void BiasedLocking::preserve_marks() {
if (!UseBiasedLocking)
return;
assert(SafepointSynchronize::is_at_safepoint(), "must only be called while at safepoint");
assert(_preserved_oop_stack == NULL, "double initialization");
assert(_preserved_mark_stack == NULL, "double initialization");
// In order to reduce the number of mark words preserved during GC
// due to the presence of biased locking, we reinitialize most mark
// words to the class's prototype during GC -- even those which have
// a currently valid bias owner. One important situation where we
// must not clobber a bias is when a biased object is currently
// locked. To handle this case we iterate over the currently-locked
// monitors in a prepass and, if they are biased, preserve their
// mark words here. This should be a relatively small set of objects
// especially compared to the number of objects in the heap.
_preserved_mark_stack = new (ResourceObj::C_HEAP) GrowableArray<markOop>(10, true);
_preserved_oop_stack = new (ResourceObj::C_HEAP) GrowableArray<Handle>(10, true);
ResourceMark rm;
Thread* cur = Thread::current();
for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
if (thread->has_last_Java_frame()) {
RegisterMap rm(thread);
for (javaVFrame* vf = thread->last_java_vframe(&rm); vf != NULL; vf = vf->java_sender()) {
GrowableArray<MonitorInfo*> *monitors = vf->monitors();
if (monitors != NULL) {
int len = monitors->length();
// Walk monitors youngest to oldest
for (int i = len - 1; i >= 0; i--) {
MonitorInfo* mon_info = monitors->at(i);
oop owner = mon_info->owner();
if (owner != NULL) {
markOop mark = owner->mark();
if (mark->has_bias_pattern()) {
_preserved_oop_stack->push(Handle(cur, owner));
_preserved_mark_stack->push(mark);
}
}
}
}
}
}
}
}
void ZeroStack::handle_overflow(TRAPS) {
JavaThread *thread = (JavaThread *) THREAD;
// Set up the frame anchor if it isn't already
bool has_last_Java_frame = thread->has_last_Java_frame();
if (!has_last_Java_frame) {
intptr_t *sp = thread->zero_stack()->sp();
ZeroFrame *frame = thread->top_zero_frame();
while (frame) {
if (frame->is_shark_frame())
break;
if (frame->is_interpreter_frame()) {
interpreterState istate =
frame->as_interpreter_frame()->interpreter_state();
if (istate->self_link() == istate)
break;
}
sp = ((intptr_t *) frame) + 1;
frame = frame->next();
}
if (frame == NULL)
fatal("unrecoverable stack overflow");
thread->set_last_Java_frame(frame, sp);
}
// Throw the exception
switch (thread->thread_state()) {
case _thread_in_Java:
InterpreterRuntime::throw_StackOverflowError(thread);
break;
case _thread_in_vm:
Exceptions::throw_stack_overflow_exception(thread, __FILE__, __LINE__);
break;
default:
ShouldNotReachHere();
}
// Reset the frame anchor if necessary
if (!has_last_Java_frame)
thread->reset_last_Java_frame();
}
void doit() {
ResourceMark rmark; // _thread != Thread::current()
RegisterMap rm(_thread, false);
// There can be a race condition between a VM_Operation reaching a safepoint
// and the target thread exiting from Java execution.
// We must recheck the last Java frame still exists.
if (!_thread->is_exiting() && _thread->has_last_Java_frame()) {
javaVFrame* vf = _thread->last_java_vframe(&rm);
assert(vf != NULL, "must have last java frame");
Method* method = vf->method();
_method_id = method->jmethod_id();
_bci = vf->bci();
} else {
// Clear current location as the target thread has no Java frames anymore.
