--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/runtime/thread.hpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,1757 @@
+/*
+ * Copyright 1997-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+class ThreadSafepointState;
+class ThreadProfiler;
+
+class JvmtiThreadState;
+class JvmtiGetLoadedClassesClosure;
+class ThreadStatistics;
+class ConcurrentLocksDump;
+class ParkEvent ;
+
+class ciEnv;
+class CompileThread;
+class CompileLog;
+class CompileTask;
+class CompileQueue;
+class CompilerCounters;
+class vframeArray;
+
+class DeoptResourceMark;
+class jvmtiDeferredLocalVariableSet;
+
+class GCTaskQueue;
+class ThreadClosure;
+class IdealGraphPrinter;
+
+// Class hierarchy
+// - Thread
+//   - VMThread
+//   - JavaThread
+//   - WatcherThread
+
+class Thread: public ThreadShadow {
+  friend class VMStructs;
+ private:
+  // Exception handling
+  // (Note: _pending_exception and friends are in ThreadShadow)
+  //oop       _pending_exception;                // pending exception for current thread
+  // const char* _exception_file;                   // file information for exception (debugging only)
+  // int         _exception_line;                   // line information for exception (debugging only)
+
+  // Support for forcing alignment of thread objects for biased locking
+  void*       _real_malloc_address;
+ public:
+  void* operator new(size_t size);
+  void  operator delete(void* p);
+ private:
+
+  // ***************************************************************
+  // Suspend and resume support
+  // ***************************************************************
+  //
+  // VM suspend/resume no longer exists - it was once used for various
+  // things including safepoints but was deprecated and finally removed
+  // in Java 7. Because VM suspension was considered "internal" Java-level
+  // suspension was considered "external", and this legacy naming scheme
+  // remains.
+  //
+  // External suspend/resume requests come from JVM_SuspendThread,
+  // JVM_ResumeThread, JVMTI SuspendThread, and finally JVMTI
+  // ResumeThread. External
+  // suspend requests cause _external_suspend to be set and external
+  // resume requests cause _external_suspend to be cleared.
+  // External suspend requests do not nest on top of other external
+  // suspend requests. The higher level APIs reject suspend requests
+  // for already suspended threads.
+  //
+  // The external_suspend
+  // flag is checked by has_special_runtime_exit_condition() and java thread
+  // will self-suspend when handle_special_runtime_exit_condition() is
+  // called. Most uses of the _thread_blocked state in JavaThreads are
+  // considered the same as being externally suspended; if the blocking
+  // condition lifts, the JavaThread will self-suspend. Other places
+  // where VM checks for external_suspend include:
+  //   + mutex granting (do not enter monitors when thread is suspended)
+  //   + state transitions from _thread_in_native
+  //
+  // In general, java_suspend() does not wait for an external suspend
+  // request to complete. When it returns, the only guarantee is that
+  // the _external_suspend field is true.
+  //
+  // wait_for_ext_suspend_completion() is used to wait for an external
+  // suspend request to complete. External suspend requests are usually
+  // followed by some other interface call that requires the thread to
+  // be quiescent, e.g., GetCallTrace(). By moving the "wait time" into
+  // the interface that requires quiescence, we give the JavaThread a
+  // chance to self-suspend before we need it to be quiescent. This
+  // improves overall suspend/query performance.
+  //
+  // _suspend_flags controls the behavior of java_ suspend/resume.
+  // It must be set under the protection of SR_lock. Read from the flag is
+  // OK without SR_lock as long as the value is only used as a hint.
+  // (e.g., check _external_suspend first without lock and then recheck
+  // inside SR_lock and finish the suspension)
+  //
+  // _suspend_flags is also overloaded for other "special conditions" so
+  // that a single check indicates whether any special action is needed
+  // eg. for async exceptions.
+  // -------------------------------------------------------------------
+  // Notes:
+  // 1. The suspend/resume logic no longer uses ThreadState in OSThread
+  // but we still update its value to keep other part of the system (mainly
+  // JVMTI) happy. ThreadState is legacy code (see notes in
+  // osThread.hpp).
+  //
+  // 2. It would be more natural if set_external_suspend() is private and
+  // part of java_suspend(), but that probably would affect the suspend/query
+  // performance. Need more investigation on this.
+  //
+
+  // suspend/resume lock: used for self-suspend
+  Monitor*    _SR_lock;
+
+ protected:
+  enum SuspendFlags {
+    // NOTE: avoid using the sign-bit as cc generates different test code
+    //       when the sign-bit is used, and sometimes incorrectly - see CR 6398077
+
+    _external_suspend       = 0x20000000U, // thread is asked to self suspend
+    _ext_suspended          = 0x40000000U, // thread has self-suspended
+    _deopt_suspend          = 0x10000000U, // thread needs to self suspend for deopt
+
+    _has_async_exception    = 0x00000001U  // there is a pending async exception
+  };
+
+  // various suspension related flags - atomically updated
+  // overloaded for async exception checking in check_special_condition_for_native_trans.
+  volatile uint32_t _suspend_flags;
+
+ private:
+  int _num_nested_signal;
+
+ public:
+  void enter_signal_handler() { _num_nested_signal++; }
+  void leave_signal_handler() { _num_nested_signal--; }
+  bool is_inside_signal_handler() const  { return _num_nested_signal > 0; }
+
+ private:
+  // Debug tracing
+  static void trace(const char* msg, const Thread* const thread) PRODUCT_RETURN;
+
+  // Active_handles points to a block of handles
+  JNIHandleBlock* _active_handles;
+
+  // One-element thread local free list
+  JNIHandleBlock* _free_handle_block;
+
+  // Point to the last handle mark
+  HandleMark* _last_handle_mark;
+
+  // The parity of the last strong_roots iteration in which this thread was
+  // claimed as a task.
+  jint _oops_do_parity;
+
+  public:
+   void set_last_handle_mark(HandleMark* mark)   { _last_handle_mark = mark; }
+    HandleMark* last_handle_mark() const          { return _last_handle_mark; }
+  private:
+
+  // debug support for checking if code does allow safepoints or not
+  // GC points in the VM can happen because of allocation, invoking a VM operation, or blocking on
+  // mutex, or blocking on an object synchronizer (Java locking).
+  // If !allow_safepoint(), then an assertion failure will happen in any of the above cases
+  // If !allow_allocation(), then an assertion failure will happen during allocation
+  // (Hence, !allow_safepoint() => !allow_allocation()).
+  //
+  // The two classes No_Safepoint_Verifier and No_Allocation_Verifier are used to set these counters.
+  //
+  NOT_PRODUCT(int _allow_safepoint_count;)       // If 0, thread allow a safepoint to happen
+  debug_only (int _allow_allocation_count;)      // If 0, the thread is allowed to allocate oops.
+
+  // Record when GC is locked out via the GC_locker mechanism
+  CHECK_UNHANDLED_OOPS_ONLY(int _gc_locked_out_count;)
+
+  friend class No_Alloc_Verifier;
+  friend class No_Safepoint_Verifier;
+  friend class Pause_No_Safepoint_Verifier;
+  friend class ThreadLocalStorage;
+  friend class GC_locker;
+
+  // In order for all threads to be able to use fast locking, we need to know the highest stack
+  // address of where a lock is on the stack (stacks normally grow towards lower addresses). This
+  // variable is initially set to NULL, indicating no locks are used by the thread. During the thread's
+  // execution, it will be set whenever locking can happen, i.e., when we call out to Java code or use
+  // an ObjectLocker. The value is never decreased, hence, it will over the lifetime of a thread
+  // approximate the real stackbase.
+  address _highest_lock;                         // Highest stack address where a JavaLock exist
+
+  ThreadLocalAllocBuffer _tlab;                  // Thread-local eden
+
+  int   _vm_operation_started_count;             // VM_Operation support
+  int   _vm_operation_completed_count;           // VM_Operation support
+
+  ObjectMonitor* _current_pending_monitor;       // ObjectMonitor this thread
+                                                 // is waiting to lock
+  bool _current_pending_monitor_is_from_java;    // locking is from Java code
+
+  // ObjectMonitor on which this thread called Object.wait()
+  ObjectMonitor* _current_waiting_monitor;
+
+  // Private thread-local objectmonitor list - a simple cache organized as a SLL.
+ public:
+  ObjectMonitor * omFreeList ;
+  int omFreeCount ;                             // length of omFreeList
+  int omFreeProvision ;                         // reload chunk size
+
+ public:
+  enum {
+    is_definitely_current_thread = true
+  };
+
+  // Constructor
+  Thread();
+  virtual ~Thread();
+
+  // initializtion
+  void initialize_thread_local_storage();
+
+  // thread entry point
+  virtual void run();
+
+  // Testers
+  virtual bool is_VM_thread()       const            { return false; }
+  virtual bool is_Java_thread()     const            { return false; }
+  // Remove this ifdef when C1 is ported to the compiler interface.
