jdk-sandbox: comparison src/hotspot/share/runtime/handshake.cpp

equal deleted inserted replaced

-:d9753e3db0c6
+:9fdfe5ca0e5e
 #include "logging/log.hpp"
 #include "logging/logStream.hpp"
 #include "memory/resourceArea.hpp"
 #include "runtime/handshake.hpp"
 #include "runtime/interfaceSupport.inline.hpp"
+#include "runtime/orderAccess.hpp"
 #include "runtime/osThread.hpp"
 #include "runtime/semaphore.inline.hpp"
 #include "runtime/task.hpp"
 #include "runtime/timerTrace.hpp"
 #include "runtime/thread.hpp"
 virtual void do_handshake(JavaThread* thread) = 0;
 virtual void cancel_handshake(JavaThread* thread) = 0;
 };
 class HandshakeThreadsOperation: public HandshakeOperation {
-Semaphore _done;
+static Semaphore _done;
 ThreadClosure* _thread_cl;
 public:
-HandshakeThreadsOperation(ThreadClosure* cl) : _done(0), _thread_cl(cl) {}
+HandshakeThreadsOperation(ThreadClosure* cl) : _thread_cl(cl) {}
 void do_handshake(JavaThread* thread);
 void cancel_handshake(JavaThread* thread) { _done.signal(); };
 bool thread_has_completed() { return _done.trywait(); }
-};
+#ifdef ASSERT
+void check_state() {
+assert(!_done.trywait(), "Must be zero");
+}
+#endif
+};
+Semaphore HandshakeThreadsOperation::_done(0);
 class VM_Handshake: public VM_Operation {
-HandshakeThreadsOperation* const _op;
 const jlong _handshake_timeout;
 public:
 bool evaluate_at_safepoint() const { return false; }
 bool evaluate_concurrently() const { return false; }
 protected:
+HandshakeThreadsOperation* const _op;
 VM_Handshake(HandshakeThreadsOperation* op) :
 _op(op),
 _handshake_timeout(TimeHelper::millis_to_counter(HandshakeTimeout)) {}
 }
 log_stream.flush();
 fatal("Handshake operation timed out");
 }
 class VM_HandshakeOneThread: public VM_Handshake {
 JavaThread* _target;
 bool _thread_alive;
 public:
 VM_HandshakeOneThread(HandshakeThreadsOperation* op, JavaThread* target) :
 VM_Handshake(op), _target(target), _thread_alive(false) {}
 void doit() {
+DEBUG_ONLY(_op->check_state();)
 TraceTime timer("Performing single-target operation (vmoperation doit)", TRACETIME_LOG(Info, handshake));
 {
 ThreadsListHandle tlh;
 if (tlh.includes(_target)) {
 // it has been removed from the ThreadsList. So we should just keep
 // looping here until while below returns false. If we have a bug,
 // then we hang here, which is good for debugging.
 }
 } while (!poll_for_completed_thread());
+DEBUG_ONLY(_op->check_state();)
 }
 VMOp_Type type() const { return VMOp_HandshakeOneThread; }
 bool thread_alive() const { return _thread_alive; }
 class VM_HandshakeAllThreads: public VM_Handshake {
 public:
 VM_HandshakeAllThreads(HandshakeThreadsOperation* op) : VM_Handshake(op) {}
 void doit() {
+DEBUG_ONLY(_op->check_state();)
 TraceTime timer("Performing operation (vmoperation doit)", TRACETIME_LOG(Info, handshake));
 int number_of_threads_issued = 0;
 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thr = jtiwh.next(); ) {
 set_handshake(thr);
 while (poll_for_completed_thread()) {
 // Includes canceled operations by exiting threads.
 number_of_threads_completed++;
 }
-} while (number_of_threads_issued != number_of_threads_completed);
+} while (number_of_threads_issued > number_of_threads_completed);
+assert(number_of_threads_issued == number_of_threads_completed, "Must be the same");
+DEBUG_ONLY(_op->check_state();)
 }
 VMOp_Type type() const { return VMOp_HandshakeAllThreads; }
 };
 VMOp_Type type() const { return VMOp_HandshakeFallback; }
 bool thread_alive() const { return _thread_alive; }
 };
-#undef ALL_JAVA_THREADS
