAP_DUMP               = 0x0C,
+  HPROF_CPU_SAMPLES             = 0x0D,
+  HPROF_CONTROL_SETTINGS        = 0x0E,
+
+  // 1.0.2 record types
+  HPROF_HEAP_DUMP_SEGMENT       = 0x1C,
+  HPROF_HEAP_DUMP_END           = 0x2C,
+
+  // field types
+  HPROF_ARRAY_OBJECT            = 0x01,
+  HPROF_NORMAL_OBJECT           = 0x02,
+  HPROF_BOOLEAN                 = 0x04,
+  HPROF_CHAR                    = 0x05,
+  HPROF_FLOAT                   = 0x06,
+  HPROF_DOUBLE                  = 0x07,
+  HPROF_BYTE                    = 0x08,
+  HPROF_SHORT                   = 0x09,
+  HPROF_INT                     = 0x0A,
+  HPROF_LONG                    = 0x0B,
+
+  // data-dump sub-records
+  HPROF_GC_ROOT_UNKNOWN         = 0xFF,
+  HPROF_GC_ROOT_JNI_GLOBAL      = 0x01,
+  HPROF_GC_ROOT_JNI_LOCAL       = 0x02,
+  HPROF_GC_ROOT_JAVA_FRAME      = 0x03,
+  HPROF_GC_ROOT_NATIVE_STACK    = 0x04,
+  HPROF_GC_ROOT_STICKY_CLASS    = 0x05,
+  HPROF_GC_ROOT_THREAD_BLOCK    = 0x06,
+  HPROF_GC_ROOT_MONITOR_USED    = 0x07,
+  HPROF_GC_ROOT_THREAD_OBJ      = 0x08,
+  HPROF_GC_CLASS_DUMP           = 0x20,
+  HPROF_GC_INSTANCE_DUMP        = 0x21,
+  HPROF_GC_OBJ_ARRAY_DUMP       = 0x22,
+  HPROF_GC_PRIM_ARRAY_DUMP      = 0x23
+} hprofTag;
+
+// Default stack trace ID (used for dummy HPROF_TRACE record)
+enum {
+  STACK_TRACE_ID = 1,
+  INITIAL_CLASS_COUNT = 200
+};
+
+// Supports I/O operations on a dump file
+
+class DumpWriter : public StackObj {
+ private:
+  enum {
+    io_buffer_size  = 8*M
+  };
+
+  int _fd;              // file descriptor (-1 if dump file not open)
+  julong _bytes_written; // number of byte written to dump file
+
+  char* _buffer;    // internal buffer
+  size_t _size;
+  size_t _pos;
+
+  jlong _dump_start;
+
+  char* _error;   // error message when I/O fails
+
+  void set_file_descriptor(int fd)              { _fd = fd; }
+  int file_descriptor() const                   { return _fd; }
+
+  char* buffer() const                          { return _buffer; }
+  size_t buffer_size() const                    { return _size; }
+  size_t position() const                       { return _pos; }
+  void set_position(size_t pos)                 { _pos = pos; }
+
+  void set_error(const char* error)             { _error = (char*)os::strdup(error); }
+
+  // all I/O go through this function
+  void write_internal(void* s, size_t len);
+
+ public:
+  DumpWriter(const char* path);
+  ~DumpWriter();
+
+  void close();
+  bool is_open() const                  { return file_descriptor() >= 0; }
+  void flush();
+
+  jlong dump_start() const                      { return _dump_start; }
+  void set_dump_start(jlong pos);
+  julong current_record_length();
+
+  // total number of bytes written to the disk
+  julong bytes_written() const          { return _bytes_written; }
+
+  // adjust the number of bytes written to disk (used to keep the count
+  // of the number of bytes written in case of rewrites)
+  void adjust_bytes_written(jlong n)    { _bytes_written += n; }
+
+  // number of (buffered) bytes as yet unwritten to the dump file
+  size_t bytes_unwritten() const        { return position(); }
+
+  char* error() const                   { return _error; }
+
+  jlong current_offset();
+  void seek_to_offset(jlong pos);
+
+  // writer functions
+  void write_raw(void* s, size_t len);
+  void write_u1(u1 x)                   { write_raw((void*)&x, 1); }
+  void write_u2(u2 x);
+  void write_u4(u4 x);
+  void write_u8(u8 x);
+  void write_objectID(oop o);
+  void write_symbolID(Symbol* o);
+  void write_classID(Klass* k);
+  void write_id(u4 x);
+};
+
+DumpWriter::DumpWriter(const char* path) {
+  // try to allocate an I/O buffer of io_buffer_size. If there isn't
+  // sufficient memory then reduce size until we can allocate something.
+  _size = io_buffer_size;
+  do {
+    _buffer = (char*)os::malloc(_size, mtInternal);
+    if (_buffer == NULL) {
+      _size = _size >> 1;
+    }
+  } while (_buffer == NULL && _size > 0);
+  assert((_size > 0 && _buffer != NULL) || (_size == 0 && _buffer == NULL), "sanity check");
+  _pos = 0;
+  _error = NULL;
+  _bytes_written = 0L;
+  _dump_start = (jlong)-1;
+  _fd = os::create_binary_file(path, false);    // don't replace existing file
+
+  // if the open failed we record the error
+  if (_fd < 0) {
+    _error = (char*)os::strdup(os::strerror(errno));
+  }
+}
+
+DumpWriter::~DumpWriter() {
+  // flush and close dump file
+  if (is_open()) {
+    close();
+  }
+  if (_buffer != NULL) os::free(_buffer);
+  if (_error != NULL) os::free(_error);
+}
+
+// closes dump file (if open)
+void DumpWriter::close() {
+  // flush and close dump file
+  if (is_open()) {
+    flush();
+    os::close(file_descriptor());
+    set_file_descriptor(-1);
+  }
+}
+
+// sets the dump starting position
+void DumpWriter::set_dump_start(jlong pos) {
+  _dump_start = pos;
+}
+
+julong DumpWriter::current_record_length() {
+  if (is_open()) {
+    // calculate the size of the dump record
+    julong dump_end = bytes_written() + bytes_unwritten();
+    assert(dump_end == (size_t)current_offset(), "checking");
+    julong dump_len = dump_end - dump_start() - 4;
+    return dump_len;
+  }
+  return 0;
+}
+
+// write directly to the file
+void DumpWriter::write_internal(void* s, size_t len) {
+  if (is_open()) {
+    const char* pos = (char*)s;
+    ssize_t n = 0;
+    while (len > 0) {
+      uint tmp = (uint)MIN2(len, (size_t)UINT_MAX);
+      n = os::write(file_descriptor(), pos, tmp);
+
+      if (n < 0) {
+        // EINTR cannot happen here, os::write will take care of that
+        set_error(os::strerror(errno));
+        os::close(file_descriptor());
+        set_file_descriptor(-1);
+        return;
+      }
+
+      _bytes_written += n;
+      pos += n;
+      len -= n;
+    }
+  }
+}
+
+// write raw bytes
+void DumpWriter::write_raw(void* s, size_t len) {
+  if (is_open()) {
+    // flush buffer to make room
+    if ((position() + len) >= buffer_size()) {
+      flush();
+    }
+
+    // buffer not available or too big to buffer it
+    if ((buffer() == NULL) || (len >= buffer_size())) {
+      write_internal(s, len);
+    } else {
+      // Should optimize this for u1/u2/u4/u8 sizes.
