8371347: Move the ObjectMonitorTable to a separate new file

Reviewed-by: dholmes, coleenp
This commit is contained in:
Fredrik Bredberg 2025-12-15 08:55:08 +00:00
parent 895232fc65
commit ad6611a9a3
3 changed files with 386 additions and 285 deletions

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@ -0,0 +1,308 @@
/*
* Copyright (c) 2024, 2025, Oracle and/or its affiliates. All rights reserved.
* 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
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "logging/log.hpp"
#include "runtime/interfaceSupport.inline.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/objectMonitorTable.hpp"
#include "runtime/safepoint.hpp"
#include "runtime/thread.hpp"
#include "runtime/timerTrace.hpp"
#include "runtime/trimNativeHeap.hpp"
#include "utilities/concurrentHashTableTasks.inline.hpp"
#include "utilities/globalDefinitions.hpp"
// -----------------------------------------------------------------------------
// ConcurrentHashTable storing links from objects to ObjectMonitors
using ConcurrentTable = ConcurrentHashTable<ObjectMonitorTableConfig, mtObjectMonitor>;
static ConcurrentTable* _table = nullptr;
static volatile size_t _items_count = 0;
static size_t _table_size = 0;
static volatile bool _resize = false;
class ObjectMonitorTableConfig : public AllStatic {
public:
using Value = ObjectMonitor*;
static uintx get_hash(Value const& value, bool* is_dead) {
return (uintx)value->hash();
}
static void* allocate_node(void* context, size_t size, Value const& value) {
ObjectMonitorTable::inc_items_count();
return AllocateHeap(size, mtObjectMonitor);
};
static void free_node(void* context, void* memory, Value const& value) {
ObjectMonitorTable::dec_items_count();
FreeHeap(memory);
}
};
class Lookup : public StackObj {
oop _obj;
public:
explicit Lookup(oop obj) : _obj(obj) {}
uintx get_hash() const {
uintx hash = _obj->mark().hash();
assert(hash != 0, "should have a hash");
return hash;
}
bool equals(ObjectMonitor** value) {
assert(*value != nullptr, "must be");
return (*value)->object_refers_to(_obj);
}
bool is_dead(ObjectMonitor** value) {
assert(*value != nullptr, "must be");
return false;
}
};
class LookupMonitor : public StackObj {
ObjectMonitor* _monitor;
public:
explicit LookupMonitor(ObjectMonitor* monitor) : _monitor(monitor) {}
uintx get_hash() const {
return _monitor->hash();
}
bool equals(ObjectMonitor** value) {
return (*value) == _monitor;
}
bool is_dead(ObjectMonitor** value) {
assert(*value != nullptr, "must be");
return (*value)->object_is_dead();
}
};
void ObjectMonitorTable::inc_items_count() {
AtomicAccess::inc(&_items_count, memory_order_relaxed);
}
void ObjectMonitorTable::dec_items_count() {
AtomicAccess::dec(&_items_count, memory_order_relaxed);
}
double ObjectMonitorTable::get_load_factor() {
size_t count = AtomicAccess::load(&_items_count);
return (double)count / (double)_table_size;
}
size_t ObjectMonitorTable::table_size(Thread* current) {
return ((size_t)1) << _table->get_size_log2(current);
}
size_t ObjectMonitorTable::max_log_size() {
// TODO[OMTable]: Evaluate the max size.
// TODO[OMTable]: Need to fix init order to use Universe::heap()->max_capacity();
// Using MaxHeapSize directly this early may be wrong, and there
// are definitely rounding errors (alignment).
