--- handshake.cpp +++ handshake.cpp @@ -52,6 +51,7 @@ void do_handshake(JavaThread* thread); bool thread_has_completed() { return _done.trywait(); } bool executed() const { return _executed; } + const char* name() { return _handshake_cl->name(); } #ifdef ASSERT void check_state() { @@ -114,20 +126,25 @@ void doit() { DEBUG_ONLY(_op->check_state();) - TraceTime timer("Finished executing single-target operation (VM_HandshakeOneThread::doit)", TRACETIME_LOG(Info, handshake)); + + jlong start_time_ns = 0; + if (log_is_enabled(Info, handshake)) { + start_time_ns = os::javaTimeNanos(); + } ThreadsListHandle tlh; if (tlh.includes(_target)) { set_handshake(_target); } else { - log_trace(handshake)("JavaThread " INTPTR_FORMAT " is not alive", p2i(_target)); + log_handshake_info(start_time_ns, _op->name(), 0, 0, "(thread dead)"); return; } log_trace(handshake)("JavaThread " INTPTR_FORMAT " signaled, begin attempt to process by VMThtread", p2i(_target)); - jlong start_time = os::elapsed_counter(); + jlong timeout_start_time = os::elapsed_counter(); + bool by_vm_thread = false; do { - if (handshake_has_timed_out(start_time)) { + if (handshake_has_timed_out(timeout_start_time)) { handle_timeout(); } @@ -136,10 +153,11 @@ // locked during certain phases. { MutexLocker ml(Threads_lock); - _target->handshake_process_by_vmthread(); + by_vm_thread = _target->handshake_try_process_by_vmThread(); } } while (!poll_for_completed_thread()); DEBUG_ONLY(_op->check_state();) + log_handshake_info(start_time_ns, _op->name(), 1, by_vm_thread ? 1 : 0); } VMOp_Type type() const { return VMOp_HandshakeOneThread; } @@ -153,7 +171,12 @@ void doit() { DEBUG_ONLY(_op->check_state();) - TraceTime timer("Finished executing multi-target operation (VM_HandshakeAllThreads::doit)", TRACETIME_LOG(Info, handshake)); + + jlong start_time_ns = 0; + if (log_is_enabled(Info, handshake)) { + start_time_ns = os::javaTimeNanos(); + } + int handshake_executed_by_vm_thread = 0; JavaThreadIteratorWithHandle jtiwh; int number_of_threads_issued = 0; @@ -163,11 +186,11 @@ } if (number_of_threads_issued < 1) { - log_debug(handshake)("No threads to handshake."); + log_handshake_info(start_time_ns, _op->name(), 0, 0); return; } - log_debug(handshake)("Threads signaled, begin processing blocked threads by VMThtread"); + log_trace(handshake)("Threads signaled, begin processing blocked threads by VMThread"); const jlong start_time = os::elapsed_counter(); int number_of_threads_completed = 0; do { @@ -188,7 +211,9 @@ for (JavaThread *thr = jtiwh.next(); thr != NULL; thr = jtiwh.next()) { // A new thread on the ThreadsList will not have an operation, // hence it is skipped in handshake_process_by_vmthread. - thr->handshake_process_by_vmthread(); + if (thr->handshake_try_process_by_vmThread()) { + handshake_executed_by_vm_thread++; + } } } @@ -217,7 +244,7 @@ _handshake_cl(cl), _target_thread(target), _all_threads(false), _executed(false) {} void doit() { - log_trace(handshake)("VMThread executing VM_HandshakeFallbackOperation"); + log_trace(handshake)("VMThread executing VM_HandshakeFallbackOperation, operation: %s", name()); for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { if (_all_threads || t == _target_thread) { if (t == _target_thread) { @@ -348,37 +381,41 @@ return false; } -void HandshakeState::process_by_vmthread(JavaThread* target) { +bool HandshakeState::try_process_by_vmThread(JavaThread* target) { assert(Thread::current()->is_VM_thread(), "should call from vm thread"); // Threads_lock must be held here, but that is assert()ed in // possibly_vmthread_can_process_handshake(). if (!has_operation()) { // JT has already cleared its handshake - return; + return false; } if (!possibly_vmthread_can_process_handshake(target)) { // JT is observed in an unsafe state, it must notice the handshake itself - return; + return false; } // Claim the semaphore if there still an operation to be executed. if (!claim_handshake_for_vmthread()) { - return; + return false; } // 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. + bool executed = false; if (vmthread_can_process_handshake(target)) { guarantee(!_semaphore.trywait(), "we should already own the semaphore"); log_trace(handshake)("Processing handshake by VMThtread"); _operation->do_handshake(target); // Disarm after VM thread have executed the operation. clear_handshake(target); - // Release the thread + executed = true; } + // Release the thread _semaphore.signal(); + + return executed; } --- handshake.hpp +++ handshake.hpp @@ -88,7 +88,7 @@ } } - void process_by_vmthread(JavaThread* target); + bool try_process_by_vmThread(JavaThread* target); }; #endif // SHARE_RUNTIME_HANDSHAKE_HPP --- thread.hpp +++ thread.hpp @@ -1329,8 +1329,8 @@ _handshake.process_by_self(this); } - void handshake_process_by_vmthread() { - _handshake.process_by_vmthread(this); + bool handshake_try_process_by_vmThread() { + return _handshake.try_process_by_vmThread(this); } // Suspend/resume support for JavaThread