+      memcpy(buffer() + position(), s, len);
+      set_position(position() + len);
+    }
+  }
+}
+
+// flush any buffered bytes to the file
+void DumpWriter::flush() {
+  if (is_open() && position() > 0) {
+    write_internal(buffer(), position());
+    set_position(0);
+  }
+}
+
+jlong DumpWriter::current_offset() {
+  if (is_open()) {
+    // the offset is the file offset plus whatever we have buffered
+    jlong offset = os::current_file_offset(file_descriptor());
+    assert(offset >= 0, "lseek failed");
+    return offset + position();
+  } else {
+    return (jlong)-1;
+  }
+}
+
+void DumpWriter::seek_to_offset(jlong off) {
+  assert(off >= 0, "bad offset");
+
+  // need to flush before seeking
+  flush();
+
+  // may be closed due to I/O error
+  if (is_open()) {
+    jlong n = os::seek_to_file_offset(file_descriptor(), off);
+    assert(n >= 0, "lseek failed");
+  }
+}
+
+void DumpWriter::write_u2(u2 x) {
+  u2 v;
+  Bytes::put_Java_u2((address)&v, x);
+  write_raw((void*)&v, 2);
+}
+
+void DumpWriter::write_u4(u4 x) {
+  u4 v;
+  Bytes::put_Java_u4((address)&v, x);
+  write_raw((void*)&v, 4);
+}
+
+void DumpWriter::write_u8(u8 x) {
+  u8 v;
+  Bytes::put_Java_u8((address)&v, x);
+  write_raw((void*)&v, 8);
+}
+
+void DumpWriter::write_objectID(oop o) {
+  address a = (address)o;
+#ifdef _LP64
+  write_u8((u8)a);
+#else
+  write_u4((u4)a);
+#endif
+}
+
+void DumpWriter::write_symbolID(Symbol* s) {
+  address a = (address)((uintptr_t)s);
+#ifdef _LP64
+  write_u8((u8)a);
+#else
+  write_u4((u4)a);
+#endif
+}
+
+void DumpWriter::write_id(u4 x) {
+#ifdef _LP64
+  write_u8((u8) x);
+#else
+  write_u4(x);
+#endif
+}
+
+// We use java mirror as the class ID
+void DumpWriter::write_classID(Klass* k) {
+  write_objectID(k->java_mirror());
+}
+
+
+
+// Support class with a collection of functions used when dumping the heap
+
+class DumperSupport : AllStatic {
+ public:
+
+  // write a header of the given type
+  static void write_header(DumpWriter* writer, hprofTag tag, u4 len);
+
+  // returns hprof tag for the given type signature
+  static hprofTag sig2tag(Symbol* sig);
+  // returns hprof tag for the given basic type
+  static hprofTag type2tag(BasicType type);
+
+  // returns the size of the instance of the given class
+  static u4 instance_size(Klass* k);
+
+  // dump a jfloat
+  static void dump_float(DumpWriter* writer, jfloat f);
+  // dump a jdouble
+  static void dump_double(DumpWriter* writer, jdouble d);
+  // dumps the raw value of the given field
+  static void dump_field_value(DumpWriter* writer, char type, address addr);
+  // dumps static fields of the given class
+  static void dump_static_fields(DumpWriter* writer, Klass* k);
+  // dump the raw values of the instance fields of the given object
+  static void dump_instance_fields(DumpWriter* writer, oop o);
+  // dumps the definition of the instance fields for a given class
+  static void dump_instance_field_descriptors(DumpWriter* writer, Klass* k);
+  // creates HPROF_GC_INSTANCE_DUMP record for the given object
+  static void dump_instance(DumpWriter* writer, oop o);
+  // creates HPROF_GC_CLASS_DUMP record for the given class and each of its
+  // array classes
+  static void dump_class_and_array_classes(DumpWriter* writer, Klass* k);
+  // creates HPROF_GC_CLASS_DUMP record for a given primitive array
+  // class (and each multi-dimensional array class too)
+  static void dump_basic_type_array_class(DumpWriter* writer, Klass* k);
+
+  // creates HPROF_GC_OBJ_ARRAY_DUMP record for the given object array
+  static void dump_object_array(DumpWriter* writer, objArrayOop array);
+  // creates HPROF_GC_PRIM_ARRAY_DUMP record for the given type array
+  static void dump_prim_array(DumpWriter* writer, typeArrayOop array);
+  // create HPROF_FRAME record for the given method and bci
+  static void dump_stack_frame(DumpWriter* writer, int frame_serial_num, int class_serial_num, Method* m, int bci);
+
+  // check if we need to truncate an array
+  static int calculate_array_max_length(DumpWriter* writer, arrayOop array, short header_size);
+
+  // writes a HPROF_HEAP_DUMP_SEGMENT record
+  static void write_dump_header(DumpWriter* writer);
+
+  // fixes up the length of the current dump record
+  static void write_current_dump_record_length(DumpWriter* writer);
+
+  // fixes up the current dump record and writes HPROF_HEAP_DUMP_END record
+  static void end_of_dump(DumpWriter* writer);
+};
+
+// write a header of the given type
+void DumperSupport:: write_header(DumpWriter* writer, hprofTag tag, u4 len) {
+  writer->write_u1((u1)tag);
+  writer->write_u4(0);                  // current ticks
+  writer->write_u4(len);
+}
+
+// returns hprof tag for the given type signature
+hprofTag DumperSupport::sig2tag(Symbol* sig) {
+  switch (sig->byte_at(0)) {
+    case JVM_SIGNATURE_CLASS    : return HPROF_NORMAL_OBJECT;
+    case JVM_SIGNATURE_ARRAY    : return HPROF_NORMAL_OBJECT;
+    case JVM_SIGNATURE_BYTE     : return HPROF_BYTE;
+    case JVM_SIGNATURE_CHAR     : return HPROF_CHAR;
+    case JVM_SIGNATURE_FLOAT    : return HPROF_FLOAT;
+    case JVM_SIGNATURE_DOUBLE   : return HPROF_DOUBLE;
+    case JVM_SIGNATURE_INT      : return HPROF_INT;
+    case JVM_SIGNATURE_LONG     : return HPROF_LONG;
+    case JVM_SIGNATURE_SHORT    : return HPROF_SHORT;
+    case JVM_SIGNATURE_BOOLEAN  : return HPROF_BOOLEAN;
+    default : ShouldNotReachHere(); /* to shut up compiler */ return HPROF_BYTE;
+  }
+}
+
+hprofTag DumperSupport::type2tag(BasicType type) {
+  switch (type) {
+    case T_BYTE     : return HPROF_BYTE;
+    case T_CHAR     : return HPROF_CHAR;
+    case T_FLOAT    : return HPROF_FLOAT;
+    case T_DOUBLE   : return HPROF_DOUBLE;
+    case T_INT      : return HPROF_INT;
+    case T_LONG     : return HPROF_LONG;
+    case T_SHORT    : return HPROF_SHORT;
+    case T_BOOLEAN  : return HPROF_BOOLEAN;
+    default : ShouldNotReachHere(); /* to shut up compiler */ return HPROF_BYTE;
+  }
+}
+
+// dump a jfloat
+void DumperSupport::dump_float(DumpWriter* writer, jfloat f) {
+  if (g_isnan(f)) {
+    writer->write_u4(0x7fc00000);    // collapsing NaNs
+  } else {
+    union {
+      int i;
+      float f;
+    } u;
+    u.f = (float)f;
+    writer->write_u4((u4)u.i);
+  }
+}
+
+// dump a jdouble
+void DumperSupport::dump_double(DumpWriter* writer, jdouble d) {
+  union {
+    jlong l;
+    double d;
+  } u;
+  if (g_isnan(d)) {                 // collapsing NaNs
+    u.l = (jlong)(0x7ff80000);
+    u.l = (u.l << 32);
+  } else {
+    u.d = (double)d;
+  }
+  writer->write_u8((u8)u.l);
+}
+
+// dumps the raw value of the given field
+void DumperSupport::dump_field_value(DumpWriter* writer, char type, address addr) {
+  switch (type) {
+    case JVM_SIGNATURE_CLASS :
+    case JVM_SIGNATURE_ARRAY : {
+      oop o;
+      if (UseCompressedOops) {
+        o = oopDesc::load_decode_heap_oop((narrowOop*)addr);
+      } else {
+        o = oopDesc::load_decode_heap_oop((oop*)addr);
+      }
+
+      // reflection and Unsafe classes may have a reference to a
+      // Klass* so filter it out.