+  virtual bool is_Compiler_thread() const            { return false; }
+  virtual bool is_hidden_from_external_view() const  { return false; }
+  virtual bool is_jvmti_agent_thread() const         { return false; }
+  // True iff the thread can perform GC operations at a safepoint.
+  // Generally will be true only of VM thread and parallel GC WorkGang
+  // threads.
+  virtual bool is_GC_task_thread() const             { return false; }
+  virtual bool is_Watcher_thread() const             { return false; }
+  virtual bool is_ConcurrentGC_thread() const        { return false; }
+
+  virtual char* name() const { return (char*)"Unknown thread"; }
+
+  // Returns the current thread
+  static inline Thread* current();
+
+  // Common thread operations
+  static void set_priority(Thread* thread, ThreadPriority priority);
+  static ThreadPriority get_priority(const Thread* const thread);
+  static void start(Thread* thread);
+  static void interrupt(Thread* thr);
+  static bool is_interrupted(Thread* thr, bool clear_interrupted);
+
+  Monitor* SR_lock() const                       { return _SR_lock; }
+
+  bool has_async_exception() const { return (_suspend_flags & _has_async_exception) != 0; }
+
+  void set_suspend_flag(SuspendFlags f) {
+    assert(sizeof(jint) == sizeof(_suspend_flags), "size mismatch");
+    uint32_t flags;
+    do {
+      flags = _suspend_flags;
+    }
+    while (Atomic::cmpxchg((jint)(flags | f),
+                           (volatile jint*)&_suspend_flags,
+                           (jint)flags) != (jint)flags);
+  }
+  void clear_suspend_flag(SuspendFlags f) {
+    assert(sizeof(jint) == sizeof(_suspend_flags), "size mismatch");
+    uint32_t flags;
+    do {
+      flags = _suspend_flags;
+    }
+    while (Atomic::cmpxchg((jint)(flags & ~f),
+                           (volatile jint*)&_suspend_flags,
+                           (jint)flags) != (jint)flags);
+  }
+
+  void set_has_async_exception() {
+    set_suspend_flag(_has_async_exception);
+  }
+  void clear_has_async_exception() {
+    clear_suspend_flag(_has_async_exception);
+  }
+
+  // Support for Unhandled Oop detection
+#ifdef CHECK_UNHANDLED_OOPS
+ private:
+  UnhandledOops *_unhandled_oops;
+ public:
+  UnhandledOops* unhandled_oops()               { return _unhandled_oops; }
+  // Mark oop safe for gc.  It may be stack allocated but won't move.
+  void allow_unhandled_oop(oop *op)              {
+    if (CheckUnhandledOops) unhandled_oops()->allow_unhandled_oop(op);
+  }
+  // Clear oops at safepoint so crashes point to unhandled oop violator
+  void clear_unhandled_oops()                   {
+    if (CheckUnhandledOops) unhandled_oops()->clear_unhandled_oops();
+  }
+  bool is_gc_locked_out() { return _gc_locked_out_count > 0; }
+#endif // CHECK_UNHANDLED_OOPS
+
+ public:
+  // Installs a pending exception to be inserted later
+  static void send_async_exception(oop thread_oop, oop java_throwable);
+
+  // Resource area
+  ResourceArea* resource_area() const            { return _resource_area; }
+  void set_resource_area(ResourceArea* area)     { _resource_area = area; }
+
+  OSThread* osthread() const                     { return _osthread;   }
+  void set_osthread(OSThread* thread)            { _osthread = thread; }
+
+  // JNI handle support
+  JNIHandleBlock* active_handles() const         { return _active_handles; }
+  void set_active_handles(JNIHandleBlock* block) { _active_handles = block; }
+  JNIHandleBlock* free_handle_block() const      { return _free_handle_block; }
+  void set_free_handle_block(JNIHandleBlock* block) { _free_handle_block = block; }
+
+  // Internal handle support
+  HandleArea* handle_area() const                { return _handle_area; }
+  void set_handle_area(HandleArea* area)         { _handle_area = area; }
+
+  // Thread-Local Allocation Buffer (TLAB) support
+  ThreadLocalAllocBuffer& tlab()                 { return _tlab; }
+  void initialize_tlab() {
+    if (UseTLAB) {
+      tlab().initialize();
+    }
+  }
+
+  // VM operation support
+  int vm_operation_ticket()                      { return ++_vm_operation_started_count; }
+  int vm_operation_completed_count()             { return _vm_operation_completed_count; }
+  void increment_vm_operation_completed_count()  { _vm_operation_completed_count++; }
+
+  // For tracking the heavyweight monitor the thread is pending on.
+  ObjectMonitor* current_pending_monitor() {
+    return _current_pending_monitor;
+  }
+  void set_current_pending_monitor(ObjectMonitor* monitor) {
+    _current_pending_monitor = monitor;
+  }
+  void set_current_pending_monitor_is_from_java(bool from_java) {
+    _current_pending_monitor_is_from_java = from_java;
+  }
+  bool current_pending_monitor_is_from_java() {
+    return _current_pending_monitor_is_from_java;
+  }
+
+  // For tracking the ObjectMonitor on which this thread called Object.wait()
+  ObjectMonitor* current_waiting_monitor() {
+    return _current_waiting_monitor;
+  }
+  void set_current_waiting_monitor(ObjectMonitor* monitor) {
+    _current_waiting_monitor = monitor;
+  }
+
+  // GC support
+  // Apply "f->do_oop" to all root oops in "this".
+  void oops_do(OopClosure* f);
+
+  // Handles the parallel case for the method below.
+private:
+  bool claim_oops_do_par_case(int collection_parity);
+public:
+  // Requires that "collection_parity" is that of the current strong roots
+  // iteration.  If "is_par" is false, sets the parity of "this" to
+  // "collection_parity", and returns "true".  If "is_par" is true,
+  // uses an atomic instruction to set the current threads parity to
+  // "collection_parity", if it is not already.  Returns "true" iff the
+  // calling thread does the update, this indicates that the calling thread
+  // has claimed the thread's stack as a root groop in the current
+  // collection.
+  bool claim_oops_do(bool is_par, int collection_parity) {
+    if (!is_par) {
+      _oops_do_parity = collection_parity;
+      return true;
+    } else {
+      return claim_oops_do_par_case(collection_parity);
+    }
+  }
+
+  // Sweeper support
+  void nmethods_do();
+
+  // Fast-locking support
+  address highest_lock() const                   { return _highest_lock; }
+  void update_highest_lock(address base)         { if (base > _highest_lock) _highest_lock = base; }
+
+  // Tells if adr belong to this thread. This is used
+  // for checking if a lock is owned by the running thread.
+  // Warning: the method can only be used on the running thread
+  // Fast lock support uses these methods
+  virtual bool lock_is_in_stack(address adr) const;
+  virtual bool is_lock_owned(address adr) const;
+
+  // Check if address is in the stack of the thread (not just for locks).
+  bool is_in_stack(address adr) const;
+
+  // Sets this thread as starting thread. Returns failure if thread
+  // creation fails due to lack of memory, too many threads etc.
+  bool set_as_starting_thread();
+
+ protected:
+  // OS data associated with the thread
+  OSThread* _osthread;  // Platform-specific thread information
+
+  // Thread local resource area for temporary allocation within the VM
+  ResourceArea* _resource_area;
+
+  // Thread local handle area for allocation of handles within the VM
+  HandleArea* _handle_area;
+
+  // Support for stack overflow handling, get_thread, etc.
+  address          _stack_base;
+  size_t           _stack_size;
+  uintptr_t        _self_raw_id;      // used by get_thread (mutable)
+  int              _lgrp_id;
+
+ public:
+  // Stack overflow support
+  address stack_base() const           { assert(_stack_base != NULL,"Sanity check"); return _stack_base; }
+
+  void    set_stack_base(address base) { _stack_base = base; }
+  size_t  stack_size() const           { return _stack_size; }
+  void    set_stack_size(size_t size)  { _stack_size = size; }
+  void    record_stack_base_and_size();
+
+  int     lgrp_id() const                 { return _lgrp_id; }
+  void    set_lgrp_id(int value)          { _lgrp_id = value; }
+
+  // Printing
+  void print_on(outputStream* st) const;
+  void print() const { print_on(tty); }
+  virtual void print_on_error(outputStream* st, char* buf, int buflen) const;
+
+  // Debug-only code
+
+#ifdef ASSERT
+ private:
+  // Deadlock detection support for Mutex locks. List of locks own by thread.
