JDK14/Java14源码在线阅读
/*
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* 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
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*/
#ifndef SHARE_RUNTIME_THREAD_HPP
#define SHARE_RUNTIME_THREAD_HPP
#include "jni.h"
#include "code/compiledMethod.hpp"
#include "gc/shared/gcThreadLocalData.hpp"
#include "gc/shared/threadLocalAllocBuffer.hpp"
#include "memory/allocation.hpp"
#include "oops/oop.hpp"
#include "prims/jvmtiExport.hpp"
#include "runtime/frame.hpp"
#include "runtime/globals.hpp"
#include "runtime/handshake.hpp"
#include "runtime/javaFrameAnchor.hpp"
#include "runtime/jniHandles.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/os.hpp"
#include "runtime/osThread.hpp"
#include "runtime/park.hpp"
#include "runtime/stubRoutines.hpp"
#include "runtime/threadHeapSampler.hpp"
#include "runtime/threadLocalStorage.hpp"
#include "runtime/threadStatisticalInfo.hpp"
#include "runtime/unhandledOops.hpp"
#include "utilities/align.hpp"
#include "utilities/exceptions.hpp"
#include "utilities/globalDefinitions.hpp"
#include "utilities/macros.hpp"
#ifdef ZERO
# include "stack_zero.hpp"
#endif
#if INCLUDE_JFR
#include "jfr/support/jfrThreadExtension.hpp"
#endif
class SafeThreadsListPtr;
class ThreadSafepointState;
class ThreadsList;
class ThreadsSMRSupport;
class JvmtiRawMonitor;
class JvmtiThreadState;
class ThreadStatistics;
class ConcurrentLocksDump;
class ParkEvent;
class Parker;
class MonitorInfo;
class ciEnv;
class CompileThread;
class CompileLog;
class CompileTask;
class CompileQueue;
class CompilerCounters;
class vframeArray;
class vframe;
class javaVFrame;
class DeoptResourceMark;
class jvmtiDeferredLocalVariableSet;
class ThreadClosure;
class ICRefillVerifier;
class IdealGraphPrinter;
class JVMCIEnv;
class JVMCIPrimitiveArray;
class Metadata;
class ResourceArea;
DEBUG_ONLY(class ResourceMark;)
class WorkerThread;
// Class hierarchy
// - Thread
// - JavaThread
// - various subclasses eg CompilerThread, ServiceThread
// - NonJavaThread
// - NamedThread
// - VMThread
// - ConcurrentGCThread
// - WorkerThread
// - GangWorker
// - WatcherThread
// - JfrThreadSampler
//
// All Thread subclasses must be either JavaThread or NonJavaThread.
// This means !t->is_Java_thread() iff t is a NonJavaThread, or t is
// a partially constructed/destroyed Thread.
// Thread execution sequence and actions:
// All threads:
// - thread_native_entry // per-OS native entry point
// - stack initialization
// - other OS-level initialization (signal masks etc)
// - handshake with creating thread (if not started suspended)
// - this->call_run() // common shared entry point
// - shared common initialization
// - this->pre_run() // virtual per-thread-type initialization
// - this->run() // virtual per-thread-type "main" logic
// - shared common tear-down
// - this->post_run() // virtual per-thread-type tear-down
// - // 'this' no longer referenceable
// - OS-level tear-down (minimal)
// - final logging
//
// For JavaThread:
// - this->run() // virtual but not normally overridden
// - this->thread_main_inner() // extra call level to ensure correct stack calculations
// - this->entry_point() // set differently for each kind of JavaThread
class Thread: public ThreadShadow {
friend class VMStructs;
friend class JVMCIVMStructs;
private:
#ifndef USE_LIBRARY_BASED_TLS_ONLY
// Current thread is maintained as a thread-local variable
static THREAD_LOCAL Thread* _thr_current;
#endif
// Thread local data area available to the GC. The internal
// structure and contents of this data area is GC-specific.
// Only GC and GC barrier code should access this data area.