+      assert(oopDesc::is_oop_or_null(o), "Expected an oop or NULL at " PTR_FORMAT, p2i(o));
+      writer->write_objectID(o);
+      break;
+    }
+    case JVM_SIGNATURE_BYTE     : {
+      jbyte* b = (jbyte*)addr;
+      writer->write_u1((u1)*b);
+      break;
+    }
+    case JVM_SIGNATURE_CHAR     : {
+      jchar* c = (jchar*)addr;
+      writer->write_u2((u2)*c);
+      break;
+    }
+    case JVM_SIGNATURE_SHORT : {
+      jshort* s = (jshort*)addr;
+      writer->write_u2((u2)*s);
+      break;
+    }
+    case JVM_SIGNATURE_FLOAT : {
+      jfloat* f = (jfloat*)addr;
+      dump_float(writer, *f);
+      break;
+    }
+    case JVM_SIGNATURE_DOUBLE : {
+      jdouble* f = (jdouble*)addr;
+      dump_double(writer, *f);
+      break;
+    }
+    case JVM_SIGNATURE_INT : {
+      jint* i = (jint*)addr;
+      writer->write_u4((u4)*i);
+      break;
+    }
+    case JVM_SIGNATURE_LONG     : {
+      jlong* l = (jlong*)addr;
+      writer->write_u8((u8)*l);
+      break;
+    }
+    case JVM_SIGNATURE_BOOLEAN : {
+      jboolean* b = (jboolean*)addr;
+      writer->write_u1((u1)*b);
+      break;
+    }
+    default : ShouldNotReachHere();
+  }
+}
+
+// returns the size of the instance of the given class
+u4 DumperSupport::instance_size(Klass* k) {
+  HandleMark hm;
+  InstanceKlass* ik = InstanceKlass::cast(k);
+
+  u4 size = 0;
+
+  for (FieldStream fld(ik, false, false); !fld.eos(); fld.next()) {
+    if (!fld.access_flags().is_static()) {
+      Symbol* sig = fld.signature();
+      switch (sig->byte_at(0)) {
+        case JVM_SIGNATURE_CLASS   :
+        case JVM_SIGNATURE_ARRAY   : size += oopSize; break;
+
+        case JVM_SIGNATURE_BYTE    :
+        case JVM_SIGNATURE_BOOLEAN : size += 1; break;
+
+        case JVM_SIGNATURE_CHAR    :
+        case JVM_SIGNATURE_SHORT   : size += 2; break;
+
+        case JVM_SIGNATURE_INT     :
+        case JVM_SIGNATURE_FLOAT   : size += 4; break;
+
+        case JVM_SIGNATURE_LONG    :
+        case JVM_SIGNATURE_DOUBLE  : size += 8; break;
+
+        default : ShouldNotReachHere();
+      }
+    }
+  }
+  return size;
+}
+
+// dumps static fields of the given class
+void DumperSupport::dump_static_fields(DumpWriter* writer, Klass* k) {
+  HandleMark hm;
+  InstanceKlass* ik = InstanceKlass::cast(k);
+
+  // pass 1 - count the static fields
+  u2 field_count = 0;
+  for (FieldStream fldc(ik, true, true); !fldc.eos(); fldc.next()) {
+    if (fldc.access_flags().is_static()) field_count++;
+  }
+
+  writer->write_u2(field_count);
+
+  // pass 2 - dump the field descriptors and raw values
+  for (FieldStream fld(ik, true, true); !fld.eos(); fld.next()) {
+    if (fld.access_flags().is_static()) {
+      Symbol* sig = fld.signature();
+
+      writer->write_symbolID(fld.name());   // name
+      writer->write_u1(sig2tag(sig));       // type
+
+      // value
+      int offset = fld.offset();
+      address addr = (address)ik->java_mirror() + offset;
+
+      dump_field_value(writer, sig->byte_at(0), addr);
+    }
+  }
+}
+
+// dump the raw values of the instance fields of the given object
+void DumperSupport::dump_instance_fields(DumpWriter* writer, oop o) {
+  HandleMark hm;
+  InstanceKlass* ik = InstanceKlass::cast(o->klass());
+
+  for (FieldStream fld(ik, false, false); !fld.eos(); fld.next()) {
+    if (!fld.access_flags().is_static()) {
+      Symbol* sig = fld.signature();
+      address addr = (address)o + fld.offset();
+
+      dump_field_value(writer, sig->byte_at(0), addr);
+    }
+  }
+}
+
+// dumps the definition of the instance fields for a given class
+void DumperSupport::dump_instance_field_descriptors(DumpWriter* writer, Klass* k) {
+  HandleMark hm;
+  InstanceKlass* ik = InstanceKlass::cast(k);
+
+  // pass 1 - count the instance fields
+  u2 field_count = 0;
+  for (FieldStream fldc(ik, true, true); !fldc.eos(); fldc.next()) {
+    if (!fldc.access_flags().is_static()) field_count++;
+  }
+
+  writer->write_u2(field_count);
+
+  // pass 2 - dump the field descriptors
+  for (FieldStream fld(ik, true, true); !fld.eos(); fld.next()) {
+    if (!fld.access_flags().is_static()) {
+      Symbol* sig = fld.signature();
+
+      writer->write_symbolID(fld.name());                   // name
+      writer->write_u1(sig2tag(sig));       // type
+    }
+  }
+}
+
+// creates HPROF_GC_INSTANCE_DUMP record for the given object
+void DumperSupport::dump_instance(DumpWriter* writer, oop o) {
+  Klass* k = o->klass();
+
+  writer->write_u1(HPROF_GC_INSTANCE_DUMP);
+  writer->write_objectID(o);
+  writer->write_u4(STACK_TRACE_ID);
+
+  // class ID
+  writer->write_classID(k);
+
+  // number of bytes that follow
+  writer->write_u4(instance_size(k) );
+
+  // field values
+  dump_instance_fields(writer, o);
+}
+
+// creates HPROF_GC_CLASS_DUMP record for the given class and each of
+// its array classes
+void DumperSupport::dump_class_and_array_classes(DumpWriter* writer, Klass* k) {
+  InstanceKlass* ik = InstanceKlass::cast(k);
+
+  // We can safepoint and do a heap dump at a point where we have a Klass,
+  // but no java mirror class has been setup for it. So we need to check
+  // that the class is at least loaded, to avoid crash from a null mirror.
+  if (!ik->is_loaded()) {
+    return;
+  }
+
+  writer->write_u1(HPROF_GC_CLASS_DUMP);
+
+  // class ID
+  writer->write_classID(ik);
+  writer->write_u4(STACK_TRACE_ID);
+
+  // super class ID
+  Klass* java_super = ik->java_super();
+  if (java_super == NULL) {
+    writer->write_objectID(oop(NULL));
+  } else {
+    writer->write_classID(java_super);
+  }
+
+  writer->write_objectID(ik->class_loader());
+  writer->write_objectID(ik->signers());
+  writer->write_objectID(ik->protection_domain());
+
+  // reserved
+  writer->write_objectID(oop(NULL));
+  writer->write_objectID(oop(NULL));
+
+  // instance size
+  writer->write_u4(DumperSupport::instance_size(k));
+
+  // size of constant pool - ignored by HAT 1.1
+  writer->write_u2(0);
+
+  // number of static fields
+  dump_static_fields(writer, k);
+
+  // description of instance fields
+  dump_instance_field_descriptors(writer, k);
+
+  // array classes
+  k = k->array_klass_or_null();
+  while (k != NULL) {
+    Klass* klass = k;
+    assert(klass->is_objArray_klass(), "not an ObjArrayKlass");
+
+    writer->write_u1(HPROF_GC_CLASS_DUMP);
+    writer->write_classID(klass);
+    writer->write_u4(STACK_TRACE_ID);
+
+    // super class of array classes is java.lang.Object
+    java_super = klass->java_super();
+    assert(java_super != NULL, "checking");
+    writer->write_classID(java_super);
+
+    writer->write_objectID(ik->class_loader());
+    writer->write_objectID(ik->signers());
+    writer->write_objectID(ik->protection_domain());
+
+    writer->write_objectID(oop(NULL));    // reserved
+    writer->write_objectID(oop(NULL));
+    writer->write_u4(0);             // instance size
+    writer->write_u2(0);             // constant pool
+    writer->write_u2(0);             // static fields
+    writer->write_u2(0);             // instance fields
+
+    // get the array class for the next rank
+    k = klass->array_klass_or_null();
+  }
+}
+
+// creates HPROF_GC_CLASS_DUMP record for a given primitive array
+// class (and each multi-dimensional array class too)
+void DumperSupport::dump_basic_type_array_class(DumpWriter* writer, Klass* k) {
+ // array classes
+ while (k != NULL) {
+    Klass* klass = k;
+
+    writer->write_u1(HPROF_GC_CLASS_DUMP);
+    writer->write_classID(klass);
+    writer->write_u4(STACK_TRACE_ID);
+
+    // super class of array classes is java.lang.Object
+    Klass* java_super = klass->java_super();
+    assert(java_super != NULL, "checking");
+    writer->write_classID(java_super);
+
+    writer->write_objectID(oop(NULL));    // loader
+    writer->write_objectID(oop(NULL));    // signers
+    writer->write_objectID(oop(NULL));    // protection domain
+
+    writer->write_objectID(oop(NULL));    // reserved
+    writer->write_objectID(oop(NULL));
+    writer->write_u4(0);             // instance size
+    writer->write_u2(0);             // constant pool
+    writer->write_u2(0);             // static fields
+    writer->write_u2(0);             // instance fields
+
+    // get the array class for the next rank
+    k = klass->array_klass_or_null();
+  }
+}
+
+// Hprof uses an u4 as record length field,
+// which means we need to truncate arrays that are too long.