_method_id = (jmethodID)NULL;
_bci = 0;
}
}
// For Forte Analyzer AsyncGetCallTrace profiling support - thread is
// currently interrupted by SIGPROF
bool JavaThread::pd_get_top_frame_for_signal_handler(frame* fr_addr,
void* ucontext, bool isInJava) {
assert(Thread::current() == this, "caller must be current thread");
assert(this->is_Java_thread(), "must be JavaThread");
JavaThread* jt = (JavaThread *)this;
// If we have a last_Java_frame, then we should use it even if
// isInJava == true. It should be more reliable than ucontext info.
if (jt->has_last_Java_frame()) {
*fr_addr = jt->pd_last_frame();
return true;
}
// At this point, we don't have a last_Java_frame, so
// we try to glean some information out of the ucontext
// if we were running Java code when SIGPROF came in.
if (isInJava) {
ucontext_t* uc = (ucontext_t*) ucontext;
intptr_t* ret_fp;
intptr_t* ret_sp;
ExtendedPC addr = os::Solaris::fetch_frame_from_ucontext(this, uc,
&ret_sp, &ret_fp);
if (addr.contained_pc() == NULL || ret_sp == NULL || ret_fp == NULL) {
// ucontext wasn't useful
return false;
}
frame ret_frame(ret_sp, ret_fp, addr.pc());
if (!ret_frame.safe_for_sender(jt)) {
// nothing else to try if the frame isn't good
return false;
}
*fr_addr = ret_frame;
return true;
}
// nothing else to try
return false;
}
extern "C" void ps() { // print stack
if (Thread::current() == NULL) return;
Command c("ps");
// Prints the stack of the current Java thread
JavaThread* p = JavaThread::active();
tty->print(" for thread: ");
p->print();
tty->cr();
if (p->has_last_Java_frame()) {
// If the last_Java_fp is set we are in C land and
// can call the standard stack_trace function.
#ifdef PRODUCT
p->print_stack();
} else {
tty->print_cr("Cannot find the last Java frame, printing stack disabled.");
#else // !PRODUCT
p->trace_stack();
} else {
extern "C" void ps() { // print stack
Command c("ps");
// Prints the stack of the current Java thread
JavaThread* p = JavaThread::active();
tty->print(" for thread: ");
p->print();
tty->cr();
if (p->has_last_Java_frame()) {
// If the last_Java_fp is set we are in C land and
// can call the standard stack_trace function.
p->trace_stack();
} else {
frame f = os::current_frame();
RegisterMap reg_map(p);
f = f.sender(®_map);
tty->print("(guessing starting frame id=%#p based on current fp)\n", f.id());
p->trace_stack_from(vframe::new_vframe(&f, ®_map, p));
pd_ps(f);
}
}
// true when the thread was suspended with a pointer to the last Java frame.
bool has_last_frame() {
return _thread->has_last_Java_frame();
}
// For Forte Analyzer AsyncGetCallTrace profiling support - thread is
// currently interrupted by SIGPROF
bool JavaThread::pd_get_top_frame_for_signal_handler(frame* fr_addr,
void* ucontext,
bool isInJava) {
assert(Thread::current() == this, "caller must be current thread");
assert(this->is_Java_thread(), "must be JavaThread");
JavaThread* jt = (JavaThread *)this;
if (!isInJava) {
// make_walkable flushes register windows and grabs last_Java_pc
// which can not be done if the ucontext sp matches last_Java_sp
// stack walking utilities assume last_Java_pc set if marked flushed
jt->frame_anchor()->make_walkable(jt);
}
// If we have a walkable last_Java_frame, then we should use it
// even if isInJava == true. It should be more reliable than
// ucontext info.
if (jt->has_last_Java_frame() && jt->frame_anchor()->walkable()) {
*fr_addr = jt->pd_last_frame();
return true;
}
ucontext_t* uc = (ucontext_t*) ucontext;
// At this point, we don't have a walkable last_Java_frame, so
// we try to glean some information out of the ucontext.
intptr_t* ret_sp;
ExtendedPC addr =
os::fetch_frame_from_context(uc, &ret_sp,
NULL /* ret_fp only used on X86 */);
if (addr.pc() == NULL || ret_sp == NULL) {
// ucontext wasn't useful
return false;
}
#if INCLUDE_CDS
if (UseSharedSpaces && MetaspaceShared::is_in_shared_region(addr.pc(), MetaspaceShared::md)) {
// In the middle of a trampoline call. Bail out for safety.