GCThreadLocalData _gc_data;
public:
static ByteSize gc_data_offset() {
return byte_offset_of(Thread, _gc_data);
}
template <typename T> T* gc_data() {
STATIC_ASSERT(sizeof(T) <= sizeof(_gc_data));
return reinterpret_cast<T*>(&_gc_data);
}
// 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)
protected:
DEBUG_ONLY(static Thread* _starting_thread;)
// Support for forcing alignment of thread objects for biased locking
void* _real_malloc_address;
// JavaThread lifecycle support:
friend class SafeThreadsListPtr; // for _threads_list_ptr, cmpxchg_threads_hazard_ptr(), {dec_,inc_,}nested_threads_hazard_ptr_cnt(), {g,s}et_threads_hazard_ptr(), inc_nested_handle_cnt(), tag_hazard_ptr() access
friend class ScanHazardPtrGatherProtectedThreadsClosure; // for cmpxchg_threads_hazard_ptr(), get_threads_hazard_ptr(), is_hazard_ptr_tagged() access
friend class ScanHazardPtrGatherThreadsListClosure; // for get_threads_hazard_ptr(), untag_hazard_ptr() access
friend class ScanHazardPtrPrintMatchingThreadsClosure; // for get_threads_hazard_ptr(), is_hazard_ptr_tagged() access
friend class ThreadsSMRSupport; // for _nested_threads_hazard_ptr_cnt, _threads_hazard_ptr, _threads_list_ptr access
ThreadsList* volatile _threads_hazard_ptr;
SafeThreadsListPtr* _threads_list_ptr;
ThreadsList* cmpxchg_threads_hazard_ptr(ThreadsList* exchange_value, ThreadsList* compare_value);
ThreadsList* get_threads_hazard_ptr();
void set_threads_hazard_ptr(ThreadsList* new_list);
static bool is_hazard_ptr_tagged(ThreadsList* list) {
return (intptr_t(list) & intptr_t(1)) == intptr_t(1);
}
static ThreadsList* tag_hazard_ptr(ThreadsList* list) {
return (ThreadsList*)(intptr_t(list) | intptr_t(1));
}
static ThreadsList* untag_hazard_ptr(ThreadsList* list) {
return (ThreadsList*)(intptr_t(list) & ~intptr_t(1));
}
// This field is enabled via -XX:+EnableThreadSMRStatistics:
uint _nested_threads_hazard_ptr_cnt;
void dec_nested_threads_hazard_ptr_cnt() {
assert(_nested_threads_hazard_ptr_cnt != 0, "mismatched {dec,inc}_nested_threads_hazard_ptr_cnt()");
_nested_threads_hazard_ptr_cnt--;
}
void inc_nested_threads_hazard_ptr_cnt() {
_nested_threads_hazard_ptr_cnt++;
}
uint nested_threads_hazard_ptr_cnt() {
return _nested_threads_hazard_ptr_cnt;
}
public:
void* operator new(size_t size) throw() { return allocate(size, true); }
void* operator new(size_t size, const std::nothrow_t& nothrow_constant) throw() {
return allocate(size, false); }
void operator delete(void* p);
protected:
static void* allocate(size_t size, bool throw_excpt, MEMFLAGS flags = mtThread);
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
_has_async_exception = 0x00000001U, // there is a pending async exception
_critical_native_unlock = 0x00000002U, // Must call back to unlock JNI critical lock
_trace_flag = 0x00000004U // call tracing backend
};
// 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;
DEBUG_ONLY(bool _suspendible_thread;)
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; }
// Determines if a heap allocation failure will be retried
// (e.g., by deoptimizing and re-executing in the interpreter).
// In this case, the failed allocation must raise
// Universe::out_of_memory_error_retry() and omit side effects
// such as JVMTI events and handling -XX:+HeapDumpOnOutOfMemoryError
// and -XX:OnOutOfMemoryError.
virtual bool in_retryable_allocation() const { return false; }
#ifdef ASSERT
void set_suspendible_thread() {
_suspendible_thread = true;
}
void clear_suspendible_thread() {
_suspendible_thread = false;
}
bool is_suspendible_thread() { return _suspendible_thread; }
#endif
private:
// 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;
// Claim value for parallel iteration over threads.
uintx _threads_do_token;
// Support for GlobalCounter
private:
volatile uintx _rcu_counter;
public:
volatile uintx* get_rcu_counter() {
return &_rcu_counter;
}
public:
void set_last_handle_mark(HandleMark* mark) { _last_handle_mark = mark; }
HandleMark* last_handle_mark() const { return _last_handle_mark; }
private:
#ifdef ASSERT
ICRefillVerifier* _missed_ic_stub_refill_verifier;
public:
ICRefillVerifier* missed_ic_stub_refill_verifier() {
return _missed_ic_stub_refill_verifier;
}
void set_missed_ic_stub_refill_verifier(ICRefillVerifier* verifier) {
_missed_ic_stub_refill_verifier = verifier;
}
#endif // ASSERT
private:
// Debug support for checking if code allows safepoints or not.
// Safepoints 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 _no_safepoint_count is non-zero, then an assertion failure will happen in any of
// the above cases.
//
// The class NoSafepointVerifier is used to set this counter.
//
NOT_PRODUCT(int _no_safepoint_count;) // If 0, thread allow a safepoint to happen
private:
// Used by SkipGCALot class.
NOT_PRODUCT(bool _skip_gcalot;) // Should we elide gc-a-lot?
friend class GCLocker;
friend class NoSafepointVerifier;
friend class PauseNoSafepointVerifier;
volatile void* _polling_page; // Thread local polling page
ThreadLocalAllocBuffer _tlab; // Thread-local eden
jlong _allocated_bytes; // Cumulative number of bytes allocated on
// the Java heap
ThreadHeapSampler _heap_sampler; // For use when sampling the memory.
ThreadStatisticalInfo _statistical_info; // Statistics about the thread
JFR_ONLY(DEFINE_THREAD_LOCAL_FIELD_JFR;) // Thread-local data for jfr
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
JvmtiRawMonitor* _current_pending_raw_monitor; // JvmtiRawMonitor this thread
// is waiting to lock
// ObjectMonitor on which this thread called Object.wait()
ObjectMonitor* _current_waiting_monitor;
// Per-thread ObjectMonitor lists:
public:
ObjectMonitor* om_free_list; // SLL of free ObjectMonitors
int om_free_count; // # on om_free_list
int om_free_provision; // # to try to allocate next
ObjectMonitor* om_in_use_list; // SLL of in-use ObjectMonitors
int om_in_use_count; // # on om_in_use_list
#ifdef ASSERT
private:
volatile uint64_t _visited_for_critical_count;
public:
void set_visited_for_critical_count(uint64_t safepoint_id) {
assert(_visited_for_critical_count == 0, "Must be reset before set");
assert((safepoint_id & 0x1) == 1, "Must be odd");
_visited_for_critical_count = safepoint_id;
}
void reset_visited_for_critical_count(uint64_t safepoint_id) {
assert(_visited_for_critical_count == safepoint_id, "Was not visited");
_visited_for_critical_count = 0;
}
bool was_visited_for_critical_count(uint64_t safepoint_id) const {
return _visited_for_critical_count == safepoint_id;
}
#endif
public:
enum {
is_definitely_current_thread = true
};
// Constructor
Thread();
virtual ~Thread() = 0; // Thread is abstract.