+int DumperSupport::calculate_array_max_length(DumpWriter* writer, arrayOop array, short header_size) {
+  BasicType type = ArrayKlass::cast(array->klass())->element_type();
+  assert(type >= T_BOOLEAN && type <= T_OBJECT, "invalid array element type");
+
+  int length = array->length();
+
+  int type_size;
+  if (type == T_OBJECT) {
+    type_size = sizeof(address);
+  } else {
+    type_size = type2aelembytes(type);
+  }
+
+  size_t length_in_bytes = (size_t)length * type_size;
+
+  // Create a new record if the current record is non-empty and the array can't fit.
+  julong current_record_length = writer->current_record_length();
+  if (current_record_length > 0 &&
+      (current_record_length + header_size + length_in_bytes) > max_juint) {
+    write_current_dump_record_length(writer);
+    write_dump_header(writer);
+
+    // We now have an empty record.
+    current_record_length = 0;
+  }
+
+  // Calculate max bytes we can use.
+  uint max_bytes = max_juint - (header_size + current_record_length);
+
+  // Array too long for the record?
+  // Calculate max length and return it.
+  if (length_in_bytes > max_bytes) {
+    length = max_bytes / type_size;
+    length_in_bytes = (size_t)length * type_size;
+
+    warning("cannot dump array of type %s[] with length %d; truncating to length %d",
+            type2name_tab[type], array->length(), length);
+  }
+  return length;
+}
+
+// creates HPROF_GC_OBJ_ARRAY_DUMP record for the given object array
+void DumperSupport::dump_object_array(DumpWriter* writer, objArrayOop array) {
+  // sizeof(u1) + 2 * sizeof(u4) + sizeof(objectID) + sizeof(classID)
+  short header_size = 1 + 2 * 4 + 2 * sizeof(address);
+
+  int length = calculate_array_max_length(writer, array, header_size);
+
+  writer->write_u1(HPROF_GC_OBJ_ARRAY_DUMP);
+  writer->write_objectID(array);
+  writer->write_u4(STACK_TRACE_ID);
+  writer->write_u4(length);
+
+  // array class ID
+  writer->write_classID(array->klass());
+
+  // [id]* elements
+  for (int index = 0; index < length; index++) {
+    oop o = array->obj_at(index);
+    writer->write_objectID(o);
+  }
+}
+
+#define WRITE_ARRAY(Array, Type, Size, Length) \
+  for (int i = 0; i < Length; i++) { writer->write_##Size((Size)Array->Type##_at(i)); }
+
+// creates HPROF_GC_PRIM_ARRAY_DUMP record for the given type array
+void DumperSupport::dump_prim_array(DumpWriter* writer, typeArrayOop array) {
+  BasicType type = TypeArrayKlass::cast(array->klass())->element_type();
+
+  // 2 * sizeof(u1) + 2 * sizeof(u4) + sizeof(objectID)
+  short header_size = 2 * 1 + 2 * 4 + sizeof(address);
+
+  int length = calculate_array_max_length(writer, array, header_size);
+  int type_size = type2aelembytes(type);
+  u4 length_in_bytes = (u4)length * type_size;
+
+  writer->write_u1(HPROF_GC_PRIM_ARRAY_DUMP);
+  writer->write_objectID(array);
+  writer->write_u4(STACK_TRACE_ID);
+  writer->write_u4(length);
+  writer->write_u1(type2tag(type));
+
+  // nothing to copy
+  if (length == 0) {
+    return;
+  }
+
+  // If the byte ordering is big endian then we can copy most types directly
+
+  switch (type) {
+    case T_INT : {
+      if (Endian::is_Java_byte_ordering_different()) {
+        WRITE_ARRAY(array, int, u4, length);
+      } else {
+        writer->write_raw((void*)(array->int_at_addr(0)), length_in_bytes);
+      }
+      break;
+    }
+    case T_BYTE : {
+      writer->write_raw((void*)(array->byte_at_addr(0)), length_in_bytes);
+      break;
+    }
+    case T_CHAR : {
+      if (Endian::is_Java_byte_ordering_different()) {
+        WRITE_ARRAY(array, char, u2, length);
+      } else {
+        writer->write_raw((void*)(array->char_at_addr(0)), length_in_bytes);
+      }
+      break;
+    }
+    case T_SHORT : {
+      if (Endian::is_Java_byte_ordering_different()) {
+        WRITE_ARRAY(array, short, u2, length);
+      } else {
+        writer->write_raw((void*)(array->short_at_addr(0)), length_in_bytes);
+      }
+      break;
+    }
+    case T_BOOLEAN : {
+      if (Endian::is_Java_byte_ordering_different()) {
+        WRITE_ARRAY(array, bool, u1, length);
+      } else {
+        writer->write_raw((void*)(array->bool_at_addr(0)), length_in_bytes);
+      }
+      break;
+    }
+    case T_LONG : {
+      if (Endian::is_Java_byte_ordering_different()) {
+        WRITE_ARRAY(array, long, u8, length);
+      } else {
+        writer->write_raw((void*)(array->long_at_addr(0)), length_in_bytes);
+      }
+      break;
+    }
+
+    // handle float/doubles in a special value to ensure than NaNs are
+    // written correctly. TO DO: Check if we can avoid this on processors that
+    // use IEEE 754.
+
+    case T_FLOAT : {
+      for (int i = 0; i < length; i++) {
+        dump_float(writer, array->float_at(i));
+      }
+      break;
+    }
+    case T_DOUBLE : {
+      for (int i = 0; i < length; i++) {
+        dump_double(writer, array->double_at(i));
+      }
+      break;
+    }
+    default : ShouldNotReachHere();
+  }
+}
+
+// create a HPROF_FRAME record of the given Method* and bci
+void DumperSupport::dump_stack_frame(DumpWriter* writer,
+                                     int frame_serial_num,
+                                     int class_serial_num,
+                                     Method* m,
+                                     int bci) {
+  int line_number;
+  if (m->is_native()) {
+    line_number = -3;  // native frame
+  } else {
+    line_number = m->line_number_from_bci(bci);
+  }
+
+  write_header(writer, HPROF_FRAME, 4*oopSize + 2*sizeof(u4));
+  writer->write_id(frame_serial_num);               // frame serial number
+  writer->write_symbolID(m->name());                // method's name
+  writer->write_symbolID(m->signature());           // method's signature
+
+  assert(m->method_holder()->is_instance_klass(), "not InstanceKlass");
+  writer->write_symbolID(m->method_holder()->source_file_name());  // source file name
+  writer->write_u4(class_serial_num);               // class serial number
+  writer->write_u4((u4) line_number);               // line number
+}
+
+
+// Support class used to generate HPROF_UTF8 records from the entries in the
+// SymbolTable.