// This happens rarely so shouldn't affect profiling.
return false;
}
#endif
// we were running Java code when SIGPROF came in
if (isInJava) {
// If we have a last_Java_sp, then the SIGPROF signal caught us
// right when we were transitioning from _thread_in_Java to a new
// JavaThreadState. We use last_Java_sp instead of the sp from
// the ucontext since it should be more reliable.
if (jt->has_last_Java_frame()) {
ret_sp = jt->last_Java_sp();
}
// Implied else: we don't have a last_Java_sp so we use what we
// got from the ucontext.
frame ret_frame(ret_sp, frame::unpatchable, addr.pc());
if (!ret_frame.safe_for_sender(jt)) {
// nothing else to try if the frame isn't good
return false;
}
*fr_addr = ret_frame;
return true;
}
// At this point, we know we weren't running Java code. We might
// have a last_Java_sp, but we don't have a walkable frame.
// However, we might still be able to construct something useful
// if the thread was running native code.
if (jt->has_last_Java_frame()) {
assert(!jt->frame_anchor()->walkable(), "case covered above");
if (jt->thread_state() == _thread_in_native) {
frame ret_frame(jt->last_Java_sp(), frame::unpatchable, addr.pc());
if (!ret_frame.safe_for_sender(jt)) {
// nothing else to try if the frame isn't good
return false;
}
*fr_addr = ret_frame;
return true;
}
}
// nothing else to try
return false;
}
void AsyncGetCallTrace(ASGCT_CallTrace *trace, jint depth, void* ucontext) {
// This is if'd out because we no longer use thread suspension.
// However if someone wanted to backport this to a 5.0 jvm then this
// code would be important.
#if 0
if (SafepointSynchronize::is_synchronizing()) {
// The safepoint mechanism is trying to synchronize all the threads.
// Since this can involve thread suspension, it is not safe for us
// to be here. We can reduce the deadlock risk window by quickly
// returning to the SIGPROF handler. However, it is still possible
// for VMThread to catch us here or in the SIGPROF handler. If we
// are suspended while holding a resource and another thread blocks
// on that resource in the SIGPROF handler, then we will have a
// three-thread deadlock (VMThread, this thread, the other thread).
trace->num_frames = ticks_safepoint; // -10
return;
}
#endif
JavaThread* thread;
if (trace->env_id == NULL ||
(thread = JavaThread::thread_from_jni_environment(trace->env_id)) == NULL ||
thread->is_exiting()) {
// bad env_id, thread has exited or thread is exiting
trace->num_frames = ticks_thread_exit; // -8
return;
}
if (thread->in_deopt_handler()) {
// thread is in the deoptimization handler so return no frames
trace->num_frames = ticks_deopt; // -9
return;
}
assert(JavaThread::current() == thread,
"AsyncGetCallTrace must be called by the current interrupted thread");
if (!JvmtiExport::should_post_class_load()) {
trace->num_frames = ticks_no_class_load; // -1
return;
}
if (Universe::heap()->is_gc_active()) {
trace->num_frames = ticks_GC_active; // -2
return;
}
switch (thread->thread_state()) {
case _thread_new:
case _thread_uninitialized:
case _thread_new_trans:
// We found the thread on the threads list above, but it is too
// young to be useful so return that there are no Java frames.
trace->num_frames = 0;
break;
case _thread_in_native:
case _thread_in_native_trans:
case _thread_blocked:
case _thread_blocked_trans:
case _thread_in_vm:
case _thread_in_vm_trans:
{
frame fr;
// param isInJava == false - indicate we aren't in Java code
if (!thread->pd_get_top_frame_for_signal_handler(&fr, ucontext, false)) {
trace->num_frames = ticks_unknown_not_Java; // -3 unknown frame
} else {
if (!thread->has_last_Java_frame()) {
trace->num_frames = 0; // No Java frames
} else {
trace->num_frames = ticks_not_walkable_not_Java; // -4 non walkable frame by default
forte_fill_call_trace_given_top(thread, trace, depth, fr);
// This assert would seem to be valid but it is not.