// Manage Thread::current()
void initialize_thread_current();
static void clear_thread_current(); // TLS cleanup needed before threads terminate
protected:
// To be implemented by children.
virtual void run() = 0;
virtual void pre_run() = 0;
virtual void post_run() = 0; // Note: Thread must not be deleted prior to calling this!
#ifdef ASSERT
enum RunState {
PRE_CALL_RUN,
CALL_RUN,
PRE_RUN,
RUN,
POST_RUN
// POST_CALL_RUN - can't define this one as 'this' may be deleted when we want to set it
};
RunState _run_state; // for lifecycle checks
#endif
public:
// invokes <ChildThreadClass>::run(), with common preparations and cleanups.
void call_run();
// Testers
virtual bool is_VM_thread() const { return false; }
virtual bool is_Java_thread() const { return false; }
virtual bool is_Compiler_thread() const { return false; }
virtual bool is_Code_cache_sweeper_thread() const { return false; }
virtual bool is_service_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 bool is_Named_thread() const { return false; }
virtual bool is_Worker_thread() const { return false; }
// Can this thread make Java upcalls
virtual bool can_call_java() const { return false; }
// Is this a JavaThread that is on the VM's current ThreadsList?
// If so it must participate in the safepoint protocol.
virtual bool is_active_Java_thread() const { return false; }
// Casts
virtual WorkerThread* as_Worker_thread() const { return NULL; }
virtual char* name() const { return (char*)"Unknown thread"; }
// Returns the current thread (ASSERTS if NULL)
static inline Thread* current();
// Returns the current thread, or NULL if not attached
static inline Thread* current_or_null();
// Returns the current thread, or NULL if not attached, and is
// safe for use from signal-handlers
static inline Thread* current_or_null_safe();
// Common thread operations
#ifdef ASSERT
static void check_for_dangling_thread_pointer(Thread *thread);
#endif
static void set_priority(Thread* thread, ThreadPriority priority);
static ThreadPriority get_priority(const Thread* const thread);
static void start(Thread* thread);
void set_native_thread_name(const char *name) {
assert(Thread::current() == this, "set_native_thread_name can only be called on the current thread");
os::set_native_thread_name(name);
}
ObjectMonitor** om_in_use_list_addr() { return (ObjectMonitor **)&om_in_use_list; }
Monitor* SR_lock() const { return _SR_lock; }
bool has_async_exception() const { return (_suspend_flags & _has_async_exception) != 0; }
inline void set_suspend_flag(SuspendFlags f);
inline void clear_suspend_flag(SuspendFlags f);
inline void set_has_async_exception();
inline void clear_has_async_exception();
bool do_critical_native_unlock() const { return (_suspend_flags & _critical_native_unlock) != 0; }
inline void set_critical_native_unlock();
inline void clear_critical_native_unlock();
inline void set_trace_flag();
inline void clear_trace_flag();
// Support for Unhandled Oop detection
// Add the field for both, fastdebug and debug, builds to keep
// Thread's fields layout the same.
// Note: CHECK_UNHANDLED_OOPS is defined only for fastdebug build.
#ifdef CHECK_UNHANDLED_OOPS
private:
UnhandledOops* _unhandled_oops;
#elif defined(ASSERT)
private:
void* _unhandled_oops;
#endif
#ifdef CHECK_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();
}
#endif // CHECK_UNHANDLED_OOPS
public:
#ifndef PRODUCT
bool skip_gcalot() { return _skip_gcalot; }
void set_skip_gcalot(bool v) { _skip_gcalot = v; }
#endif
// 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; }
GrowableArray<Metadata*>* metadata_handles() const { return _metadata_handles; }
void set_metadata_handles(GrowableArray<Metadata*>* handles){ _metadata_handles = handles; }
// Thread-Local Allocation Buffer (TLAB) support
ThreadLocalAllocBuffer& tlab() { return _tlab; }
void initialize_tlab() {
if (UseTLAB) {
tlab().initialize();
}
}
jlong allocated_bytes() { return _allocated_bytes; }
void set_allocated_bytes(jlong value) { _allocated_bytes = value; }
void incr_allocated_bytes(jlong size) { _allocated_bytes += size; }
inline jlong cooked_allocated_bytes();
ThreadHeapSampler& heap_sampler() { return _heap_sampler; }
ThreadStatisticalInfo& statistical_info() { return _statistical_info; }
JFR_ONLY(DEFINE_THREAD_LOCAL_ACCESSOR_JFR;)
bool is_trace_suspend() { return (_suspend_flags & _trace_flag) != 0; }
// 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;
}
// For tracking the Jvmti raw monitor the thread is pending on.
JvmtiRawMonitor* current_pending_raw_monitor() {
return _current_pending_raw_monitor;
}
void set_current_pending_raw_monitor(JvmtiRawMonitor* monitor) {
_current_pending_raw_monitor = monitor;
}
// GC support
// Apply "f->do_oop" to all root oops in "this".
// Used by JavaThread::oops_do.
// Apply "cf->do_code_blob" (if !NULL) to all code blobs active in frames
virtual void oops_do(OopClosure* f, CodeBlobClosure* cf);
// Handles the parallel case for claim_threads_do.
private:
bool claim_par_threads_do(uintx claim_token);
public:
// Requires that "claim_token" is that of the current iteration.