+
+class SymbolTableDumper : public SymbolClosure {
+ private:
+  DumpWriter* _writer;
+  DumpWriter* writer() const                { return _writer; }
+ public:
+  SymbolTableDumper(DumpWriter* writer)     { _writer = writer; }
+  void do_symbol(Symbol** p);
+};
+
+void SymbolTableDumper::do_symbol(Symbol** p) {
+  ResourceMark rm;
+  Symbol* sym = load_symbol(p);
+  int len = sym->utf8_length();
+  if (len > 0) {
+    char* s = sym->as_utf8();
+    DumperSupport::write_header(writer(), HPROF_UTF8, oopSize + len);
+    writer()->write_symbolID(sym);
+    writer()->write_raw(s, len);
+  }
+}
+
+// Support class used to generate HPROF_GC_ROOT_JNI_LOCAL records
+
+class JNILocalsDumper : public OopClosure {
+ private:
+  DumpWriter* _writer;
+  u4 _thread_serial_num;
+  int _frame_num;
+  DumpWriter* writer() const                { return _writer; }
+ public:
+  JNILocalsDumper(DumpWriter* writer, u4 thread_serial_num) {
+    _writer = writer;
+    _thread_serial_num = thread_serial_num;
+    _frame_num = -1;  // default - empty stack
+  }
+  void set_frame_number(int n) { _frame_num = n; }
+  void do_oop(oop* obj_p);
+  void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
+};
+
+
+void JNILocalsDumper::do_oop(oop* obj_p) {
+  // ignore null or deleted handles
+  oop o = *obj_p;
+  if (o != NULL && o != JNIHandles::deleted_handle()) {
+    writer()->write_u1(HPROF_GC_ROOT_JNI_LOCAL);
+    writer()->write_objectID(o);
+    writer()->write_u4(_thread_serial_num);
+    writer()->write_u4((u4)_frame_num);
+  }
+}
+
+
+// Support class used to generate HPROF_GC_ROOT_JNI_GLOBAL records
+
+class JNIGlobalsDumper : public OopClosure {
+ private:
+  DumpWriter* _writer;
+  DumpWriter* writer() const                { return _writer; }
+
+ public:
+  JNIGlobalsDumper(DumpWriter* writer) {
+    _writer = writer;
+  }
+  void do_oop(oop* obj_p);
+  void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
+};
+
+void JNIGlobalsDumper::do_oop(oop* obj_p) {
+  oop o = *obj_p;
+
+  // ignore these
+  if (o == NULL || o == JNIHandles::deleted_handle()) return;
+
+  // we ignore global ref to symbols and other internal objects
+  if (o->is_instance() || o->is_objArray() || o->is_typeArray()) {
+    writer()->write_u1(HPROF_GC_ROOT_JNI_GLOBAL);
+    writer()->write_objectID(o);
+    writer()->write_objectID((oopDesc*)obj_p);      // global ref ID
+  }
+};
+
+
+// Support class used to generate HPROF_GC_ROOT_MONITOR_USED records
+
+class MonitorUsedDumper : public OopClosure {
+ private:
+  DumpWriter* _writer;
+  DumpWriter* writer() const                { return _writer; }
+ public:
+  MonitorUsedDumper(DumpWriter* writer) {
+    _writer = writer;
+  }
+  void do_oop(oop* obj_p) {
+    writer()->write_u1(HPROF_GC_ROOT_MONITOR_USED);
+    writer()->write_objectID(*obj_p);
+  }
+  void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
+};
+
+
+// Support class used to generate HPROF_GC_ROOT_STICKY_CLASS records
+
+class StickyClassDumper : public KlassClosure {
+ private:
+  DumpWriter* _writer;
+  DumpWriter* writer() const                { return _writer; }
+ public:
+  StickyClassDumper(DumpWriter* writer) {
+    _writer = writer;
+  }
+  void do_klass(Klass* k) {
+    if (k->is_instance_klass()) {
+      InstanceKlass* ik = InstanceKlass::cast(k);
+        writer()->write_u1(HPROF_GC_ROOT_STICKY_CLASS);
+        writer()->write_classID(ik);
+      }
+    }
+};
+
+
+class VM_HeapDumper;
+
+// Support class using when iterating over the heap.
+
+class HeapObjectDumper : public ObjectClosure {
+ private:
+  VM_HeapDumper* _dumper;
+  DumpWriter* _writer;
+
+  VM_HeapDumper* dumper()               { return _dumper; }
+  DumpWriter* writer()                  { return _writer; }
+
+  // used to indicate that a record has been writen
+  void mark_end_of_record();
+
+ public:
+  HeapObjectDumper(VM_HeapDumper* dumper, DumpWriter* writer) {
+    _dumper = dumper;
+    _writer = writer;
+  }
+
+  // called for each object in the heap
+  void do_object(oop o);
+};
+
+void HeapObjectDumper::do_object(oop o) {
+  // hide the sentinel for deleted handles
+  if (o == JNIHandles::deleted_handle()) return;
+
+  // skip classes as these emitted as HPROF_GC_CLASS_DUMP records
+  if (o->klass() == SystemDictionary::Class_klass()) {
+    if (!java_lang_Class::is_primitive(o)) {
+      return;
+    }
+  }
+
+  if (o->is_instance()) {
+    // create a HPROF_GC_INSTANCE record for each object
+    DumperSupport::dump_instance(writer(), o);
+    mark_end_of_record();
+  } else if (o->is_objArray()) {
+    // create a HPROF_GC_OBJ_ARRAY_DUMP record for each object array
+    DumperSupport::dump_object_array(writer(), objArrayOop(o));
+    mark_end_of_record();
+  } else if (o->is_typeArray()) {
+    // create a HPROF_GC_PRIM_ARRAY_DUMP record for each type array
+    DumperSupport::dump_prim_array(writer(), typeArrayOop(o));
+    mark_end_of_record();
+  }
+}
+
+// The VM operation that performs the heap dump
+class VM_HeapDumper : public VM_GC_Operation {
+ private:
+  static VM_HeapDumper* _global_dumper;
+  static DumpWriter*    _global_writer;
+  DumpWriter*           _local_writer;
+  JavaThread*           _oome_thread;
+  Method*               _oome_constructor;
+  bool _gc_before_heap_dump;
+  GrowableArray<Klass*>* _klass_map;
+  ThreadStackTrace** _stack_traces;
+  int _num_threads;
+
+  // accessors and setters
+  static VM_HeapDumper* dumper()         {  assert(_global_dumper != NULL, "Error"); return _global_dumper; }
+  static DumpWriter* writer()            {  assert(_global_writer != NULL, "Error"); return _global_writer; }
+  void set_global_dumper() {
+    assert(_global_dumper == NULL, "Error");
+    _global_dumper = this;
+  }
+  void set_global_writer() {
+    assert(_global_writer == NULL, "Error");
+    _global_writer = _local_writer;
+  }
+  void clear_global_dumper() { _global_dumper = NULL; }
+  void clear_global_writer() { _global_writer = NULL; }
+
+  bool skip_operation() const;
+
+  // writes a HPROF_LOAD_CLASS record
+  static void do_load_class(Klass* k);
+
+  // writes a HPROF_GC_CLASS_DUMP record for the given class
+  // (and each array class too)
+  static void do_class_dump(Klass* k);
+
+  // writes a HPROF_GC_CLASS_DUMP records for a given basic type
+  // array (and each multi-dimensional array too)
+  static void do_basic_type_array_class_dump(Klass* k);
+
+  // HPROF_GC_ROOT_THREAD_OBJ records
+  int do_thread(JavaThread* thread, u4 thread_serial_num);
+  void do_threads();
+
+  void add_class_serial_number(Klass* k, int serial_num) {
+    _klass_map->at_put_grow(serial_num, k);
+  }
+
+  // HPROF_TRACE and HPROF_FRAME records
+  void dump_stack_traces();
+
+ public:
+  VM_HeapDumper(DumpWriter* writer, bool gc_before_heap_dump, bool oome) :
+    VM_GC_Operation(0 /* total collections,      dummy, ignored */,
+                    GCCause::_heap_dump /* GC Cause */,
+                    0 /* total full collections, dummy, ignored */,
+                    gc_before_heap_dump) {
+    _local_writer = writer;
+    _gc_before_heap_dump = gc_before_heap_dump;
+    _klass_map = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<Klass*>(INITIAL_CLASS_COUNT, true);
+    _stack_traces = NULL;
+    _num_threads = 0;