+  Monitor *_owned_locks;
+  // Mutex::set_owner_implementation is the only place where _owned_locks is modified,
+  // thus the friendship
+  friend class Mutex;
+  friend class Monitor;
+
+ public:
+  void print_owned_locks_on(outputStream* st) const;
+  void print_owned_locks() const                 { print_owned_locks_on(tty);    }
+  Monitor * owned_locks() const                  { return _owned_locks;          }
+  bool owns_locks() const                        { return owned_locks() != NULL; }
+  bool owns_locks_but_compiled_lock() const;
+
+  // Deadlock detection
+  bool allow_allocation()                        { return _allow_allocation_count == 0; }
+#endif
+
+  void check_for_valid_safepoint_state(bool potential_vm_operation) PRODUCT_RETURN;
+
+ private:
+  volatile int _jvmti_env_iteration_count;
+
+ public:
+  void entering_jvmti_env_iteration()            { ++_jvmti_env_iteration_count; }
+  void leaving_jvmti_env_iteration()             { --_jvmti_env_iteration_count; }
+  bool is_inside_jvmti_env_iteration()           { return _jvmti_env_iteration_count > 0; }
+
+  // Code generation
+  static ByteSize exception_file_offset()        { return byte_offset_of(Thread, _exception_file   ); }
+  static ByteSize exception_line_offset()        { return byte_offset_of(Thread, _exception_line   ); }
+  static ByteSize active_handles_offset()        { return byte_offset_of(Thread, _active_handles   ); }
+
+  static ByteSize stack_base_offset()            { return byte_offset_of(Thread, _stack_base ); }
+  static ByteSize stack_size_offset()            { return byte_offset_of(Thread, _stack_size ); }
+  static ByteSize omFreeList_offset()            { return byte_offset_of(Thread, omFreeList); }
+
+#define TLAB_FIELD_OFFSET(name) \
+  static ByteSize tlab_##name##_offset()            { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::name##_offset(); }
+
+  TLAB_FIELD_OFFSET(start)
+  TLAB_FIELD_OFFSET(end)
+  TLAB_FIELD_OFFSET(top)
+  TLAB_FIELD_OFFSET(pf_top)
+  TLAB_FIELD_OFFSET(size)                   // desired_size
+  TLAB_FIELD_OFFSET(refill_waste_limit)
+  TLAB_FIELD_OFFSET(number_of_refills)
+  TLAB_FIELD_OFFSET(fast_refill_waste)
+  TLAB_FIELD_OFFSET(slow_allocations)
+
+#undef TLAB_FIELD_OFFSET
+
+ public:
+  volatile intptr_t _Stalled ;
+  volatile int _TypeTag ;
+  ParkEvent * _ParkEvent ;                     // for synchronized()
+  ParkEvent * _SleepEvent ;                    // for Thread.sleep
+  ParkEvent * _MutexEvent ;                    // for native internal Mutex/Monitor
+  ParkEvent * _MuxEvent ;                      // for low-level muxAcquire-muxRelease
+  int NativeSyncRecursion ;                    // diagnostic
+
+  volatile int _OnTrap ;                       // Resume-at IP delta
+  jint _hashStateW ;                           // Marsaglia Shift-XOR thread-local RNG
+  jint _hashStateX ;                           // thread-specific hashCode generator state
+  jint _hashStateY ;
+  jint _hashStateZ ;
+  void * _schedctl ;
+
+  intptr_t _ScratchA, _ScratchB ;              // Scratch locations for fast-path sync code
+  static ByteSize ScratchA_offset()            { return byte_offset_of(Thread, _ScratchA ); }
+  static ByteSize ScratchB_offset()            { return byte_offset_of(Thread, _ScratchB ); }
+
+  volatile jint rng [4] ;                      // RNG for spin loop
+
+  // Low-level leaf-lock primitives used to implement synchronization
+  // and native monitor-mutex infrastructure.
+  // Not for general synchronization use.
+  static void SpinAcquire (volatile int * Lock, const char * Name) ;
+  static void SpinRelease (volatile int * Lock) ;
+  static void muxAcquire  (volatile intptr_t * Lock, const char * Name) ;
+  static void muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) ;
+  static void muxRelease  (volatile intptr_t * Lock) ;
+
+};
+
+// Inline implementation of Thread::current()
+// Thread::current is "hot" it's called > 128K times in the 1st 500 msecs of
+// startup.
+// ThreadLocalStorage::thread is warm -- it's called > 16K times in the same
+// period.   This is inlined in thread_<os_family>.inline.hpp.
+
+inline Thread* Thread::current() {
+#ifdef ASSERT
+// This function is very high traffic. Define PARANOID to enable expensive
+// asserts.
+#ifdef PARANOID
+  // Signal handler should call ThreadLocalStorage::get_thread_slow()
+  Thread* t = ThreadLocalStorage::get_thread_slow();
+  assert(t != NULL && !t->is_inside_signal_handler(),
+         "Don't use Thread::current() inside signal handler");
+#endif
+#endif
+  Thread* thread = ThreadLocalStorage::thread();
+  assert(thread != NULL, "just checking");
+  return thread;
+}
+
+// Name support for threads.  non-JavaThread subclasses with multiple
+// uniquely named instances should derive from this.
+class NamedThread: public Thread {
+  friend class VMStructs;
+  enum {
+    max_name_len = 64
+  };
+ private:
+  char* _name;
+ public:
+  NamedThread();
+  ~NamedThread();
+  // May only be called once per thread.
+  void set_name(const char* format, ...);
+  virtual char* name() const { return _name == NULL ? (char*)"Unknown Thread" : _name; }
+};
+
+// Worker threads are named and have an id of an assigned work.
+class WorkerThread: public NamedThread {
+private:
+  uint _id;
+public:
+  WorkerThread() : _id(0) { }
+  void set_id(uint work_id) { _id = work_id; }
+  uint id() const { return _id; }
+};
+
+// A single WatcherThread is used for simulating timer interrupts.
+class WatcherThread: public Thread {
+  friend class VMStructs;
+ public:
+  virtual void run();
+
+ private:
+  static WatcherThread* _watcher_thread;
+
+  static bool _should_terminate;
+ public:
+  enum SomeConstants {
+    delay_interval = 10                          // interrupt delay in milliseconds
+  };
+
+  // Constructor
+  WatcherThread();
+
+  // Tester
+  bool is_Watcher_thread() const                 { return true; }
+
+  // Printing
+  char* name() const { return (char*)"VM Periodic Task Thread"; }
+  void print_on(outputStream* st) const;
+  void print() const { print_on(tty); }
+
+  // Returns the single instance of WatcherThread
+  static WatcherThread* watcher_thread()         { return _watcher_thread; }
+
+  // Create and start the single instance of WatcherThread, or stop it on shutdown
+  static void start();
+  static void stop();
+};
+
+
+class CompilerThread;
+
+typedef void (*ThreadFunction)(JavaThread*, TRAPS);
+
+class JavaThread: public Thread {
+  friend class VMStructs;
+ private:
+  JavaThread*    _next;                          // The next thread in the Threads list
+  oop            _threadObj;                     // The Java level thread object
+
+#ifdef ASSERT
+ private:
+  int _java_call_counter;
+
+ public:
+  int  java_call_counter()                       { return _java_call_counter; }
+  void inc_java_call_counter()                   { _java_call_counter++; }
+  void dec_java_call_counter() {
+    assert(_java_call_counter > 0, "Invalid nesting of JavaCallWrapper");
+    _java_call_counter--;
+  }
+ private:  // restore original namespace restriction
+#endif  // ifdef ASSERT
+
+#ifndef PRODUCT
+ public:
+  enum {
+    jump_ring_buffer_size = 16
+  };
+ private:  // restore original namespace restriction
+#endif
+
+  JavaFrameAnchor _anchor;                       // Encapsulation of current java frame and it state
+
+  ThreadFunction _entry_point;
+
+  JNIEnv        _jni_environment;
+
+  // Deopt support
+  DeoptResourceMark*  _deopt_mark;               // Holds special ResourceMark for deoptimization
+
+  intptr_t*      _must_deopt_id;                 // id of frame that needs to be deopted once we
+                                                 // transition out of native
+
+  vframeArray*  _vframe_array_head;              // Holds the heap of the active vframeArrays
+  vframeArray*  _vframe_array_last;              // Holds last vFrameArray we popped
+  // Because deoptimization is lazy we must save jvmti requests to set locals
+  // in compiled frames until we deoptimize and we have an interpreter frame.
+  // This holds the pointer to array (yeah like there might be more than one) of
+  // description of compiled vframes that have locals that need to be updated.
+  GrowableArray<jvmtiDeferredLocalVariableSet*>* _deferred_locals_updates;
+
+  // Handshake value for fixing 6243940. We need a place for the i2c
+  // adapter to store the callee methodOop. This value is NEVER live
+  // across a gc point so it does NOT have to be gc'd
+  // The handshake is open ended since we can't be certain that it will
+  // be NULLed. This is because we rarely ever see the race and end up
+  // in handle_wrong_method which is the backend of the handshake. See
+  // code in i2c adapters and handle_wrong_method.