const size_t max_capacity = MaxHeapSize;
const size_t min_object_size = CollectedHeap::min_dummy_object_size() * HeapWordSize;
const size_t max_objects = max_capacity / MAX2(MinObjAlignmentInBytes, checked_cast<int>(min_object_size));
const size_t log_max_objects = log2i_graceful(max_objects);
return MAX2(MIN2<size_t>(SIZE_BIG_LOG2, log_max_objects), min_log_size());
}
// ~= log(AvgMonitorsPerThreadEstimate default)
size_t ObjectMonitorTable::min_log_size() {
return 10;
}
template<typename V>
size_t ObjectMonitorTable::clamp_log_size(V log_size) {
return MAX2(MIN2(log_size, checked_cast<V>(max_log_size())), checked_cast<V>(min_log_size()));
}
size_t ObjectMonitorTable::initial_log_size() {
const size_t estimate = log2i(MAX2(os::processor_count(), 1)) + log2i(MAX2(AvgMonitorsPerThreadEstimate, size_t(1)));
return clamp_log_size(estimate);
}
size_t ObjectMonitorTable::grow_hint() {
return ConcurrentTable::DEFAULT_GROW_HINT;
}
void ObjectMonitorTable::create() {
_table = new ConcurrentTable(initial_log_size(), max_log_size(), grow_hint());
_items_count = 0;
_table_size = table_size(Thread::current());
_resize = false;
}
void ObjectMonitorTable::verify_monitor_get_result(oop obj, ObjectMonitor* monitor) {
#ifdef ASSERT
if (SafepointSynchronize::is_at_safepoint()) {
bool has_monitor = obj->mark().has_monitor();
assert(has_monitor == (monitor != nullptr),
"Inconsistency between markWord and ObjectMonitorTable has_monitor: %s monitor: " PTR_FORMAT,
BOOL_TO_STR(has_monitor), p2i(monitor));
}
#endif
}
ObjectMonitor* ObjectMonitorTable::monitor_get(Thread* current, oop obj) {
ObjectMonitor* result = nullptr;
Lookup lookup_f(obj);
auto found_f = [&](ObjectMonitor** found) {
assert((*found)->object_peek() == obj, "must be");
result = *found;
};
_table->get(current, lookup_f, found_f);
verify_monitor_get_result(obj, result);
return result;
}
void ObjectMonitorTable::try_notify_grow() {
if (!_table->is_max_size_reached() && !AtomicAccess::load(&_resize)) {
AtomicAccess::store(&_resize, true);
if (Service_lock->try_lock()) {
Service_lock->notify();
Service_lock->unlock();
}
}
}
bool ObjectMonitorTable::should_grow() {
return get_load_factor() > GROW_LOAD_FACTOR && !_table->is_max_size_reached();
}
bool ObjectMonitorTable::should_resize() {
return should_grow() || should_shrink() || AtomicAccess::load(&_resize);
}
template <typename Task, typename... Args>
bool ObjectMonitorTable::run_task(JavaThread* current, Task& task, const char* task_name, Args&... args) {
if (task.prepare(current)) {
log_trace(monitortable)("Started to %s", task_name);
TraceTime timer(task_name, TRACETIME_LOG(Debug, monitortable, perf));
while (task.do_task(current, args...)) {
task.pause(current);
{
ThreadBlockInVM tbivm(current);
}
task.cont(current);
}
task.done(current);
return true;
}
return false;
}
bool ObjectMonitorTable::grow(JavaThread* current) {
ConcurrentTable::GrowTask grow_task(_table);
if (run_task(current, grow_task, "Grow")) {
_table_size = table_size(current);
log_info(monitortable)("Grown to size: %zu", _table_size);
return true;
}
return false;
}
bool ObjectMonitorTable::clean(JavaThread* current) {
ConcurrentTable::BulkDeleteTask clean_task(_table);
auto is_dead = [&](ObjectMonitor** monitor) {
return (*monitor)->object_is_dead();
};
auto do_nothing = [&](ObjectMonitor** monitor) {};
NativeHeapTrimmer::SuspendMark sm("ObjectMonitorTable");
return run_task(current, clean_task, "Clean", is_dead, do_nothing);
}
bool ObjectMonitorTable::resize(JavaThread* current) {
LogTarget(Info, monitortable) lt;
bool success = false;
if (should_grow()) {
lt.print("Start growing with load factor %f", get_load_factor());
success = grow(current);
} else {
if (!_table->is_max_size_reached() && AtomicAccess::load(&_resize)) {
lt.print("WARNING: Getting resize hints with load factor %f", get_load_factor());
}
lt.print("Start cleaning with load factor %f", get_load_factor());
success = clean(current);
}
AtomicAccess::store(&_resize, false);
return success;
}
ObjectMonitor* ObjectMonitorTable::monitor_put_get(Thread* current, ObjectMonitor* monitor, oop obj) {
// Enter the monitor into the concurrent hashtable.