// If "is_par" is false, sets the token of "this" to
// "claim_token", and returns "true". If "is_par" is true,
// uses an atomic instruction to set the current thread's token to
// "claim_token", if it is not already. Returns "true" iff the
// calling thread does the update, this indicates that the calling thread
// has claimed the thread in the current iteration.
bool claim_threads_do(bool is_par, uintx claim_token) {
if (!is_par) {
_threads_do_token = claim_token;
return true;
} else {
return claim_par_threads_do(claim_token);
}
}
uintx threads_do_token() const { return _threads_do_token; }
// jvmtiRedefineClasses support
void metadata_handles_do(void f(Metadata*));
// Used by fast lock support
virtual bool is_lock_owned(address adr) const;
// Check if address is in the stack of the thread (not just for locks).
// Warning: the method can only be used on the running thread
bool is_in_stack(address adr) const;
// Check if address is in the usable part of the stack (excludes protected
// guard pages)
bool is_in_usable_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;
DEBUG_ONLY(ResourceMark* _current_resource_mark;)
// Thread local handle area for allocation of handles within the VM
HandleArea* _handle_area;
GrowableArray<Metadata*>* _metadata_handles;
// Support for stack overflow handling, get_thread, etc.
address _stack_base;
size_t _stack_size;
int _lgrp_id;
volatile void** polling_page_addr() { return &_polling_page; }
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; }
address stack_end() const { return stack_base() - stack_size(); }
void record_stack_base_and_size();
void register_thread_stack_with_NMT() NOT_NMT_RETURN;
bool on_local_stack(address adr) const {
// QQQ this has knowledge of direction, ought to be a stack method
return (_stack_base > adr && adr >= stack_end());
}
int lgrp_id() const { return _lgrp_id; }
void set_lgrp_id(int value) { _lgrp_id = value; }
// Printing
void print_on(outputStream* st, bool print_extended_info) const;
virtual void print_on(outputStream* st) const { print_on(st, false); }
void print() const;
virtual void print_on_error(outputStream* st, char* buf, int buflen) const;
void print_value_on(outputStream* st) const;
// Debug-only code
#ifdef ASSERT
private:
// Deadlock detection support for Mutex locks. List of locks own by thread.
Mutex* _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); }
Mutex* owned_locks() const { return _owned_locks; }
bool owns_locks() const { return owned_locks() != NULL; }
// Deadlock detection
ResourceMark* current_resource_mark() { return _current_resource_mark; }
void set_current_resource_mark(ResourceMark* rm) { _current_resource_mark = rm; }
#endif // ASSERT
// These functions check conditions on a JavaThread before possibly going to a safepoint,
// including NoSafepointVerifier.
void check_for_valid_safepoint_state() NOT_DEBUG_RETURN;
void check_possible_safepoint() NOT_DEBUG_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 polling_page_offset() { return byte_offset_of(Thread, _polling_page); }
static ByteSize tlab_start_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::start_offset(); }
static ByteSize tlab_end_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::end_offset(); }
static ByteSize tlab_top_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::top_offset(); }
static ByteSize tlab_pf_top_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::pf_top_offset(); }
static ByteSize allocated_bytes_offset() { return byte_offset_of(Thread, _allocated_bytes); }
JFR_ONLY(DEFINE_THREAD_LOCAL_OFFSET_JFR;)
public:
volatile intptr_t _Stalled;
volatile int _TypeTag;
ParkEvent * _ParkEvent; // for Object monitors and JVMTI raw monitors
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;
// 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 muxRelease(volatile intptr_t * Lock);
};
// Inline implementation of Thread::current()
inline Thread* Thread::current() {
Thread* current = current_or_null();
assert(current != NULL, "Thread::current() called on detached thread");
return current;
}
inline Thread* Thread::current_or_null() {
#ifndef USE_LIBRARY_BASED_TLS_ONLY
return _thr_current;
#else
if (ThreadLocalStorage::is_initialized()) {
return ThreadLocalStorage::thread();
}
return NULL;
#endif
}
inline Thread* Thread::current_or_null_safe() {
if (ThreadLocalStorage::is_initialized()) {
return ThreadLocalStorage::thread();
}
return NULL;
}
class NonJavaThread: public Thread {
friend class VMStructs;
NonJavaThread* volatile _next;
class List;
static List _the_list;
void add_to_the_list();
void remove_from_the_list();
protected:
virtual void pre_run();
virtual void post_run();
public:
NonJavaThread();
~NonJavaThread();
class Iterator;
};
// Provides iteration over the list of NonJavaThreads.
// List addition occurs in pre_run(), and removal occurs in post_run(),
// so that only live fully-initialized threads can be found in the list.
// Threads created after an iterator is constructed will not be visited
// by the iterator. The scope of an iterator is a critical section; there
// must be no safepoint checks in that scope.
class NonJavaThread::Iterator : public StackObj {
uint _protect_enter;
NonJavaThread* _current;
NONCOPYABLE(Iterator);
public:
Iterator();
~Iterator();
bool end() const { return _current == NULL; }
NonJavaThread* current() const { return _current; }
void step();
};
// Name support for threads. non-JavaThread subclasses with multiple
// uniquely named instances should derive from this.
class NamedThread: public NonJavaThread {
friend class VMStructs;
enum {
max_name_len = 64
};
private:
char* _name;
// log JavaThread being processed by oops_do
JavaThread* _processed_thread;
uint _gc_id; // The current GC id when a thread takes part in GC
public:
NamedThread();
~NamedThread();
// May only be called once per thread.