+
+  methodOop     _callee_target;
+
+  // Oop results of VM runtime calls
+  oop           _vm_result;                      // Used to pass back an oop result into Java code, GC-preserved
+  oop           _vm_result_2;                    // Used to pass back an oop result into Java code, GC-preserved
+
+  MonitorChunk* _monitor_chunks;                 // Contains the off stack monitors
+                                                 // allocated during deoptimization
+                                                 // and by JNI_MonitorEnter/Exit
+
+  // Async. requests support
+  enum AsyncRequests {
+    _no_async_condition = 0,
+    _async_exception,
+    _async_unsafe_access_error
+  };
+  AsyncRequests _special_runtime_exit_condition; // Enum indicating pending async. request
+  oop           _pending_async_exception;
+
+  // Safepoint support
+ public:                                         // Expose _thread_state for SafeFetchInt()
+  volatile JavaThreadState _thread_state;
+ private:
+  ThreadSafepointState *_safepoint_state;        // Holds information about a thread during a safepoint
+  address               _saved_exception_pc;     // Saved pc of instruction where last implicit exception happened
+
+  // JavaThread termination support
+  enum TerminatedTypes {
+    _not_terminated = 0xDEAD - 2,
+    _thread_exiting,                             // JavaThread::exit() has been called for this thread
+    _thread_terminated,                          // JavaThread is removed from thread list
+    _vm_exited                                   // JavaThread is still executing native code, but VM is terminated
+                                                 // only VM_Exit can set _vm_exited
+  };
+
+  // In general a JavaThread's _terminated field transitions as follows:
+  //
+  //   _not_terminated => _thread_exiting => _thread_terminated
+  //
+  // _vm_exited is a special value to cover the case of a JavaThread
+  // executing native code after the VM itself is terminated.
+  TerminatedTypes       _terminated;
+  // suspend/resume support
+  volatile bool         _suspend_equivalent;     // Suspend equivalent condition
+  jint                  _in_deopt_handler;       // count of deoptimization
+                                                 // handlers thread is in
+  volatile bool         _doing_unsafe_access;    // Thread may fault due to unsafe access
+  bool                  _do_not_unlock_if_synchronized; // Do not unlock the receiver of a synchronized method (since it was
+                                                 // never locked) when throwing an exception. Used by interpreter only.
+
+  //  Flag to mark a JNI thread in the process of attaching - See CR 6404306
+  //  This flag is never set true other than at construction, and in that case
+  //  is shortly thereafter set false
+  volatile bool _is_attaching;
+
+ public:
+  // State of the stack guard pages for this thread.
+  enum StackGuardState {
+    stack_guard_unused,         // not needed
+    stack_guard_yellow_disabled,// disabled (temporarily) after stack overflow
+    stack_guard_enabled         // enabled
+  };
+
+ private:
+
+  StackGuardState        _stack_guard_state;
+
+  // Compiler exception handling (NOTE: The _exception_oop is *NOT* the same as _pending_exception. It is
+  // used to temp. parsing values into and out of the runtime system during exception handling for compiled
+  // code)
+  volatile oop     _exception_oop;               // Exception thrown in compiled code
+  volatile address _exception_pc;                // PC where exception happened
+  volatile address _exception_handler_pc;        // PC for handler of exception
+  volatile int     _exception_stack_size;        // Size of frame where exception happened
+
+  // support for compilation
+  bool    _is_compiling;                         // is true if a compilation is active inthis thread (one compilation per thread possible)
+
+  // support for JNI critical regions
+  jint    _jni_active_critical;                  // count of entries into JNI critical region
+
+  // For deadlock detection.
+  int _depth_first_number;
+
+  // JVMTI PopFrame support
+  // This is set to popframe_pending to signal that top Java frame should be popped immediately
+  int _popframe_condition;
+
+#ifndef PRODUCT
+  int _jmp_ring_index;
+  struct {
+      // We use intptr_t instead of address so debugger doesn't try and display strings
+      intptr_t _target;
+      intptr_t _instruction;
+      const char*  _file;
+      int _line;
+  }   _jmp_ring[ jump_ring_buffer_size ];
+#endif /* PRODUCT */
+
+  friend class VMThread;
+  friend class ThreadWaitTransition;
+  friend class VM_Exit;
+
+  void initialize();                             // Initialized the instance variables
+
+ public:
+  // Constructor
+  JavaThread(bool is_attaching = false); // for main thread and JNI attached threads
+  JavaThread(ThreadFunction entry_point, size_t stack_size = 0);
+  ~JavaThread();
+
+#ifdef ASSERT
+  // verify this JavaThread hasn't be published in the Threads::list yet
+  void verify_not_published();
+#endif
+
+  //JNI functiontable getter/setter for JVMTI jni function table interception API.
+  void set_jni_functions(struct JNINativeInterface_* functionTable) {
+    _jni_environment.functions = functionTable;
+  }
+  struct JNINativeInterface_* get_jni_functions() {
+    return (struct JNINativeInterface_ *)_jni_environment.functions;
+  }
+
+  // Executes Shutdown.shutdown()
+  void invoke_shutdown_hooks();
+
+  // Cleanup on thread exit
+  enum ExitType {
+    normal_exit,
+    jni_detach
+  };
+  void exit(bool destroy_vm, ExitType exit_type = normal_exit);
+
+  void cleanup_failed_attach_current_thread();
+
+  // Testers
+  virtual bool is_Java_thread() const            { return true;  }
+
+  // compilation
+  void set_is_compiling(bool f)                  { _is_compiling = f; }
+  bool is_compiling() const                      { return _is_compiling; }
+
+  // Thread chain operations
+  JavaThread* next() const                       { return _next; }
+  void set_next(JavaThread* p)                   { _next = p; }
+
+  // Thread oop. threadObj() can be NULL for initial JavaThread
+  // (or for threads attached via JNI)
+  oop threadObj() const                          { return _threadObj; }
+  void set_threadObj(oop p)                      { _threadObj = p; }
+
+  ThreadPriority java_priority() const;          // Read from threadObj()
+
+  // Prepare thread and add to priority queue.  If a priority is
+  // not specified, use the priority of the thread object. Threads_lock
+  // must be held while this function is called.
+  void prepare(jobject jni_thread, ThreadPriority prio=NoPriority);
+
+  void set_saved_exception_pc(address pc)        { _saved_exception_pc = pc; }
+  address saved_exception_pc()                   { return _saved_exception_pc; }
+
+
+  ThreadFunction entry_point() const             { return _entry_point; }
+
+  // Allocates a new Java level thread object for this thread. thread_name may be NULL.
+  void allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS);
+
+  // Last frame anchor routines
+
+  JavaFrameAnchor* frame_anchor(void)                { return &_anchor; }
+
+  // last_Java_sp
+  bool has_last_Java_frame() const                   { return _anchor.has_last_Java_frame(); }
+  intptr_t* last_Java_sp() const                     { return _anchor.last_Java_sp(); }
+
+  // last_Java_pc
+
+  address last_Java_pc(void)                         { return _anchor.last_Java_pc(); }
+
+  // Safepoint support
+  JavaThreadState thread_state() const           { return _thread_state; }
+  void set_thread_state(JavaThreadState s)       { _thread_state=s;      }
+  ThreadSafepointState *safepoint_state() const  { return _safepoint_state;  }
+  void set_safepoint_state(ThreadSafepointState *state) { _safepoint_state = state; }
+  bool is_at_poll_safepoint()                    { return _safepoint_state->is_at_poll_safepoint(); }
+
+  // thread has called JavaThread::exit() or is terminated
+  bool is_exiting()                              { return _terminated == _thread_exiting || is_terminated(); }
+  // thread is terminated (no longer on the threads list); we compare
+  // against the two non-terminated values so that a freed JavaThread
+  // will also be considered terminated.
+  bool is_terminated()                           { return _terminated != _not_terminated && _terminated != _thread_exiting; }
+  void set_terminated(TerminatedTypes t)         { _terminated = t; }
+  // special for Threads::remove() which is static:
+  void set_terminated_value()                    { _terminated = _thread_terminated; }
+  void block_if_vm_exited();
+
+  bool doing_unsafe_access()                     { return _doing_unsafe_access; }
+  void set_doing_unsafe_access(bool val)         { _doing_unsafe_access = val; }
+
+  bool do_not_unlock_if_synchronized()             { return _do_not_unlock_if_synchronized; }
+  void set_do_not_unlock_if_synchronized(bool val) { _do_not_unlock_if_synchronized = val; }
+
+
+  // Suspend/resume support for JavaThread
+
+ private:
+  void set_ext_suspended()       { set_suspend_flag (_ext_suspended);  }
+  void clear_ext_suspended()     { clear_suspend_flag(_ext_suspended); }
+
+ public:
+  void java_suspend();
+  void java_resume();
+  int  java_suspend_self();
+
+  void check_and_wait_while_suspended() {
+    assert(JavaThread::current() == this, "sanity check");
+
+    bool do_self_suspend;
+    do {
+      // were we externally suspended while we were waiting?
+      do_self_suspend = handle_special_suspend_equivalent_condition();
+      if (do_self_suspend) {
+        // don't surprise the thread that suspended us by returning
+        java_suspend_self();
+        set_suspend_equivalent();
+      }
+    } while (do_self_suspend);
+  }
+  static void check_safepoint_and_suspend_for_native_trans(JavaThread *thread);
+  // Check for async exception in addition to safepoint and suspend request.
