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8234742: Improve handshake logging

Reviewed-by: dholmes, pchilanomate
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robehn committed Dec 4, 2019
1 parent c0ea1e6 commit b31e91cd8d5430eeca382bcb9cf9b67f77b3d0a8
@@ -32,7 +32,6 @@
#include "runtime/osThread.hpp"
#include "runtime/semaphore.inline.hpp"
#include "runtime/task.hpp"
#include "runtime/timerTrace.hpp"
#include "runtime/thread.hpp"
#include "runtime/vmThread.hpp"
#include "utilities/formatBuffer.hpp"
@@ -52,6 +51,7 @@ class HandshakeThreadsOperation: public HandshakeOperation {
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() {
@@ -106,6 +106,18 @@ void VM_Handshake::handle_timeout() {
fatal("Handshake operation timed out");
}

static void log_handshake_info(jlong start_time_ns, const char* name, int targets, int vmt_executed, const char* extra = NULL) {
if (start_time_ns != 0) {
jlong completion_time = os::javaTimeNanos() - start_time_ns;
log_info(handshake)("Handshake \"%s\", Targeted threads: %d, Executed by targeted threads: %d, Total completion time: " JLONG_FORMAT " ns%s%s",
name, targets,
targets - vmt_executed,
completion_time,
extra != NULL ? ", " : "",
extra != NULL ? extra : "");
}
}

class VM_HandshakeOneThread: public VM_Handshake {
JavaThread* _target;
public:
@@ -114,20 +126,25 @@ class VM_HandshakeOneThread: public VM_Handshake {

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 @@ class VM_HandshakeOneThread: public VM_Handshake {
// 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 @@ class VM_HandshakeAllThreads: public VM_Handshake {

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 @@ class VM_HandshakeAllThreads: public VM_Handshake {
}

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 @@ class VM_HandshakeAllThreads: public VM_Handshake {
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++;
}
}
}

@@ -200,6 +225,8 @@ class VM_HandshakeAllThreads: public VM_Handshake {
} 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();)

log_handshake_info(start_time_ns, _op->name(), number_of_threads_issued, handshake_executed_by_vm_thread);
}

VMOp_Type type() const { return VMOp_HandshakeAllThreads; }
@@ -217,7 +244,7 @@ class VM_HandshakeFallbackOperation : public VM_Operation {
_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) {
@@ -233,10 +260,10 @@ class VM_HandshakeFallbackOperation : public VM_Operation {
};

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));
jlong start_time_ns = 0;
if (log_is_enabled(Debug, handshake, task)) {
start_time_ns = os::javaTimeNanos();
}

// Only actually execute the operation for non terminated threads.
if (!thread->is_terminated()) {
@@ -246,6 +273,12 @@ void HandshakeThreadsOperation::do_handshake(JavaThread* thread) {

// Use the semaphore to inform the VM thread that we have completed the operation
_done.signal();

if (start_time_ns != 0) {
jlong completion_time = os::javaTimeNanos() - start_time_ns;
log_debug(handshake, task)("Operation: %s for thread " PTR_FORMAT ", is_vm_thread: %s, completed in " JLONG_FORMAT " ns",
name(), p2i(thread), BOOL_TO_STR(Thread::current()->is_VM_thread()), completion_time);
}
}

void Handshake::execute(HandshakeClosure* thread_cl) {
@@ -348,37 +381,41 @@ bool HandshakeState::claim_handshake_for_vmthread() {
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;
}
@@ -88,7 +88,7 @@ class HandshakeState {
}
}

void process_by_vmthread(JavaThread* target);
bool try_process_by_vmThread(JavaThread* target);
};

#endif // SHARE_RUNTIME_HANDSHAKE_HPP
@@ -1329,8 +1329,8 @@ class JavaThread: public Thread {
_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

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