void set_name(const char* format, ...) ATTRIBUTE_PRINTF(2, 3);
virtual bool is_Named_thread() const { return true; }
virtual char* name() const { return _name == NULL ? (char*)"Unknown Thread" : _name; }
JavaThread *processed_thread() { return _processed_thread; }
void set_processed_thread(JavaThread *thread) { _processed_thread = thread; }
virtual void print_on(outputStream* st) const;
void set_gc_id(uint gc_id) { _gc_id = gc_id; }
uint gc_id() { return _gc_id; }
};
// Worker threads are named and have an id of an assigned work.
class WorkerThread: public NamedThread {
private:
uint _id;
public:
WorkerThread() : _id(0) { }
virtual bool is_Worker_thread() const { return true; }
virtual WorkerThread* as_Worker_thread() const {
assert(is_Worker_thread(), "Dubious cast to WorkerThread*?");
return (WorkerThread*) this;
}
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 NonJavaThread {
friend class VMStructs;
protected:
virtual void run();
private:
static WatcherThread* _watcher_thread;
static bool _startable;
// volatile due to at least one lock-free read
volatile static bool _should_terminate;
public:
enum SomeConstants {
delay_interval = 10 // interrupt delay in milliseconds
};
// Constructor
WatcherThread();
// No destruction allowed
~WatcherThread() {
guarantee(false, "WatcherThread deletion must fix the race with VM termination");
}
// 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 unpark();
// 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();
// Only allow start once the VM is sufficiently initialized
// Otherwise the first task to enroll will trigger the start
static void make_startable();
private:
int sleep() const;
};
class CompilerThread;
typedef void (*ThreadFunction)(JavaThread*, TRAPS);
class JavaThread: public Thread {
friend class VMStructs;
friend class JVMCIVMStructs;
friend class WhiteBox;
private:
bool _on_thread_list; // Is set when this JavaThread is added to 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
CompiledMethod* _deopt_nmethod; // CompiledMethod that is currently being deoptimized
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 Method*. 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.
Method* _callee_target;
// Used to pass back results to the interpreter or generated code running Java code.
oop _vm_result; // oop result is GC-preserved
Metadata* _vm_result_2; // non-oop result
// See ReduceInitialCardMarks: this holds the precise space interval of
// the most recent slow path allocation for which compiled code has
// elided card-marks for performance along the fast-path.
MemRegion _deferred_card_mark;
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.
volatile 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.
// JNI attach states:
enum JNIAttachStates {
_not_attaching_via_jni = 1, // thread is not attaching via JNI
_attaching_via_jni, // thread is attaching via JNI
_attached_via_jni // thread has attached via JNI
};
// A regular JavaThread's _jni_attach_state is _not_attaching_via_jni.
// A native thread that is attaching via JNI starts with a value
// of _attaching_via_jni and transitions to _attached_via_jni.
volatile JNIAttachStates _jni_attach_state;
public:
// State of the stack guard pages for this thread.
enum StackGuardState {
stack_guard_unused, // not needed
stack_guard_reserved_disabled,
stack_guard_yellow_reserved_disabled,// disabled (temporarily) after stack overflow
stack_guard_enabled // enabled
};
private:
#if INCLUDE_JVMCI
// The _pending_* fields below are used to communicate extra information
// from an uncommon trap in JVMCI compiled code to the uncommon trap handler.
// Communicates the DeoptReason and DeoptAction of the uncommon trap
int _pending_deoptimization;
// Specifies whether the uncommon trap is to bci 0 of a synchronized method
// before the monitor has been acquired.
bool _pending_monitorenter;
// Specifies if the DeoptReason for the last uncommon trap was Reason_transfer_to_interpreter
bool _pending_transfer_to_interpreter;
// True if in a runtime call from compiled code that will deoptimize
// and re-execute a failed heap allocation in the interpreter.
bool _in_retryable_allocation;
// An id of a speculation that JVMCI compiled code can use to further describe and
// uniquely identify the speculative optimization guarded by the uncommon trap
jlong _pending_failed_speculation;
// These fields are mutually exclusive in terms of live ranges.
union {
// Communicates the pc at which the most recent implicit exception occurred
// from the signal handler to a deoptimization stub.
address _implicit_exception_pc;
// Communicates an alternative call target to an i2c stub from a JavaCall .
address _alternate_call_target;
} _jvmci;
// Support for high precision, thread sensitive counters in JVMCI compiled code.
jlong* _jvmci_counters;
public:
static jlong* _jvmci_old_thread_counters;
static void collect_counters(jlong* array, int length);
void resize_counters(int current_size, int new_size);
static void resize_all_jvmci_counters(int new_size);
private:
#endif // INCLUDE_JVMCI
StackGuardState _stack_guard_state;
// Precompute the limit of the stack as used in stack overflow checks.
// We load it from here to simplify the stack overflow check in assembly.
address _stack_overflow_limit;
address _reserved_stack_activation;
// 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 _is_method_handle_return; // true (== 1) if the current exception PC is a MethodHandle call site.
private:
// support for JNI critical regions
jint _jni_active_critical; // count of entries into JNI critical region
// Checked JNI: function name requires exception check
char* _pending_jni_exception_check_fn;
// 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;
// If reallocation of scalar replaced objects fails, we throw OOM
// and during exception propagation, pop the top
// _frames_to_pop_failed_realloc frames, the ones that reference
// failed reallocations.
int _frames_to_pop_failed_realloc;
friend class VMThread;
friend class ThreadWaitTransition;
friend class VM_Exit;
void initialize(); // Initialized the instance variables
public:
// Constructor
JavaThread(bool is_attaching_via_jni = 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 // ASSERT
//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;
}
// This function is called at thread creation to allow
// platform specific thread variables to be initialized.