+  static void check_special_condition_for_native_trans(JavaThread *thread);
+
+  bool is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits);
+  bool is_ext_suspend_completed_with_lock(uint32_t *bits) {
+    MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
+    // Warning: is_ext_suspend_completed() may temporarily drop the
+    // SR_lock to allow the thread to reach a stable thread state if
+    // it is currently in a transient thread state.
+    return is_ext_suspend_completed(false /*!called_by_wait */,
+                                    SuspendRetryDelay, bits);
+  }
+
+  // We cannot allow wait_for_ext_suspend_completion() to run forever or
+  // we could hang. SuspendRetryCount and SuspendRetryDelay are normally
+  // passed as the count and delay parameters. Experiments with specific
+  // calls to wait_for_ext_suspend_completion() can be done by passing
+  // other values in the code. Experiments with all calls can be done
+  // via the appropriate -XX options.
+  bool wait_for_ext_suspend_completion(int count, int delay, uint32_t *bits);
+
+  void set_external_suspend()     { set_suspend_flag  (_external_suspend); }
+  void clear_external_suspend()   { clear_suspend_flag(_external_suspend); }
+
+  void set_deopt_suspend()        { set_suspend_flag  (_deopt_suspend); }
+  void clear_deopt_suspend()      { clear_suspend_flag(_deopt_suspend); }
+  bool is_deopt_suspend()         { return (_suspend_flags & _deopt_suspend) != 0; }
+
+  bool is_external_suspend() const {
+    return (_suspend_flags & _external_suspend) != 0;
+  }
+  // Whenever a thread transitions from native to vm/java it must suspend
+  // if external|deopt suspend is present.
+  bool is_suspend_after_native() const {
+    return (_suspend_flags & (_external_suspend | _deopt_suspend) ) != 0;
+  }
+
+  // external suspend request is completed
+  bool is_ext_suspended() const {
+    return (_suspend_flags & _ext_suspended) != 0;
+  }
+
+  // legacy method that checked for either external suspension or vm suspension
+  bool is_any_suspended() const {
+    return is_ext_suspended();
+  }
+
+  bool is_external_suspend_with_lock() const {
+    MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
+    return is_external_suspend();
+  }
+
+  // Special method to handle a pending external suspend request
+  // when a suspend equivalent condition lifts.
+  bool handle_special_suspend_equivalent_condition() {
+    assert(is_suspend_equivalent(),
+      "should only be called in a suspend equivalence condition");
+    MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
+    bool ret = is_external_suspend();
+    if (!ret) {
+      // not about to self-suspend so clear suspend equivalence
+      clear_suspend_equivalent();
+    }
+    // implied else:
+    // We have a pending external suspend request so we leave the
+    // suspend_equivalent flag set until java_suspend_self() sets
+    // the ext_suspended flag and clears the suspend_equivalent
+    // flag. This insures that wait_for_ext_suspend_completion()
+    // will return consistent values.
+    return ret;
+  }
+
+  bool is_any_suspended_with_lock() const {
+    MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
+    return is_any_suspended();
+  }
+  // utility methods to see if we are doing some kind of suspension
+  bool is_being_ext_suspended() const            {
+    MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
+    return is_ext_suspended() || is_external_suspend();
+  }
+
+  bool is_suspend_equivalent() const             { return _suspend_equivalent; }
+
+  void set_suspend_equivalent()                  { _suspend_equivalent = true; };
+  void clear_suspend_equivalent()                { _suspend_equivalent = false; };
+
+  // Thread.stop support
+  void send_thread_stop(oop throwable);
+  AsyncRequests clear_special_runtime_exit_condition() {
+    AsyncRequests x = _special_runtime_exit_condition;
+    _special_runtime_exit_condition = _no_async_condition;
+    return x;
+  }
+
+  // Are any async conditions present?
+  bool has_async_condition() { return (_special_runtime_exit_condition != _no_async_condition); }
+
+  void check_and_handle_async_exceptions(bool check_unsafe_error = true);
+
+  // these next two are also used for self-suspension and async exception support
+  void handle_special_runtime_exit_condition(bool check_asyncs = true);
+
+  // Return true if JavaThread has an asynchronous condition or
+  // if external suspension is requested.
+  bool has_special_runtime_exit_condition() {
+    // We call is_external_suspend() last since external suspend should
+    // be less common. Because we don't use is_external_suspend_with_lock
+    // it is possible that we won't see an asynchronous external suspend
+    // request that has just gotten started, i.e., SR_lock grabbed but
+    // _external_suspend field change either not made yet or not visible
+    // yet. However, this is okay because the request is asynchronous and
+    // we will see the new flag value the next time through. It's also
+    // possible that the external suspend request is dropped after
+    // we have checked is_external_suspend(), we will recheck its value
+    // under SR_lock in java_suspend_self().
+    return (_special_runtime_exit_condition != _no_async_condition) ||
+            is_external_suspend() || is_deopt_suspend();
+  }
+
+  void set_pending_unsafe_access_error()          { _special_runtime_exit_condition = _async_unsafe_access_error; }
+
+  void set_pending_async_exception(oop e) {
+    _pending_async_exception = e;
+    _special_runtime_exit_condition = _async_exception;
+    set_has_async_exception();
+  }
+
+  // Fast-locking support
+  bool is_lock_owned(address adr) const;
+
+  // Accessors for vframe array top
+  // The linked list of vframe arrays are sorted on sp. This means when we
+  // unpack the head must contain the vframe array to unpack.
+  void set_vframe_array_head(vframeArray* value) { _vframe_array_head = value; }
+  vframeArray* vframe_array_head() const         { return _vframe_array_head;  }
+
+  // Side structure for defering update of java frame locals until deopt occurs
+  GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred_locals() const { return _deferred_locals_updates; }
+  void set_deferred_locals(GrowableArray<jvmtiDeferredLocalVariableSet *>* vf) { _deferred_locals_updates = vf; }
+
+  // These only really exist to make debugging deopt problems simpler
+
+  void set_vframe_array_last(vframeArray* value) { _vframe_array_last = value; }
+  vframeArray* vframe_array_last() const         { return _vframe_array_last;  }
+
+  // The special resourceMark used during deoptimization
+
+  void set_deopt_mark(DeoptResourceMark* value)  { _deopt_mark = value; }
+  DeoptResourceMark* deopt_mark(void)            { return _deopt_mark; }
+
+  intptr_t* must_deopt_id()                      { return _must_deopt_id; }
+  void     set_must_deopt_id(intptr_t* id)       { _must_deopt_id = id; }
+  void     clear_must_deopt_id()                 { _must_deopt_id = NULL; }
+
+  methodOop  callee_target() const               { return _callee_target; }
+  void set_callee_target  (methodOop x)          { _callee_target   = x; }
+
+  // Oop results of vm runtime calls
+  oop  vm_result() const                         { return _vm_result; }
+  void set_vm_result  (oop x)                    { _vm_result   = x; }
+
+  oop  vm_result_2() const                       { return _vm_result_2; }
+  void set_vm_result_2  (oop x)                  { _vm_result_2   = x; }
+
+  // Exception handling for compiled methods
+  oop      exception_oop() const                 { return _exception_oop; }
+  int      exception_stack_size() const          { return _exception_stack_size; }
+  address  exception_pc() const                  { return _exception_pc; }
+  address  exception_handler_pc() const          { return _exception_handler_pc; }
+
+  void set_exception_oop(oop o)                  { _exception_oop = o; }
+  void set_exception_pc(address a)               { _exception_pc = a; }
+  void set_exception_handler_pc(address a)       { _exception_handler_pc = a; }
+  void set_exception_stack_size(int size)        { _exception_stack_size = size; }
+
+  // Stack overflow support
+  inline size_t stack_available(address cur_sp);
+  address stack_yellow_zone_base()
+    { return (address)(stack_base() - (stack_size() - (stack_red_zone_size() + stack_yellow_zone_size()))); }
+  size_t  stack_yellow_zone_size()
+    { return StackYellowPages * os::vm_page_size(); }
+  address stack_red_zone_base()
+    { return (address)(stack_base() - (stack_size() - stack_red_zone_size())); }
+  size_t stack_red_zone_size()
+    { return StackRedPages * os::vm_page_size(); }
+  bool in_stack_yellow_zone(address a)
+    { return (a <= stack_yellow_zone_base()) && (a >= stack_red_zone_base()); }
+  bool in_stack_red_zone(address a)
+    { return (a <= stack_red_zone_base()) && (a >= (address)((intptr_t)stack_base() - stack_size())); }
+
+  void create_stack_guard_pages();
+  void remove_stack_guard_pages();
+
+  void enable_stack_yellow_zone();
+  void disable_stack_yellow_zone();
+  void enable_stack_red_zone();
+  void disable_stack_red_zone();
+
+  inline bool stack_yellow_zone_disabled();
+  inline bool stack_yellow_zone_enabled();
+
+  // Attempt to reguard the stack after a stack overflow may have occurred.