// It would be valid if we weren't possibly racing a gc
// thread. A gc thread can make a valid interpreted frame
// look invalid. It's a small window but it does happen.
// The assert is left here commented out as a reminder.
// assert(trace->num_frames != ticks_not_walkable_not_Java, "should always be walkable");
}
}
}
break;
case _thread_in_Java:
case _thread_in_Java_trans:
{
frame fr;
// param isInJava == true - indicate we are in Java code
if (!thread->pd_get_top_frame_for_signal_handler(&fr, ucontext, true)) {
trace->num_frames = ticks_unknown_Java; // -5 unknown frame
} else {
trace->num_frames = ticks_not_walkable_Java; // -6, non walkable frame by default
forte_fill_call_trace_given_top(thread, trace, depth, fr);
}
}
break;
default:
// Unknown thread state
trace->num_frames = ticks_unknown_state; // -7
break;
}
}
bool JavaThread::pd_get_top_frame(frame* fr_addr,
void* ucontext, bool isInJava, bool makeWalkable) {
assert(this->is_Java_thread(), "must be JavaThread");
JavaThread* jt = (JavaThread *)this;
if (!isInJava && makeWalkable) {
// make_walkable flushes register windows and grabs last_Java_pc
// which can not be done if the ucontext sp matches last_Java_sp
// stack walking utilities assume last_Java_pc set if marked flushed
jt->frame_anchor()->make_walkable(jt);
}
// If we have a walkable last_Java_frame, then we should use it
// even if isInJava == true. It should be more reliable than
// ucontext info.
if (jt->has_last_Java_frame() && jt->frame_anchor()->walkable()) {
*fr_addr = jt->pd_last_frame();
return true;
}
ucontext_t* uc = (ucontext_t*) ucontext;
// At this point, we don't have a walkable last_Java_frame, so
// we try to glean some information out of the ucontext.
intptr_t* ret_sp;
ExtendedPC addr = os::Solaris::fetch_frame_from_ucontext(this, uc,
&ret_sp, NULL /* ret_fp only used on Solaris X86 */);
if (addr.pc() == NULL || ret_sp == NULL) {
// ucontext wasn't useful
return false;
}
#if INCLUDE_CDS
if (UseSharedSpaces && MetaspaceShared::is_in_shared_region(addr.pc(), MetaspaceShared::md)) {
// In the middle of a trampoline call. Bail out for safety.
// This happens rarely so shouldn't affect profiling.
return false;
}
#endif
frame ret_frame(ret_sp, frame::unpatchable, addr.pc());
// we were running Java code when SIGPROF came in
if (isInJava) {
// If the frame we got is safe then it is most certainly valid
if (ret_frame.safe_for_sender(jt)) {
*fr_addr = ret_frame;
return true;
}
// If it isn't safe then we can try several things to try and get
// a good starting point.
//
// On sparc the frames are almost certainly walkable in the sense
// of sp/fp linkages. However because of recycling of windows if
// a piece of code does multiple save's where the initial save creates
// a real frame with a return pc and the succeeding save's are used to
// simply get free registers and have no real pc then the pc linkage on these
// "inner" temporary frames will be bogus.
// Since there is in general only a nesting level like
// this one deep in general we'll try and unwind such an "inner" frame
// here ourselves and see if it makes sense
frame unwind_frame(ret_frame.fp(), frame::unpatchable, addr.pc());
if (unwind_frame.safe_for_sender(jt)) {
*fr_addr = unwind_frame;
return true;
}
// Well that didn't work. Most likely we're toast on this tick
// The previous code would try this. I think it is dubious in light
// of changes to safe_for_sender and the unwind trick above but
// if it gets us a safe frame who wants to argue.