void cache_global_variables();
// 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(bool is_daemon);
// Testers
virtual bool is_Java_thread() const { return true; }
virtual bool can_call_java() const { return true; }
virtual bool is_active_Java_thread() const {
return on_thread_list() && !is_terminated();
}
// 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; }
// 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, const 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
inline JavaThreadState thread_state() const;
inline void set_thread_state(JavaThreadState s);
inline void set_thread_state_fence(JavaThreadState s); // fence after setting thread state
inline ThreadSafepointState* safepoint_state() const;
inline void set_safepoint_state(ThreadSafepointState* state);
inline bool is_at_poll_safepoint();
// JavaThread termination and lifecycle support:
void smr_delete();
bool on_thread_list() const { return _on_thread_list; }
void set_on_thread_list() { _on_thread_list = true; }
// thread has called JavaThread::exit() or is terminated
bool is_exiting() const;
// 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 check_is_terminated(TerminatedTypes l_terminated) const {
return l_terminated != _not_terminated && l_terminated != _thread_exiting;
}
bool is_terminated() const;
void set_terminated(TerminatedTypes t);
// special for Threads::remove() which is static:
void set_terminated_value();
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; }
inline void set_polling_page_release(void* poll_value);
inline void set_polling_page(void* poll_value);
inline volatile void* get_polling_page();
private:
// Support for thread handshake operations
HandshakeState _handshake;
public:
void set_handshake_operation(HandshakeOperation* op) {
_handshake.set_operation(this, op);
}
bool has_handshake() const {
return _handshake.has_operation();
}
void handshake_process_by_self() {
_handshake.process_by_self(this);
}
bool handshake_try_process_by_vmThread() {
return _handshake.try_process_by_vmThread(this);
}
// Suspend/resume support for JavaThread
private:
inline void set_ext_suspended();
inline void clear_ext_suspended();
public:
void java_suspend(); // higher-level suspension logic called by the public APIs
void java_resume(); // higher-level resume logic called by the public APIs
int java_suspend_self(); // low-level self-suspension mechanics
private:
// mid-level wrapper around java_suspend_self to set up correct state and
// check for a pending safepoint at the end
void java_suspend_self_with_safepoint_check();
public:
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);
// Same as check_special_condition_for_native_trans but finishes the
// transition into thread_in_Java mode so that it can potentially
// block.
static void check_special_condition_for_native_trans_and_transition(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) {
MutexLocker 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);
// test for suspend - most (all?) of these should go away
bool is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits);
inline void set_external_suspend();
inline void clear_external_suspend();
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 JFR_ONLY(| _trace_flag))) != 0;
}
// external suspend request is completed
bool is_ext_suspended() const {
return (_suspend_flags & _ext_suspended) != 0;
}
bool is_external_suspend_with_lock() const {
MutexLocker 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");
MutexLocker 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;
}
// utility methods to see if we are doing some kind of suspension
bool is_being_ext_suspended() const {
MutexLocker 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() {
// 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_trace_suspend();
}
void set_pending_unsafe_access_error() { _special_runtime_exit_condition = _async_unsafe_access_error; }
inline void set_pending_async_exception(oop e);
// 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 deferring 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; }
void set_deopt_compiled_method(CompiledMethod* nm) { _deopt_nmethod = nm; }
CompiledMethod* deopt_compiled_method() { return _deopt_nmethod; }
Method* callee_target() const { return _callee_target; }
void set_callee_target (Method* 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; }
Metadata* vm_result_2() const { return _vm_result_2; }
void set_vm_result_2 (Metadata* x) { _vm_result_2 = x; }
MemRegion deferred_card_mark() const { return _deferred_card_mark; }
void set_deferred_card_mark(MemRegion mr) { _deferred_card_mark = mr; }
#if INCLUDE_JVMCI
int pending_deoptimization() const { return _pending_deoptimization; }
jlong pending_failed_speculation() const { return _pending_failed_speculation; }
bool has_pending_monitorenter() const { return _pending_monitorenter; }
void set_pending_monitorenter(bool b) { _pending_monitorenter = b; }
void set_pending_deoptimization(int reason) { _pending_deoptimization = reason; }
void set_pending_failed_speculation(jlong failed_speculation) { _pending_failed_speculation = failed_speculation; }
void set_pending_transfer_to_interpreter(bool b) { _pending_transfer_to_interpreter = b; }
void set_jvmci_alternate_call_target(address a) { assert(_jvmci._alternate_call_target == NULL, "must be"); _jvmci._alternate_call_target = a; }
void set_jvmci_implicit_exception_pc(address a) { assert(_jvmci._implicit_exception_pc == NULL, "must be"); _jvmci._implicit_exception_pc = a; }
virtual bool in_retryable_allocation() const { return _in_retryable_allocation; }
void set_in_retryable_allocation(bool b) { _in_retryable_allocation = b; }
#endif // INCLUDE_JVMCI
// Exception handling for compiled methods
oop exception_oop() const { return _exception_oop; }
address exception_pc() const { return _exception_pc; }
address exception_handler_pc() const { return _exception_handler_pc; }
bool is_method_handle_return() const { return _is_method_handle_return == 1; }
void set_exception_oop(oop o) { (void)const_cast<oop&>(_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_is_method_handle_return(bool value) { _is_method_handle_return = value ? 1 : 0; }
void clear_exception_oop_and_pc() {
set_exception_oop(NULL);
set_exception_pc(NULL);
}
// Stack overflow support
//
// (small addresses)
//
// -- <-- stack_end() ---
// | |
// | red pages |
// | |
// -- <-- stack_red_zone_base() |
// | |
// | guard
// | yellow pages zone
// | |
// | |
// -- <-- stack_yellow_zone_base() |
// | |
// | |
// | reserved pages |
// | |
// -- <-- stack_reserved_zone_base() --- ---
// /|\ shadow <-- stack_overflow_limit() (somewhere in here)
// | zone
// \|/ size
// some untouched memory ---
//
//
// --
// |
// | shadow zone
// |
// --
// x frame n
// --
// x frame n-1
// x
// --
// ...