+  // Returns true if (a) guard pages are not needed on this thread, (b) the
+  // pages are already guarded, or (c) the pages were successfully reguarded.
+  // Returns false if there is not enough stack space to reguard the pages, in
+  // which case the caller should unwind a frame and try again.  The argument
+  // should be the caller's (approximate) sp.
+  bool reguard_stack(address cur_sp);
+  // Similar to above but see if current stackpoint is out of the guard area
+  // and reguard if possible.
+  bool reguard_stack(void);
+
+  // Misc. accessors/mutators
+  void set_do_not_unlock(void)                   { _do_not_unlock_if_synchronized = true; }
+  void clr_do_not_unlock(void)                   { _do_not_unlock_if_synchronized = false; }
+  bool do_not_unlock(void)                       { return _do_not_unlock_if_synchronized; }
+
+#ifndef PRODUCT
+  void record_jump(address target, address instr, const char* file, int line);
+#endif /* PRODUCT */
+
+  // For assembly stub generation
+  static ByteSize threadObj_offset()             { return byte_offset_of(JavaThread, _threadObj           ); }
+#ifndef PRODUCT
+  static ByteSize jmp_ring_index_offset()        { return byte_offset_of(JavaThread, _jmp_ring_index      ); }
+  static ByteSize jmp_ring_offset()              { return byte_offset_of(JavaThread, _jmp_ring            ); }
+#endif /* PRODUCT */
+  static ByteSize jni_environment_offset()       { return byte_offset_of(JavaThread, _jni_environment     ); }
+  static ByteSize last_Java_sp_offset()          {
+    return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_sp_offset();
+  }
+  static ByteSize last_Java_pc_offset()          {
+    return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_pc_offset();
+  }
+  static ByteSize frame_anchor_offset()          {
+    return byte_offset_of(JavaThread, _anchor);
+  }
+  static ByteSize callee_target_offset()         { return byte_offset_of(JavaThread, _callee_target       ); }
+  static ByteSize vm_result_offset()             { return byte_offset_of(JavaThread, _vm_result           ); }
+  static ByteSize vm_result_2_offset()           { return byte_offset_of(JavaThread, _vm_result_2         ); }
+  static ByteSize thread_state_offset()          { return byte_offset_of(JavaThread, _thread_state        ); }
+  static ByteSize saved_exception_pc_offset()    { return byte_offset_of(JavaThread, _saved_exception_pc  ); }
+  static ByteSize osthread_offset()              { return byte_offset_of(JavaThread, _osthread            ); }
+  static ByteSize exception_oop_offset()         { return byte_offset_of(JavaThread, _exception_oop       ); }
+  static ByteSize exception_pc_offset()          { return byte_offset_of(JavaThread, _exception_pc        ); }
+  static ByteSize exception_handler_pc_offset()  { return byte_offset_of(JavaThread, _exception_handler_pc); }
+  static ByteSize exception_stack_size_offset()  { return byte_offset_of(JavaThread, _exception_stack_size); }
+  static ByteSize stack_guard_state_offset()     { return byte_offset_of(JavaThread, _stack_guard_state   ); }
+  static ByteSize suspend_flags_offset()         { return byte_offset_of(JavaThread, _suspend_flags       ); }
+
+  static ByteSize do_not_unlock_if_synchronized_offset() { return byte_offset_of(JavaThread, _do_not_unlock_if_synchronized); }
+
+  // Returns the jni environment for this thread
+  JNIEnv* jni_environment()                      { return &_jni_environment; }
+
+  static JavaThread* thread_from_jni_environment(JNIEnv* env) {
+    JavaThread *thread_from_jni_env = (JavaThread*)((intptr_t)env - in_bytes(jni_environment_offset()));
+    // Only return NULL if thread is off the thread list; starting to
+    // exit should not return NULL.
+    if (thread_from_jni_env->is_terminated()) {
+       thread_from_jni_env->block_if_vm_exited();
+       return NULL;
+    } else {
+       return thread_from_jni_env;
+    }
+  }
+
+  // JNI critical regions. These can nest.
+  bool in_critical()    { return _jni_active_critical > 0; }
+  void enter_critical() { assert(Thread::current() == this,
+                                 "this must be current thread");
+                          _jni_active_critical++; }
+  void exit_critical()  { assert(Thread::current() == this,
+                                 "this must be current thread");
+                          _jni_active_critical--;
+                          assert(_jni_active_critical >= 0,
+                                 "JNI critical nesting problem?"); }
+
+  // For deadlock detection
+  int depth_first_number() { return _depth_first_number; }
+  void set_depth_first_number(int dfn) { _depth_first_number = dfn; }
+
+ private:
+  void set_monitor_chunks(MonitorChunk* monitor_chunks) { _monitor_chunks = monitor_chunks; }
+
+ public:
+  MonitorChunk* monitor_chunks() const           { return _monitor_chunks; }
+  void add_monitor_chunk(MonitorChunk* chunk);
+  void remove_monitor_chunk(MonitorChunk* chunk);
+  bool in_deopt_handler() const                  { return _in_deopt_handler > 0; }
+  void inc_in_deopt_handler()                    { _in_deopt_handler++; }
+  void dec_in_deopt_handler()                    {
+    assert(_in_deopt_handler > 0, "mismatched deopt nesting");
+    if (_in_deopt_handler > 0) { // robustness
+      _in_deopt_handler--;
+    }
+  }
+
+ private:
+  void set_entry_point(ThreadFunction entry_point) { _entry_point = entry_point; }
+
+ public:
+
+  // Frame iteration; calls the function f for all frames on the stack
+  void frames_do(void f(frame*, const RegisterMap*));
+
+  // Memory operations
+  void oops_do(OopClosure* f);
+
+  // Sweeper operations
+  void nmethods_do();
+
+  // Memory management operations
+  void gc_epilogue();
+  void gc_prologue();
+
+  // Misc. operations
+  char* name() const { return (char*)get_thread_name(); }
+  void print_on(outputStream* st) const;
+  void print() const { print_on(tty); }
+  void print_value();
+  void print_thread_state_on(outputStream* ) const      PRODUCT_RETURN;
+  void print_thread_state() const                       PRODUCT_RETURN;
+  void print_on_error(outputStream* st, char* buf, int buflen) const;
+  void verify();
+  const char* get_thread_name() const;
+private:
+  // factor out low-level mechanics for use in both normal and error cases
+  const char* get_thread_name_string(char* buf = NULL, int buflen = 0) const;
+public:
+  const char* get_threadgroup_name() const;
+  const char* get_parent_name() const;
+
+  // Accessing frames
+  frame last_frame() {
+    _anchor.make_walkable(this);
+    return pd_last_frame();
+  }
+  javaVFrame* last_java_vframe(RegisterMap* reg_map);
+
+  // Returns method at 'depth' java or native frames down the stack
+  // Used for security checks
+  klassOop security_get_caller_class(int depth);
+
+  // Print stack trace in external format
+  void print_stack_on(outputStream* st);
+  void print_stack() { print_stack_on(tty); }
+
+  // Print stack traces in various internal formats
+  void trace_stack()                             PRODUCT_RETURN;
+  void trace_stack_from(vframe* start_vf)        PRODUCT_RETURN;
+  void trace_frames()                            PRODUCT_RETURN;
+
+  // Returns the number of stack frames on the stack
+  int depth() const;
+
+  // Function for testing deoptimization
+  void deoptimize();
+  void make_zombies();
+
+  void deoptimized_wrt_marked_nmethods();
+
+  // Profiling operation (see fprofile.cpp)
+ public:
+   bool profile_last_Java_frame(frame* fr);
+
+ private:
+   ThreadProfiler* _thread_profiler;
+ private:
+   friend class FlatProfiler;                    // uses both [gs]et_thread_profiler.
+   friend class FlatProfilerTask;                // uses get_thread_profiler.
+   friend class ThreadProfilerMark;              // uses get_thread_profiler.
+   ThreadProfiler* get_thread_profiler()         { return _thread_profiler; }
+   ThreadProfiler* set_thread_profiler(ThreadProfiler* tp) {
+     ThreadProfiler* result = _thread_profiler;
+     _thread_profiler = tp;
+     return result;
+   }
+
+  // Static operations
+ public:
+  // Returns the running thread as a JavaThread
+  static inline JavaThread* current();
+
+  // Returns the active Java thread.  Do not use this if you know you are calling
+  // from a JavaThread, as it's slower than JavaThread::current.  If called from
+  // the VMThread, it also returns the JavaThread that instigated the VMThread's
+  // operation.  You may not want that either.
+  static JavaThread* active();
+
+  inline CompilerThread* as_CompilerThread();
+
+ public:
+  virtual void run();
+  void thread_main_inner();
+
+ private:
+  // PRIVILEGED STACK
+  PrivilegedElement*  _privileged_stack_top;
+  GrowableArray<oop>* _array_for_gc;
+ public:
+
+  // Returns the privileged_stack information.