+    if (oome) {
+      assert(!Thread::current()->is_VM_thread(), "Dump from OutOfMemoryError cannot be called by the VMThread");
+      // get OutOfMemoryError zero-parameter constructor
+      InstanceKlass* oome_ik = SystemDictionary::OutOfMemoryError_klass();
+      _oome_constructor = oome_ik->find_method(vmSymbols::object_initializer_name(),
+                                                          vmSymbols::void_method_signature());
+      // get thread throwing OOME when generating the heap dump at OOME
+      _oome_thread = JavaThread::current();
+    } else {
+      _oome_thread = NULL;
+      _oome_constructor = NULL;
+    }
+  }
+  ~VM_HeapDumper() {
+    if (_stack_traces != NULL) {
+      for (int i=0; i < _num_threads; i++) {
+        delete _stack_traces[i];
+      }
+      FREE_C_HEAP_ARRAY(ThreadStackTrace*, _stack_traces);
+    }
+    delete _klass_map;
+  }
+
+  VMOp_Type type() const { return VMOp_HeapDumper; }
+  // used to mark sub-record boundary
+  void check_segment_length();
+  void doit();
+};
+
+VM_HeapDumper* VM_HeapDumper::_global_dumper = NULL;
+DumpWriter*    VM_HeapDumper::_global_writer = NULL;
+
+bool VM_HeapDumper::skip_operation() const {
+  return false;
+}
+
+ // writes a HPROF_HEAP_DUMP_SEGMENT record
+void DumperSupport::write_dump_header(DumpWriter* writer) {
+  if (writer->is_open()) {
+    writer->write_u1(HPROF_HEAP_DUMP_SEGMENT);
+    writer->write_u4(0); // current ticks
+
+    // record the starting position for the dump (its length will be fixed up later)
+    writer->set_dump_start(writer->current_offset());
+    writer->write_u4(0);
+  }
+}
+
+// fixes up the length of the current dump record
+void DumperSupport::write_current_dump_record_length(DumpWriter* writer) {
+  if (writer->is_open()) {
+    julong dump_end = writer->bytes_written() + writer->bytes_unwritten();
+    julong dump_len = writer->current_record_length();
+
+    // record length must fit in a u4
+    if (dump_len > max_juint) {
+      warning("record is too large");
+    }
+
+    // seek to the dump start and fix-up the length
+    assert(writer->dump_start() >= 0, "no dump start recorded");
+    writer->seek_to_offset(writer->dump_start());
+    writer->write_u4((u4)dump_len);
+
+    // adjust the total size written to keep the bytes written correct.
+    writer->adjust_bytes_written(-((jlong) sizeof(u4)));
+
+    // seek to dump end so we can continue
+    writer->seek_to_offset(dump_end);
+
+    // no current dump record
+    writer->set_dump_start((jlong)-1);
+  }
+}
+
+// used on a sub-record boundary to check if we need to start a
+// new segment.
+void VM_HeapDumper::check_segment_length() {
+  if (writer()->is_open()) {
+    julong dump_len = writer()->current_record_length();
+
+    if (dump_len > 2UL*G) {
+      DumperSupport::write_current_dump_record_length(writer());
+      DumperSupport::write_dump_header(writer());
+    }
+  }
+}
+
+// fixes up the current dump record and writes HPROF_HEAP_DUMP_END record
+void DumperSupport::end_of_dump(DumpWriter* writer) {
+  if (writer->is_open()) {
+    write_current_dump_record_length(writer);
+
+    writer->write_u1(HPROF_HEAP_DUMP_END);
+    writer->write_u4(0);
+    writer->write_u4(0);
+  }
+}
+
+// marks sub-record boundary
+void HeapObjectDumper::mark_end_of_record() {
+  dumper()->check_segment_length();
+}
+
+// writes a HPROF_LOAD_CLASS record for the class (and each of its
+// array classes)
+void VM_HeapDumper::do_load_class(Klass* k) {
+  static u4 class_serial_num = 0;
+
+  // len of HPROF_LOAD_CLASS record
+  u4 remaining = 2*oopSize + 2*sizeof(u4);
+
+  // write a HPROF_LOAD_CLASS for the class and each array class
+  do {
+    DumperSupport::write_header(writer(), HPROF_LOAD_CLASS, remaining);
+
+    // class serial number is just a number
+    writer()->write_u4(++class_serial_num);
+
+    // class ID
+    Klass* klass = k;
+    writer()->write_classID(klass);
+
+    // add the Klass* and class serial number pair
+    dumper()->add_class_serial_number(klass, class_serial_num);
+
+    writer()->write_u4(STACK_TRACE_ID);
+
+    // class name ID
+    Symbol* name = klass->name();
+    writer()->write_symbolID(name);
+
+    // write a LOAD_CLASS record for the array type (if it exists)
+    k = klass->array_klass_or_null();
+  } while (k != NULL);
+}
+
+// writes a HPROF_GC_CLASS_DUMP record for the given class
+void VM_HeapDumper::do_class_dump(Klass* k) {
+  if (k->is_instance_klass()) {
+    DumperSupport::dump_class_and_array_classes(writer(), k);
+  }
+}
+
+// writes a HPROF_GC_CLASS_DUMP records for a given basic type
+// array (and each multi-dimensional array too)
+void VM_HeapDumper::do_basic_type_array_class_dump(Klass* k) {
+  DumperSupport::dump_basic_type_array_class(writer(), k);
+}
+
+// Walk the stack of the given thread.
+// Dumps a HPROF_GC_ROOT_JAVA_FRAME record for each local
+// Dumps a HPROF_GC_ROOT_JNI_LOCAL record for each JNI local
+//
+// It returns the number of Java frames in this thread stack
+int VM_HeapDumper::do_thread(JavaThread* java_thread, u4 thread_serial_num) {
+  JNILocalsDumper blk(writer(), thread_serial_num);
+
+  oop threadObj = java_thread->threadObj();
+  assert(threadObj != NULL, "sanity check");
+
+  int stack_depth = 0;
+  if (java_thread->has_last_Java_frame()) {
+
+    // vframes are resource allocated
+    Thread* current_thread = Thread::current();
+    ResourceMark rm(current_thread);
+    HandleMark hm(current_thread);
+
+    RegisterMap reg_map(java_thread);
+    frame f = java_thread->last_frame();
+    vframe* vf = vframe::new_vframe(&f, &reg_map, java_thread);
+    frame* last_entry_frame = NULL;
+    int extra_frames = 0;
+
+    if (java_thread == _oome_thread && _oome_constructor != NULL) {
+      extra_frames++;
+    }
+    while (vf != NULL) {
+      blk.set_frame_number(stack_depth);
+      if (vf->is_java_frame()) {
+
+        // java frame (interpreted, compiled, ...)
+        javaVFrame *jvf = javaVFrame::cast(vf);
+        if (!(jvf->method()->is_native())) {
+          StackValueCollection* locals = jvf->locals();
+          for (int slot=0; slot<locals->size(); slot++) {
+            if (locals->at(slot)->type() == T_OBJECT) {
+              oop o = locals->obj_at(slot)();
+
+              if (o != NULL) {
+                writer()->write_u1(HPROF_GC_ROOT_JAVA_FRAME);
+                writer()->write_objectID(o);
+                writer()->write_u4(thread_serial_num);
+                writer()->write_u4((u4) (stack_depth + extra_frames));
+              }
+            }
+          }
+          StackValueCollection *exprs = jvf->expressions();
+          for(int index = 0; index < exprs->size(); index++) {
+            if (exprs->at(index)->type() == T_OBJECT) {
+               oop o = exprs->obj_at(index)();
+               if (o != NULL) {
+                 writer()->write_u1(HPROF_GC_ROOT_JAVA_FRAME);
+                 writer()->write_objectID(o);
+                 writer()->write_u4(thread_serial_num);
+                 writer()->write_u4((u4) (stack_depth + extra_frames));
+               }
+             }
+          }
+        } else {
+          // native frame
+          if (stack_depth == 0) {
+            // JNI locals for the top frame.