//
// --
// x frame 0
// -- <-- stack_base()
//
// (large addresses)
//
private:
// These values are derived from flags StackRedPages, StackYellowPages,
// StackReservedPages and StackShadowPages. The zone size is determined
// ergonomically if page_size > 4K.
static size_t _stack_red_zone_size;
static size_t _stack_yellow_zone_size;
static size_t _stack_reserved_zone_size;
static size_t _stack_shadow_zone_size;
public:
inline size_t stack_available(address cur_sp);
static size_t stack_red_zone_size() {
assert(_stack_red_zone_size > 0, "Don't call this before the field is initialized.");
return _stack_red_zone_size;
}
static void set_stack_red_zone_size(size_t s) {
assert(is_aligned(s, os::vm_page_size()),
"We can not protect if the red zone size is not page aligned.");
assert(_stack_red_zone_size == 0, "This should be called only once.");
_stack_red_zone_size = s;
}
address stack_red_zone_base() {
return (address)(stack_end() + stack_red_zone_size());
}
bool in_stack_red_zone(address a) {
return a <= stack_red_zone_base() && a >= stack_end();
}
static size_t stack_yellow_zone_size() {
assert(_stack_yellow_zone_size > 0, "Don't call this before the field is initialized.");
return _stack_yellow_zone_size;
}
static void set_stack_yellow_zone_size(size_t s) {
assert(is_aligned(s, os::vm_page_size()),
"We can not protect if the yellow zone size is not page aligned.");
assert(_stack_yellow_zone_size == 0, "This should be called only once.");
_stack_yellow_zone_size = s;
}
static size_t stack_reserved_zone_size() {
// _stack_reserved_zone_size may be 0. This indicates the feature is off.
return _stack_reserved_zone_size;
}
static void set_stack_reserved_zone_size(size_t s) {
assert(is_aligned(s, os::vm_page_size()),
"We can not protect if the reserved zone size is not page aligned.");
assert(_stack_reserved_zone_size == 0, "This should be called only once.");
_stack_reserved_zone_size = s;
}
address stack_reserved_zone_base() {
return (address)(stack_end() +
(stack_red_zone_size() + stack_yellow_zone_size() + stack_reserved_zone_size()));
}
bool in_stack_reserved_zone(address a) {
return (a <= stack_reserved_zone_base()) &&
(a >= (address)((intptr_t)stack_reserved_zone_base() - stack_reserved_zone_size()));
}
static size_t stack_yellow_reserved_zone_size() {
return _stack_yellow_zone_size + _stack_reserved_zone_size;
}
bool in_stack_yellow_reserved_zone(address a) {
return (a <= stack_reserved_zone_base()) && (a >= stack_red_zone_base());
}
// Size of red + yellow + reserved zones.
static size_t stack_guard_zone_size() {
return stack_red_zone_size() + stack_yellow_reserved_zone_size();
}
static size_t stack_shadow_zone_size() {
assert(_stack_shadow_zone_size > 0, "Don't call this before the field is initialized.");
return _stack_shadow_zone_size;
}
static void set_stack_shadow_zone_size(size_t s) {
// The shadow area is not allocated or protected, so
// it needs not be page aligned.
// But the stack bang currently assumes that it is a
// multiple of page size. This guarantees that the bang
// loop touches all pages in the shadow zone.
// This can be guaranteed differently, as well. E.g., if
// the page size is a multiple of 4K, banging in 4K steps
// suffices to touch all pages. (Some pages are banged
// several times, though.)