+  PrivilegedElement* privileged_stack_top() const       { return _privileged_stack_top; }
+  void set_privileged_stack_top(PrivilegedElement *e)   { _privileged_stack_top = e; }
+  void register_array_for_gc(GrowableArray<oop>* array) { _array_for_gc = array; }
+
+ public:
+  // Thread local information maintained by JVMTI.
+  void set_jvmti_thread_state(JvmtiThreadState *value)                           { _jvmti_thread_state = value; }
+  JvmtiThreadState *jvmti_thread_state() const                                   { return _jvmti_thread_state; }
+  static ByteSize jvmti_thread_state_offset()                                    { return byte_offset_of(JavaThread, _jvmti_thread_state); }
+  void set_jvmti_get_loaded_classes_closure(JvmtiGetLoadedClassesClosure* value) { _jvmti_get_loaded_classes_closure = value; }
+  JvmtiGetLoadedClassesClosure* get_jvmti_get_loaded_classes_closure() const     { return _jvmti_get_loaded_classes_closure; }
+
+  // JVMTI PopFrame support
+  // Setting and clearing popframe_condition
+  // All of these enumerated values are bits. popframe_pending
+  // indicates that a PopFrame() has been requested and not yet been
+  // completed. popframe_processing indicates that that PopFrame() is in
+  // the process of being completed. popframe_force_deopt_reexecution_bit
+  // indicates that special handling is required when returning to a
+  // deoptimized caller.
+  enum PopCondition {
+    popframe_inactive                      = 0x00,
+    popframe_pending_bit                   = 0x01,
+    popframe_processing_bit                = 0x02,
+    popframe_force_deopt_reexecution_bit   = 0x04
+  };
+  PopCondition popframe_condition()                   { return (PopCondition) _popframe_condition; }
+  void set_popframe_condition(PopCondition c)         { _popframe_condition = c; }
+  void set_popframe_condition_bit(PopCondition c)     { _popframe_condition |= c; }
+  void clear_popframe_condition()                     { _popframe_condition = popframe_inactive; }
+  static ByteSize popframe_condition_offset()         { return byte_offset_of(JavaThread, _popframe_condition); }
+  bool has_pending_popframe()                         { return (popframe_condition() & popframe_pending_bit) != 0; }
+  bool popframe_forcing_deopt_reexecution()           { return (popframe_condition() & popframe_force_deopt_reexecution_bit) != 0; }
+  void clear_popframe_forcing_deopt_reexecution()     { _popframe_condition &= ~popframe_force_deopt_reexecution_bit; }
+#ifdef CC_INTERP
+  bool pop_frame_pending(void)                        { return ((_popframe_condition & popframe_pending_bit) != 0); }
+  void clr_pop_frame_pending(void)                    { _popframe_condition = popframe_inactive; }
+  bool pop_frame_in_process(void)                     { return ((_popframe_condition & popframe_processing_bit) != 0); }
+  void set_pop_frame_in_process(void)                 { _popframe_condition |= popframe_processing_bit; }
+  void clr_pop_frame_in_process(void)                 { _popframe_condition &= ~popframe_processing_bit; }
+#endif
+
+ private:
+  // Saved incoming arguments to popped frame.
+  // Used only when popped interpreted frame returns to deoptimized frame.
+  void*    _popframe_preserved_args;
+  int      _popframe_preserved_args_size;
+
+ public:
+  void  popframe_preserve_args(ByteSize size_in_bytes, void* start);
+  void* popframe_preserved_args();
+  ByteSize popframe_preserved_args_size();
+  WordSize popframe_preserved_args_size_in_words();
+  void  popframe_free_preserved_args();
+
+
+ private:
+  JvmtiThreadState *_jvmti_thread_state;
+  JvmtiGetLoadedClassesClosure* _jvmti_get_loaded_classes_closure;
+
+  // Used by the interpreter in fullspeed mode for frame pop, method
+  // entry, method exit and single stepping support. This field is
+  // only set to non-zero by the VM_EnterInterpOnlyMode VM operation.
+  // It can be set to zero asynchronously (i.e., without a VM operation
+  // or a lock) so we have to be very careful.
+  int               _interp_only_mode;
+
+ public:
+  // used by the interpreter for fullspeed debugging support (see above)
+  static ByteSize interp_only_mode_offset() { return byte_offset_of(JavaThread, _interp_only_mode); }
+  bool is_interp_only_mode()                { return (_interp_only_mode != 0); }
+  int get_interp_only_mode()                { return _interp_only_mode; }
+  void increment_interp_only_mode()         { ++_interp_only_mode; }
+  void decrement_interp_only_mode()         { --_interp_only_mode; }
+
+ private:
+  ThreadStatistics *_thread_stat;
+
+ public:
+  ThreadStatistics* get_thread_stat() const    { return _thread_stat; }
+
+  // Return a blocker object for which this thread is blocked parking.
+  oop current_park_blocker();
+
+ private:
+  static size_t _stack_size_at_create;
+
+ public:
+  static inline size_t stack_size_at_create(void) {
+    return _stack_size_at_create;
+  }
+  static inline void set_stack_size_at_create(size_t value) {
+    _stack_size_at_create = value;
+  }
+
+  // Machine dependent stuff
+  #include "incls/_thread_pd.hpp.incl"
+
+ public:
+  void set_blocked_on_compilation(bool value) {
+    _blocked_on_compilation = value;
+  }
+
+  bool blocked_on_compilation() {
+    return _blocked_on_compilation;
+  }
+ protected:
+  bool         _blocked_on_compilation;
+
+
+  // JSR166 per-thread parker
+private:
+  Parker*    _parker;
+public:
+  Parker*     parker() { return _parker; }
+
+  // Biased locking support
+private:
+  GrowableArray<MonitorInfo*>* _cached_monitor_info;
+public:
+  GrowableArray<MonitorInfo*>* cached_monitor_info() { return _cached_monitor_info; }
+  void set_cached_monitor_info(GrowableArray<MonitorInfo*>* info) { _cached_monitor_info = info; }
+
+  // clearing/querying jni attach status
+  bool is_attaching() const { return _is_attaching; }
+  void set_attached() { _is_attaching = false; OrderAccess::fence(); }
+};
+
+// Inline implementation of JavaThread::current
+inline JavaThread* JavaThread::current() {
+  Thread* thread = ThreadLocalStorage::thread();
+  assert(thread != NULL && thread->is_Java_thread(), "just checking");
+  return (JavaThread*)thread;
+}
+
+inline CompilerThread* JavaThread::as_CompilerThread() {
+  assert(is_Compiler_thread(), "just checking");
+  return (CompilerThread*)this;
+}
+
+inline bool JavaThread::stack_yellow_zone_disabled() {
+  return _stack_guard_state == stack_guard_yellow_disabled;
+}
+
+inline bool JavaThread::stack_yellow_zone_enabled() {
+#ifdef ASSERT
+  if (os::uses_stack_guard_pages()) {
+    assert(_stack_guard_state != stack_guard_unused, "guard pages must be in use");
+  }
+#endif
+    return _stack_guard_state == stack_guard_enabled;
+}
+
+inline size_t JavaThread::stack_available(address cur_sp) {
+  // This code assumes java stacks grow down
+  address low_addr; // Limit on the address for deepest stack depth
+  if ( _stack_guard_state == stack_guard_unused) {
+    low_addr =  stack_base() - stack_size();
+  } else {
+    low_addr = stack_yellow_zone_base();
+  }
+  return cur_sp > low_addr ? cur_sp - low_addr : 0;
+}
+
+// A JavaThread for low memory detection support
+class LowMemoryDetectorThread : public JavaThread {
+  friend class VMStructs;
+public:
+  LowMemoryDetectorThread(ThreadFunction entry_point) : JavaThread(entry_point) {};
+
+  // Hide this thread from external view.
+  bool is_hidden_from_external_view() const      { return true; }
+};
+
+// A thread used for Compilation.
+class CompilerThread : public JavaThread {
+  friend class VMStructs;
+ private:
+  CompilerCounters* _counters;
+
+  ciEnv*        _env;
+  CompileLog*   _log;
+  CompileTask*  _task;
+  CompileQueue* _queue;
+
+ public:
+
+  static CompilerThread* current();
+
+  CompilerThread(CompileQueue* queue, CompilerCounters* counters);
+
+  bool is_Compiler_thread() const                { return true; }
+  // Hide this compiler thread from external view.
+  bool is_hidden_from_external_view() const      { return true; }
+
+  CompileQueue* queue()                          { return _queue; }
+  CompilerCounters* counters()                   { return _counters; }
+
+  // Get/set the thread's compilation environment.
+  ciEnv*        env()                            { return _env; }
+  void          set_env(ciEnv* env)              { _env = env; }
+
+  // Get/set the thread's logging information
+  CompileLog*   log()                            { return _log; }
+  void          init_log(CompileLog* log) {
+    // Set once, for good.