+            java_thread->active_handles()->oops_do(&blk);
+          } else {
+            if (last_entry_frame != NULL) {
+              // JNI locals for the entry frame
+              assert(last_entry_frame->is_entry_frame(), "checking");
+              last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(&blk);
+            }
+          }
+        }
+        // increment only for Java frames
+        stack_depth++;
+        last_entry_frame = NULL;
+
+      } else {
+        // externalVFrame - if it's an entry frame then report any JNI locals
+        // as roots when we find the corresponding native javaVFrame
+        frame* fr = vf->frame_pointer();
+        assert(fr != NULL, "sanity check");
+        if (fr->is_entry_frame()) {
+          last_entry_frame = fr;
+        }
+      }
+      vf = vf->sender();
+    }
+  } else {
+    // no last java frame but there may be JNI locals
+    java_thread->active_handles()->oops_do(&blk);
+  }
+  return stack_depth;
+}
+
+
+// write a HPROF_GC_ROOT_THREAD_OBJ record for each java thread. Then walk
+// the stack so that locals and JNI locals are dumped.
+void VM_HeapDumper::do_threads() {
+  for (int i=0; i < _num_threads; i++) {
+    JavaThread* thread = _stack_traces[i]->thread();
+    oop threadObj = thread->threadObj();
+    u4 thread_serial_num = i+1;
+    u4 stack_serial_num = thread_serial_num + STACK_TRACE_ID;
+    writer()->write_u1(HPROF_GC_ROOT_THREAD_OBJ);
+    writer()->write_objectID(threadObj);
+    writer()->write_u4(thread_serial_num);  // thread number
+    writer()->write_u4(stack_serial_num);   // stack trace serial number
+    int num_frames = do_thread(thread, thread_serial_num);
+    assert(num_frames == _stack_traces[i]->get_stack_depth(),
+           "total number of Java frames not matched");
+  }
+}
+
+
+// The VM operation that dumps the heap. The dump consists of the following
+// records:
+//
+//  HPROF_HEADER
+//  [HPROF_UTF8]*
+//  [HPROF_LOAD_CLASS]*
+//  [[HPROF_FRAME]*|HPROF_TRACE]*
+//  [HPROF_GC_CLASS_DUMP]*
+//  [HPROF_HEAP_DUMP_SEGMENT]*
+//  HPROF_HEAP_DUMP_END
+//
+// The HPROF_TRACE records represent the stack traces where the heap dump
+// is generated and a "dummy trace" record which does not include
+// any frames. The dummy trace record is used to be referenced as the
+// unknown object alloc site.
+//
+// Each HPROF_HEAP_DUMP_SEGMENT record has a length followed by sub-records.
+// To allow the heap dump be generated in a single pass we remember the position
+// of the dump length and fix it up after all sub-records have been written.
+// To generate the sub-records we iterate over the heap, writing
+// HPROF_GC_INSTANCE_DUMP, HPROF_GC_OBJ_ARRAY_DUMP, and HPROF_GC_PRIM_ARRAY_DUMP
+// records as we go. Once that is done we write records for some of the GC
+// roots.
+
+void VM_HeapDumper::doit() {
+
+  HandleMark hm;
+  CollectedHeap* ch = Universe::heap();
+
+  ch->ensure_parsability(false); // must happen, even if collection does
+                                 // not happen (e.g. due to GCLocker)
+
+  if (_gc_before_heap_dump) {
+    if (GCLocker::is_active()) {
+      warning("GC locker is held; pre-heapdump GC was skipped");
+    } else {
+      ch->collect_as_vm_thread(GCCause::_heap_dump);
+    }
+  }
+
+  // At this point we should be the only dumper active, so
+  // the following should be safe.
+  set_global_dumper();
+  set_global_writer();
+
+  // Write the file header - we always use 1.0.2
+  size_t used = ch->used();
+  const char* header = "JAVA PROFILE 1.0.2";
+
+  // header is few bytes long - no chance to overflow int
+  writer()->write_raw((void*)header, (int)strlen(header));
+  writer()->write_u1(0); // terminator
+  writer()->write_u4(oopSize);
+  writer()->write_u8(os::javaTimeMillis());
+
+  // HPROF_UTF8 records
+  SymbolTableDumper sym_dumper(writer());
+  SymbolTable::symbols_do(&sym_dumper);
+
+  // write HPROF_LOAD_CLASS records
+  ClassLoaderDataGraph::classes_do(&do_load_class);
+  Universe::basic_type_classes_do(&do_load_class);
+
+  // write HPROF_FRAME and HPROF_TRACE records
+  // this must be called after _klass_map is built when iterating the classes above.
+  dump_stack_traces();
+
+  // write HPROF_HEAP_DUMP_SEGMENT
+  DumperSupport::write_dump_header(writer());
+
+  // Writes HPROF_GC_CLASS_DUMP records
+  ClassLoaderDataGraph::classes_do(&do_class_dump);
+  Universe::basic_type_classes_do(&do_basic_type_array_class_dump);
+  check_segment_length();
+
+  // writes HPROF_GC_INSTANCE_DUMP records.
+  // After each sub-record is written check_segment_length will be invoked
+  // to check if the current segment exceeds a threshold. If so, a new
+  // segment is started.
+  // The HPROF_GC_CLASS_DUMP and HPROF_GC_INSTANCE_DUMP are the vast bulk
+  // of the heap dump.
+  HeapObjectDumper obj_dumper(this, writer());
+  Universe::heap()->safe_object_iterate(&obj_dumper);
+
+  // HPROF_GC_ROOT_THREAD_OBJ + frames + jni locals
+  do_threads();
+  check_segment_length();
+
+  // HPROF_GC_ROOT_MONITOR_USED
+  MonitorUsedDumper mon_dumper(writer());
+  ObjectSynchronizer::oops_do(&mon_dumper);
+  check_segment_length();
+
+  // HPROF_GC_ROOT_JNI_GLOBAL
+  JNIGlobalsDumper jni_dumper(writer());
+  JNIHandles::oops_do(&jni_dumper);
+  check_segment_length();
+
+  // HPROF_GC_ROOT_STICKY_CLASS
+  // These should be classes in the NULL class loader data, and not all classes
+  // if !ClassUnloading
+  StickyClassDumper class_dumper(writer());
+  ClassLoaderData::the_null_class_loader_data()->classes_do(&class_dumper);
+
+  // fixes up the length of the dump record and writes the HPROF_HEAP_DUMP_END record.
+  DumperSupport::end_of_dump(writer());
+
+  // Now we clear the global variables, so that a future dumper might run.