assert(is_aligned(s, os::vm_page_size()),
"Stack bang assumes multiple of page size.");
assert(_stack_shadow_zone_size == 0, "This should be called only once.");
_stack_shadow_zone_size = s;
}
void create_stack_guard_pages();
void remove_stack_guard_pages();
void enable_stack_reserved_zone();
void disable_stack_reserved_zone();
void enable_stack_yellow_reserved_zone();
void disable_stack_yellow_reserved_zone();
void enable_stack_red_zone();
void disable_stack_red_zone();
inline bool stack_guard_zone_unused();
inline bool stack_yellow_reserved_zone_disabled();
inline bool stack_reserved_zone_disabled();
inline bool stack_guards_enabled();
address reserved_stack_activation() const { return _reserved_stack_activation; }
void set_reserved_stack_activation(address addr) {
assert(_reserved_stack_activation == stack_base()
|| _reserved_stack_activation == NULL
|| addr == stack_base(), "Must not be set twice");
_reserved_stack_activation = addr;
}
// 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);
address stack_overflow_limit() { return _stack_overflow_limit; }
void set_stack_overflow_limit() {
_stack_overflow_limit =
stack_end() + MAX2(JavaThread::stack_guard_zone_size(), JavaThread::stack_shadow_zone_size());
}
// 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; }
// For assembly stub generation
static ByteSize threadObj_offset() { return byte_offset_of(JavaThread, _threadObj); }
static ByteSize jni_environment_offset() { return byte_offset_of(JavaThread, _jni_environment); }
static ByteSize pending_jni_exception_check_fn_offset() {
return byte_offset_of(JavaThread, _pending_jni_exception_check_fn);
}
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); }
#if INCLUDE_JVMCI
static ByteSize pending_deoptimization_offset() { return byte_offset_of(JavaThread, _pending_deoptimization); }
static ByteSize pending_monitorenter_offset() { return byte_offset_of(JavaThread, _pending_monitorenter); }
static ByteSize pending_failed_speculation_offset() { return byte_offset_of(JavaThread, _pending_failed_speculation); }
static ByteSize jvmci_alternate_call_target_offset() { return byte_offset_of(JavaThread, _jvmci._alternate_call_target); }
static ByteSize jvmci_implicit_exception_pc_offset() { return byte_offset_of(JavaThread, _jvmci._implicit_exception_pc); }
static ByteSize jvmci_counters_offset() { return byte_offset_of(JavaThread, _jvmci_counters); }
#endif // INCLUDE_JVMCI
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 stack_overflow_limit_offset() { return byte_offset_of(JavaThread, _stack_overflow_limit); }
static ByteSize is_method_handle_return_offset() { return byte_offset_of(JavaThread, _is_method_handle_return); }
static ByteSize stack_guard_state_offset() { return byte_offset_of(JavaThread, _stack_guard_state); }
static ByteSize reserved_stack_activation_offset() { return byte_offset_of(JavaThread, _reserved_stack_activation); }
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); }
static ByteSize should_post_on_exceptions_flag_offset() {
return byte_offset_of(JavaThread, _should_post_on_exceptions_flag);
}
static ByteSize doing_unsafe_access_offset() { return byte_offset_of(JavaThread, _doing_unsafe_access); }
// 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; }
bool in_last_critical() { return _jni_active_critical == 1; }
inline void enter_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?");
}
// Checked JNI: is the programmer required to check for exceptions, if so specify
// which function name. Returning to a Java frame should implicitly clear the
// pending check, this is done for Native->Java transitions (i.e. user JNI code).
// VM->Java transistions are not cleared, it is expected that JNI code enclosed
// within ThreadToNativeFromVM makes proper exception checks (i.e. VM internal).
bool is_pending_jni_exception_check() const { return _pending_jni_exception_check_fn != NULL; }
void clear_pending_jni_exception_check() { _pending_jni_exception_check_fn = NULL; }
const char* get_pending_jni_exception_check() const { return _pending_jni_exception_check_fn; }
void set_pending_jni_exception_check(const char* fn_name) { _pending_jni_exception_check_fn = (char*) fn_name; }
// 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, CodeBlobClosure* cf);
// Sweeper operations
virtual void nmethods_do(CodeBlobClosure* cf);
// RedefineClasses Support
void metadata_do(MetadataClosure* f);
// Debug method asserting thread states are correct during a handshake operation.
DEBUG_ONLY(void verify_states_for_handshake();)
// Misc. operations
char* name() const { return (char*)get_thread_name(); }
void print_on(outputStream* st, bool print_extended_info) const;
void print_on(outputStream* st) const { print_on(st, false); }
void print() const;
void print_thread_state_on(outputStream*) const PRODUCT_RETURN;
void print_on_error(outputStream* st, char* buf, int buflen) const;
void print_name_on_error(outputStream* st, char* buf, int buflen) const;
void verify();
const char* get_thread_name() const;
protected:
// factor out low-level mechanics for use in both normal and error cases
virtual const char* get_thread_name_string(char* buf = NULL, int buflen = 0) const;
public:
// 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
Klass* 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;
// Print an annotated view of the stack frames
void print_frame_layout(int depth = 0, bool validate_only = false) NOT_DEBUG_RETURN;
void validate_frame_layout() {
print_frame_layout(0, true);
}
// Function for testing deoptimization
void deoptimize();
void make_zombies();
void deoptimize_marked_methods();
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();
protected:
virtual void pre_run();
virtual void run();
void thread_main_inner();
virtual void post_run();
private:
GrowableArray<oop>* _array_for_gc;
public:
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; }
// A JvmtiThreadState is lazily allocated. This jvmti_thread_state()
// getter is used to get this JavaThread's JvmtiThreadState if it has
// one which means NULL can be returned. JvmtiThreadState::state_for()
// is used to get the specified JavaThread's JvmtiThreadState if it has
// one or it allocates a new JvmtiThreadState for the JavaThread and
// returns it. JvmtiThreadState::state_for() will return NULL only if
// the specified JavaThread is exiting.
JvmtiThreadState *jvmti_thread_state() const { return _jvmti_thread_state; }
static ByteSize jvmti_thread_state_offset() { return byte_offset_of(JavaThread, _jvmti_thread_state); }
// 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
int frames_to_pop_failed_realloc() const { return _frames_to_pop_failed_realloc; }
void set_frames_to_pop_failed_realloc(int nb) { _frames_to_pop_failed_realloc = nb; }
void dec_frames_to_pop_failed_realloc() { _frames_to_pop_failed_realloc--; }
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;
// 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; }
// support for cached flag that indicates whether exceptions need to be posted for this thread
// if this is false, we can avoid deoptimizing when events are thrown
// this gets set to reflect whether jvmtiExport::post_exception_throw would actually do anything
private:
int _should_post_on_exceptions_flag;
public:
int should_post_on_exceptions_flag() { return _should_post_on_exceptions_flag; }
void set_should_post_on_exceptions_flag(int val) { _should_post_on_exceptions_flag = val; }
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 OS_CPU_HEADER(thread)
// 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_via_jni() const { return _jni_attach_state == _attaching_via_jni; }
bool has_attached_via_jni() const { return is_attaching_via_jni() || _jni_attach_state == _attached_via_jni; }
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