// If we have a last_Java_sp, then the SIGPROF signal caught us
// right when we were transitioning from _thread_in_Java to a new
// JavaThreadState. We use last_Java_sp instead of the sp from
// the ucontext since it should be more reliable.
if (jt->has_last_Java_frame()) {
ret_sp = jt->last_Java_sp();
frame ret_frame2(ret_sp, frame::unpatchable, addr.pc());
if (ret_frame2.safe_for_sender(jt)) {
*fr_addr = ret_frame2;
return true;
}
}
// This is the best we can do. We will only be able to decode the top frame
*fr_addr = ret_frame;
return true;
}
// At this point, we know we weren't running Java code. We might
// have a last_Java_sp, but we don't have a walkable frame.
// However, we might still be able to construct something useful
// if the thread was running native code.
if (jt->has_last_Java_frame()) {
assert(!jt->frame_anchor()->walkable(), "case covered above");
frame ret_frame(jt->last_Java_sp(), frame::unpatchable, addr.pc());
*fr_addr = ret_frame;
return true;
}
// nothing else to try but what we found initially
*fr_addr = ret_frame;
return true;
}
JNIEXPORT
void AsyncGetCallTrace(ASGCT_CallTrace *trace, jint depth, void* ucontext) {
JavaThread* thread;
if (trace->env_id == NULL ||
(thread = JavaThread::thread_from_jni_environment(trace->env_id)) == NULL ||
thread->is_exiting()) {
// bad env_id, thread has exited or thread is exiting
trace->num_frames = ticks_thread_exit; // -8
return;
}
if (thread->in_deopt_handler()) {
// thread is in the deoptimization handler so return no frames
trace->num_frames = ticks_deopt; // -9
return;
}
assert(JavaThread::current() == thread,
"AsyncGetCallTrace must be called by the current interrupted thread");
if (!JvmtiExport::should_post_class_load()) {
trace->num_frames = ticks_no_class_load; // -1
return;
}
if (Universe::heap()->is_gc_active()) {
trace->num_frames = ticks_GC_active; // -2
return;
}
switch (thread->thread_state()) {
case _thread_new:
case _thread_uninitialized:
case _thread_new_trans:
// We found the thread on the threads list above, but it is too
// young to be useful so return that there are no Java frames.
trace->num_frames = 0;
break;
case _thread_in_native:
case _thread_in_native_trans:
case _thread_blocked:
case _thread_blocked_trans:
case _thread_in_vm:
case _thread_in_vm_trans:
{
frame fr;
// param isInJava == false - indicate we aren't in Java code
if (!thread->pd_get_top_frame_for_signal_handler(&fr, ucontext, false)) {
trace->num_frames = ticks_unknown_not_Java; // -3 unknown frame
} else {
if (!thread->has_last_Java_frame()) {
trace->num_frames = 0; // No Java frames
} else {
trace->num_frames = ticks_not_walkable_not_Java; // -4 non walkable frame by default
forte_fill_call_trace_given_top(thread, trace, depth, fr);
// This assert would seem to be valid but it is not.
// It would be valid if we weren't possibly racing a gc
// thread. A gc thread can make a valid interpreted frame
// look invalid. It's a small window but it does happen.
// The assert is left here commented out as a reminder.
// assert(trace->num_frames != ticks_not_walkable_not_Java, "should always be walkable");
}
}
}
break;
case _thread_in_Java:
case _thread_in_Java_trans:
{
frame fr;
// param isInJava == true - indicate we are in Java code
if (!thread->pd_get_top_frame_for_signal_handler(&fr, ucontext, true)) {
trace->num_frames = ticks_unknown_Java; // -5 unknown frame
} else {
trace->num_frames = ticks_not_walkable_Java; // -6, non walkable frame by default
forte_fill_call_trace_given_top(thread, trace, depth, fr);
}
}
break;
default:
// Unknown thread state
trace->num_frames = ticks_unknown_state; // -7
break;
}
}