+  clear_global_dumper();
+  clear_global_writer();
+}
+
+void VM_HeapDumper::dump_stack_traces() {
+  // write a HPROF_TRACE record without any frames to be referenced as object alloc sites
+  DumperSupport::write_header(writer(), HPROF_TRACE, 3*sizeof(u4));
+  writer()->write_u4((u4) STACK_TRACE_ID);
+  writer()->write_u4(0);                    // thread number
+  writer()->write_u4(0);                    // frame count
+
+  _stack_traces = NEW_C_HEAP_ARRAY(ThreadStackTrace*, Threads::number_of_threads(), mtInternal);
+  int frame_serial_num = 0;
+  for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
+    oop threadObj = thread->threadObj();
+    if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
+      // dump thread stack trace
+      ThreadStackTrace* stack_trace = new ThreadStackTrace(thread, false);
+      stack_trace->dump_stack_at_safepoint(-1);
+      _stack_traces[_num_threads++] = stack_trace;
+
+      // write HPROF_FRAME records for this thread's stack trace
+      int depth = stack_trace->get_stack_depth();
+      int thread_frame_start = frame_serial_num;
+      int extra_frames = 0;
+      // write fake frame that makes it look like the thread, which caused OOME,
+      // is in the OutOfMemoryError zero-parameter constructor
+      if (thread == _oome_thread && _oome_constructor != NULL) {
+        int oome_serial_num = _klass_map->find(_oome_constructor->method_holder());
+        // the class serial number starts from 1
+        assert(oome_serial_num > 0, "OutOfMemoryError class not found");
+        DumperSupport::dump_stack_frame(writer(), ++frame_serial_num, oome_serial_num,
+                                        _oome_constructor, 0);
+        extra_frames++;
+      }
+      for (int j=0; j < depth; j++) {
+        StackFrameInfo* frame = stack_trace->stack_frame_at(j);
+        Method* m = frame->method();
+        int class_serial_num = _klass_map->find(m->method_holder());
+        // the class serial number starts from 1
+        assert(class_serial_num > 0, "class not found");
+        DumperSupport::dump_stack_frame(writer(), ++frame_serial_num, class_serial_num, m, frame->bci());
+      }
+      depth += extra_frames;
+
+      // write HPROF_TRACE record for one thread
+      DumperSupport::write_header(writer(), HPROF_TRACE, 3*sizeof(u4) + depth*oopSize);
+      int stack_serial_num = _num_threads + STACK_TRACE_ID;
+      writer()->write_u4(stack_serial_num);      // stack trace serial number
+      writer()->write_u4((u4) _num_threads);     // thread serial number
+      writer()->write_u4(depth);                 // frame count
+      for (int j=1; j <= depth; j++) {
+        writer()->write_id(thread_frame_start + j);
+      }
+    }
+  }
+}
+
+// dump the heap to given path.
+int HeapDumper::dump(const char* path) {
+  assert(path != NULL && strlen(path) > 0, "path missing");
+
+  // print message in interactive case
+  if (print_to_tty()) {
+    tty->print_cr("Dumping heap to %s ...", path);
+    timer()->start();
+  }
+
+  // create the dump writer. If the file can be opened then bail
+  DumpWriter writer(path);
+  if (!writer.is_open()) {
+    set_error(writer.error());
+    if (print_to_tty()) {
+      tty->print_cr("Unable to create %s: %s", path,
+        (error() != NULL) ? error() : "reason unknown");
+    }
+    return -1;
+  }
+
+  // generate the dump
+  VM_HeapDumper dumper(&writer, _gc_before_heap_dump, _oome);
+  if (Thread::current()->is_VM_thread()) {
+    assert(SafepointSynchronize::is_at_safepoint(), "Expected to be called at a safepoint");
+    dumper.doit();
+  } else {
+    VMThread::execute(&dumper);
+  }
+
+  // close dump file and record any error that the writer may have encountered
+  writer.close();
+  set_error(writer.error());
+
+  // print message in interactive case
+  if (print_to_tty()) {
+    timer()->stop();
+    if (error() == NULL) {
+      tty->print_cr("Heap dump file created [" JULONG_FORMAT " bytes in %3.3f secs]",
+                    writer.bytes_written(), timer()->seconds());
+    } else {
+      tty->print_cr("Dump file is incomplete: %s", writer.error());
+    }
+  }
+
+  return (writer.error() == NULL) ? 0 : -1;
+}
+
+// stop timer (if still active), and free any error string we might be holding
+HeapDumper::~HeapDumper() {
+  if (timer()->is_active()) {
+    timer()->stop();
+  }
+  set_error(NULL);
+}
+
+
+// returns the error string (resource allocated), or NULL
+char* HeapDumper::error_as_C_string() const {
+  if (error() != NULL) {
+    char* str = NEW_RESOURCE_ARRAY(char, strlen(error())+1);
+    strcpy(str, error());
+    return str;
+  } else {
+    return NULL;
+  }
+}
+
+// set the error string
+void HeapDumper::set_error(char* error) {
+  if (_error != NULL) {
+    os::free(_error);
+  }
+  if (error == NULL) {
+    _error = NULL;
+  } else {
+    _error = os::strdup(error);
+    assert(_error != NULL, "allocation failure");
+  }
+}
+
+// Called by out-of-memory error reporting by a single Java thread
+// outside of a JVM safepoint
+void HeapDumper::dump_heap_from_oome() {
+  HeapDumper::dump_heap(true);
+}
+
+// Called by error reporting by a single Java thread outside of a JVM safepoint,
+// or by heap dumping by the VM thread during a (GC) safepoint. Thus, these various
+// callers are strictly serialized and guaranteed not to interfere below. For more
+// general use, however, this method will need modification to prevent
+// inteference when updating the static variables base_path and dump_file_seq below.
+void HeapDumper::dump_heap() {
+  HeapDumper::dump_heap(false);
+}
+
+void HeapDumper::dump_heap(bool oome) {
+  static char base_path[JVM_MAXPATHLEN] = {'\0'};
+  static uint dump_file_seq = 0;
+  char* my_path;
+  const int max_digit_chars = 20;
+
+  const char* dump_file_name = "java_pid";
+  const char* dump_file_ext  = ".hprof";
+
+  // The dump file defaults to java_pid<pid>.hprof in the current working
+  // directory. HeapDumpPath=<file> can be used to specify an alternative
+  // dump file name or a directory where dump file is created.
+  if (dump_file_seq == 0) { // first time in, we initialize base_path
+    // Calculate potentially longest base path and check if we have enough
+    // allocated statically.
+    const size_t total_length =
+                      (HeapDumpPath == NULL ? 0 : strlen(HeapDumpPath)) +
+                      strlen(os::file_separator()) + max_digit_chars +
+                      strlen(dump_file_name) + strlen(dump_file_ext) + 1;
+    if (total_length > sizeof(base_path)) {
+      warning("Cannot create heap dump file.  HeapDumpPath is too long.");
+      return;
+    }
+
+    bool use_default_filename = true;
+    if (HeapDumpPath == NULL || HeapDumpPath[0] == '\0') {
+      // HeapDumpPath=<file> not specified
+    } else {
+      strcpy(base_path, HeapDumpPath);
+      // check if the path is a directory (must exist)
+      DIR* dir = os::opendir(base_path);
+      if (dir == NULL) {
+        use_default_filename = false;
+      } else {
+        // HeapDumpPath specified a directory. We append a file separator
+        // (if needed).
+        os::closedir(dir);
+        size_t fs_len = strlen(os::file_separator());
+        if (strlen(base_path) >= fs_len) {
+          char* end = base_path;
+          end += (strlen(base_path) - fs_len);
+          if (strcmp(end, os::file_separator()) != 0) {
+            strcat(base_path, os::file_separator());
+          }
+        }
+      }
+    }
+    // If HeapDumpPath wasn't a file name then we append the default name
+    if (use_default_filename) {
+      const size_t dlen = strlen(base_path);  // if heap dump dir specified
+      jio_snprintf(&base_path[dlen], sizeof(base_path)-dlen, "%s%d%s",
+                   dump_file_name, os::current_process_id(), dump_file_ext);
+    }
+    const size_t len = strlen(base_path) + 1;
+    my_path = (char*)os::malloc(len, mtInternal);
+    if (my_path == NULL) {
+      warning("Cannot create heap dump file.  Out of system memory.");
+      return;
+    }
+    strncpy(my_path, base_path, len);
+  } else {
+    // Append a sequence number id for dumps following the first
+    const size_t len = strlen(base_path) + max_digit_chars + 2; // for '.' and \0
+    my_path = (char*)os::malloc(len, mtInternal);
+    if (my_path == NULL) {
+      warning("Cannot create heap dump file.  Out of system memory.");
+      return;
+    }
+    jio_snprintf(my_path, len, "%s.%d", base_path, dump_file_seq);
+  }
+  dump_file_seq++;   // increment seq number for next time we dump
+
+  HeapDumper dumper(false /* no GC before heap dump */,
+                    true  /* send to tty */,
+                    oome  /* pass along out-of-memory-error flag */);
+  dumper.dump(my_path);
+  os::free(my_path);
+}