 void HandshakeThreadsOperation::do_handshake(JavaThread* thread) {
 ResourceMark rm;
 FormatBufferResource message("Operation for thread " PTR_FORMAT ", is_vm_thread: %s",
 p2i(thread), BOOL_TO_STR(Thread::current()->is_VM_thread()));
 TraceTime timer(message, TRACETIME_LOG(Debug, handshake, task));
 VMThread::execute(&op);
 return op.thread_alive();
 }
 }
-HandshakeState::HandshakeState() : _operation(NULL), _semaphore(1), _vmthread_holds_semaphore(false), _thread_in_process_handshake(false) {}
+HandshakeState::HandshakeState() : _operation(NULL), _semaphore(1), _thread_in_process_handshake(false) {}
 void HandshakeState::set_operation(JavaThread* target, HandshakeOperation* op) {
 _operation = op;
 SafepointMechanism::arm_local_poll(target);
 }
 SafepointMechanism::disarm_local_poll(target);
 }
 void HandshakeState::process_self_inner(JavaThread* thread) {
 assert(Thread::current() == thread, "should call from thread");
+if (thread->is_terminated()) {
+// If thread is not on threads list but armed, cancel.
+thread->cancel_handshake();
+return;
+}
 CautiouslyPreserveExceptionMark pem(thread);
 ThreadInVMForHandshake tivm(thread);
 if (!_semaphore.trywait()) {
 _semaphore.wait_with_safepoint_check(thread);
 }
-if (has_operation()) {
+HandshakeOperation* op = OrderAccess::load_acquire(&_operation);
-HandshakeOperation* op = _operation;
+if (op != NULL) {
+// Disarm before execute the operation
 clear_handshake(thread);
-if (op != NULL) {
+op->do_handshake(thread);
-op->do_handshake(thread);
-}
 }
 _semaphore.signal();
 }
 void HandshakeState::cancel_inner(JavaThread* thread) {
 assert(Thread::current() == thread, "should call from thread");
 assert(thread->thread_state() == _thread_in_vm, "must be in vm state");
-#ifdef DEBUG
-{
-ThreadsListHandle tlh;
-assert(!tlh.includes(_target), "java thread must not be on threads list");
-}
-#endif
 HandshakeOperation* op = _operation;
 clear_handshake(thread);
 if (op != NULL) {
 op->cancel_handshake(thread);
 }
 bool HandshakeState::vmthread_can_process_handshake(JavaThread* target) {
 return SafepointSynchronize::safepoint_safe(target, target->thread_state());
 }
 bool HandshakeState::claim_handshake_for_vmthread() {
-if (_semaphore.trywait()) {
+if (!_semaphore.trywait()) {
-if (has_operation()) {
+return false;
-_vmthread_holds_semaphore = true;
+}
-} else {
+if (has_operation()) {
-_semaphore.signal();
+return true;
 }
-}
+_semaphore.signal();
-return _vmthread_holds_semaphore;
+return false;
 }
 void HandshakeState::process_by_vmthread(JavaThread* target) {
 assert(Thread::current()->is_VM_thread(), "should call from vm thread");
 if (!vmthread_can_process_handshake(target)) {
 // JT is observed in an unsafe state, it must notice the handshake itself
 return;
 }
+// Claim the semaphore if there still an operation to be executed.
+if (!claim_handshake_for_vmthread()) {
+return;
+}
 // If we own the semaphore at this point and while owning the semaphore
 // can observe a safe state the thread cannot possibly continue without
 // getting caught by the semaphore.
-if (claim_handshake_for_vmthread() && vmthread_can_process_handshake(target)) {
+if (vmthread_can_process_handshake(target)) {
 guarantee(!_semaphore.trywait(), "we should already own the semaphore");
 _operation->do_handshake(target);
+// Disarm after VM thread have executed the operation.
 clear_handshake(target);
-_vmthread_holds_semaphore = false;
 // Release the thread
-_semaphore.signal();
+}
-}
-}
+_semaphore.signal();
+}

changeset 50626	9fdfe5ca0e5e
parent 50192	8bc79d2d1568
child 50921	7f462e8383f6