+    assert(_log == NULL, "set only once");
+    _log = log;
+  }
+
+#ifndef PRODUCT
+private:
+  IdealGraphPrinter *_ideal_graph_printer;
+public:
+  IdealGraphPrinter *ideal_graph_printer()                       { return _ideal_graph_printer; }
+  void set_ideal_graph_printer(IdealGraphPrinter *n)             { _ideal_graph_printer = n; }
+#endif
+
+  // Get/set the thread's current task
+  CompileTask*  task()                           { return _task; }
+  void          set_task(CompileTask* task)      { _task = task; }
+};
+
+inline CompilerThread* CompilerThread::current() {
+  return JavaThread::current()->as_CompilerThread();
+}
+
+
+// The active thread queue. It also keeps track of the current used
+// thread priorities.
+class Threads: AllStatic {
+  friend class VMStructs;
+ private:
+  static JavaThread* _thread_list;
+  static int         _number_of_threads;
+  static int         _number_of_non_daemon_threads;
+  static int         _return_code;
+
+ public:
+  // Thread management
+  // force_daemon is a concession to JNI, where we may need to add a
+  // thread to the thread list before allocating its thread object
+  static void add(JavaThread* p, bool force_daemon = false);
+  static void remove(JavaThread* p);
+  static bool includes(JavaThread* p);
+  static JavaThread* first()                     { return _thread_list; }
+  static void threads_do(ThreadClosure* tc);
+
+  // Initializes the vm and creates the vm thread
+  static jint create_vm(JavaVMInitArgs* args, bool* canTryAgain);
+  static void convert_vm_init_libraries_to_agents();
+  static void create_vm_init_libraries();
+  static void create_vm_init_agents();
+  static void shutdown_vm_agents();
+  static bool destroy_vm();
+  // Supported VM versions via JNI
+  // Includes JNI_VERSION_1_1
+  static jboolean is_supported_jni_version_including_1_1(jint version);
+  // Does not include JNI_VERSION_1_1
+  static jboolean is_supported_jni_version(jint version);
+
+  // Garbage collection
+  static void follow_other_roots(void f(oop*));
+
+  // Apply "f->do_oop" to all root oops in all threads.
+  // This version may only be called by sequential code.
+  static void oops_do(OopClosure* f);
+  // This version may be called by sequential or parallel code.
+  static void possibly_parallel_oops_do(OopClosure* f);
+  // This creates a list of GCTasks, one per thread.
+  static void create_thread_roots_tasks(GCTaskQueue* q);
+  // This creates a list of GCTasks, one per thread, for marking objects.
+  static void create_thread_roots_marking_tasks(GCTaskQueue* q);
+
+  // Apply "f->do_oop" to roots in all threads that
+  // are part of compiled frames
+  static void compiled_frame_oops_do(OopClosure* f);
+
+  static void convert_hcode_pointers();
+  static void restore_hcode_pointers();
+
+  // Sweeper
+  static void nmethods_do();
+
+  static void gc_epilogue();
+  static void gc_prologue();
+
+  // Verification
+  static void verify();
+  static void print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks);
+  static void print(bool print_stacks, bool internal_format) {
+    // this function is only used by debug.cpp
+    print_on(tty, print_stacks, internal_format, false /* no concurrent lock printed */);
+  }
+  static void print_on_error(outputStream* st, Thread* current, char* buf, int buflen);
+
+  // Get Java threads that are waiting to enter a monitor. If doLock
+  // is true, then Threads_lock is grabbed as needed. Otherwise, the
+  // VM needs to be at a safepoint.
+  static GrowableArray<JavaThread*>* get_pending_threads(int count,
+    address monitor, bool doLock);
+
+  // Get owning Java thread from the monitor's owner field. If doLock
+  // is true, then Threads_lock is grabbed as needed. Otherwise, the
+  // VM needs to be at a safepoint.
+  static JavaThread *owning_thread_from_monitor_owner(address owner,
+    bool doLock);
+
+  // Number of threads on the active threads list
+  static int number_of_threads()                 { return _number_of_threads; }
+  // Number of non-daemon threads on the active threads list
+  static int number_of_non_daemon_threads()      { return _number_of_non_daemon_threads; }
+
+  // Deoptimizes all frames tied to marked nmethods
+  static void deoptimized_wrt_marked_nmethods();
+
+};
+
+
+// Thread iterator
+class ThreadClosure: public StackObj {
+ public:
+  virtual void do_thread(Thread* thread) = 0;
+};
+
+class SignalHandlerMark: public StackObj {
+private:
+  Thread* _thread;
+public:
+  SignalHandlerMark(Thread* t) {
+    _thread = t;
+    if (_thread) _thread->enter_signal_handler();
+  }
+  ~SignalHandlerMark() {
+    if (_thread) _thread->leave_signal_handler();
+    _thread = NULL;
+  }
+};
+
+// ParkEvents are type-stable and immortal.
+//
+// Lifecycle: Once a ParkEvent is associated with a thread that ParkEvent remains
+// associated with the thread for the thread's entire lifetime - the relationship is
+// stable. A thread will be associated at most one ParkEvent.  When the thread
+// expires, the ParkEvent moves to the EventFreeList.  New threads attempt to allocate from
+// the EventFreeList before creating a new Event.  Type-stability frees us from
+// worrying about stale Event or Thread references in the objectMonitor subsystem.
+// (A reference to ParkEvent is always valid, even though the event may no longer be associated
+// with the desired or expected thread.  A key aspect of this design is that the callers of
+// park, unpark, etc must tolerate stale references and spurious wakeups).
+//
+// Only the "associated" thread can block (park) on the ParkEvent, although
+// any other thread can unpark a reachable parkevent.  Park() is allowed to
+// return spuriously.  In fact park-unpark a really just an optimization to
+// avoid unbounded spinning and surrender the CPU to be a polite system citizen.
+// A degenerate albeit "impolite" park-unpark implementation could simply return.
+// See http://blogs.sun.com/dave for more details.
+//
+// Eventually I'd like to eliminate Events and ObjectWaiters, both of which serve as
+// thread proxies, and simply make the THREAD structure type-stable and persistent.
+// Currently, we unpark events associated with threads, but ideally we'd just
+// unpark threads.
+//
+// The base-class, PlatformEvent, is platform-specific while the ParkEvent is
+// platform-independent.  PlatformEvent provides park(), unpark(), etc., and
+// is abstract -- that is, a PlatformEvent should never be instantiated except
+// as part of a ParkEvent.
+// Equivalently we could have defined a platform-independent base-class that
+// exported Allocate(), Release(), etc.  The platform-specific class would extend
+// that base-class, adding park(), unpark(), etc.
+//
+// A word of caution: The JVM uses 2 very similar constructs:
+// 1. ParkEvent are used for Java-level "monitor" synchronization.
+// 2. Parkers are used by JSR166-JUC park-unpark.
+//
+// We'll want to eventually merge these redundant facilities and use ParkEvent.
+
+
+class ParkEvent : public os::PlatformEvent {
+  private:
+    ParkEvent * FreeNext ;
+
+    // Current association
+    Thread * AssociatedWith ;
+    intptr_t RawThreadIdentity ;        // LWPID etc
+    volatile int Incarnation ;
+
+    // diagnostic : keep track of last thread to wake this thread.
+    // this is useful for construction of dependency graphs.
+    void * LastWaker ;
+
+  public:
+    // MCS-CLH list linkage and Native Mutex/Monitor
+    ParkEvent * volatile ListNext ;
+    ParkEvent * volatile ListPrev ;
+    volatile intptr_t OnList ;
+    volatile int TState ;
+    volatile int Notified ;             // for native monitor construct
+    volatile int IsWaiting ;            // Enqueued on WaitSet
+
+
+  private:
+    static ParkEvent * volatile FreeList ;
+    static volatile int ListLock ;
+
+    // It's prudent to mark the dtor as "private"
+    // ensuring that it's not visible outside the package.
+    // Unfortunately gcc warns about such usage, so
+    // we revert to the less desirable "protected" visibility.
+    // The other compilers accept private dtors.
+
+  protected:        // Ensure dtor is never invoked
+    ~ParkEvent() { guarantee (0, "invariant") ; }
+
+    ParkEvent() : PlatformEvent() {
+       AssociatedWith = NULL ;
+       FreeNext       = NULL ;
+       ListNext       = NULL ;
+       ListPrev       = NULL ;
+       OnList         = 0 ;
+       TState         = 0 ;
+       Notified       = 0 ;
+       IsWaiting      = 0 ;
+    }
+
+    // We use placement-new to force ParkEvent instances to be
+    // aligned on 256-byte address boundaries.  This ensures that the least
+    // significant byte of a ParkEvent address is always 0.
+
+    void * operator new (size_t sz) ;
+    void operator delete (void * a) ;
+
+  public:
+    static ParkEvent * Allocate (Thread * t) ;
+    static void Release (ParkEvent * e) ;
+} ;