ObjectMonitor* result = monitor;
Lookup lookup_f(obj);
auto found_f = [&](ObjectMonitor** found) {
assert((*found)->object_peek() == obj, "must be");
result = *found;
};
bool grow;
_table->insert_get(current, lookup_f, monitor, found_f, &grow);
verify_monitor_get_result(obj, result);
if (grow) {
try_notify_grow();
}
return result;
}
bool ObjectMonitorTable::remove_monitor_entry(Thread* current, ObjectMonitor* monitor) {
LookupMonitor lookup_f(monitor);
return _table->remove(current, lookup_f);
}
bool ObjectMonitorTable::contains_monitor(Thread* current, ObjectMonitor* monitor) {
LookupMonitor lookup_f(monitor);
bool result = false;
auto found_f = [&](ObjectMonitor** found) {
result = true;
};
_table->get(current, lookup_f, found_f);
return result;
}
void ObjectMonitorTable::print_on(outputStream* st) {
auto printer = [&] (ObjectMonitor** entry) {
ObjectMonitor* om = *entry;
oop obj = om->object_peek();
st->print("monitor=" PTR_FORMAT ", ", p2i(om));
st->print("object=" PTR_FORMAT, p2i(obj));
assert(obj->mark().hash() == om->hash(), "hash must match");
st->cr();
return true;
};
if (SafepointSynchronize::is_at_safepoint()) {
_table->do_safepoint_scan(printer);
} else {
_table->do_scan(Thread::current(), printer);
}
}

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@ -0,0 +1,77 @@
/*
* Copyright (c) 2024, 2025, Oracle and/or its affiliates. All rights reserved.
* 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
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#ifndef SHARE_RUNTIME_OBJECTMONITORTABLE_HPP
#define SHARE_RUNTIME_OBJECTMONITORTABLE_HPP
#include "memory/allStatic.hpp"
#include "oops/oopsHierarchy.hpp"
#include "utilities/globalDefinitions.hpp"
class JavaThread;
class ObjectMonitor;
class ObjectMonitorTableConfig;
class outputStream;
class Thread;
class ObjectMonitorTable : AllStatic {
friend class ObjectMonitorTableConfig;
private:
static void inc_items_count();
static void dec_items_count();
static double get_load_factor();
static size_t table_size(Thread* current);
static size_t max_log_size();
static size_t min_log_size();
template <typename V>
static size_t clamp_log_size(V log_size);
static size_t initial_log_size();
static size_t grow_hint();
public:
static void create();
static void verify_monitor_get_result(oop obj, ObjectMonitor* monitor);
static ObjectMonitor* monitor_get(Thread* current, oop obj);
static void try_notify_grow();
static bool should_shrink() { return false; } // Not implemented
static constexpr double GROW_LOAD_FACTOR = 0.75;
static bool should_grow();
static bool should_resize();
template <typename Task, typename... Args>
static bool run_task(JavaThread* current, Task& task, const char* task_name, Args&... args);
static bool grow(JavaThread* current);
static bool clean(JavaThread* current);
static bool resize(JavaThread* current);
static ObjectMonitor* monitor_put_get(Thread* current, ObjectMonitor* monitor, oop obj);
static bool remove_monitor_entry(Thread* current, ObjectMonitor* monitor);
static bool contains_monitor(Thread* current, ObjectMonitor* monitor);
static void print_on(outputStream* st);
};
#endif // SHARE_RUNTIME_OBJECTMONITORTABLE_HPP

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@ -44,6 +44,7 @@
#include "runtime/lockStack.inline.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/objectMonitor.inline.hpp"
#include "runtime/objectMonitorTable.hpp"
#include "runtime/os.inline.hpp"
#include "runtime/osThread.hpp"
#include "runtime/safepointMechanism.inline.hpp"
@ -1470,291 +1471,6 @@ void ObjectSynchronizer::log_in_use_monitor_details(outputStream* out, bool log_
out->flush();
}
// -----------------------------------------------------------------------------
// ConcurrentHashTable storing links from objects to ObjectMonitors
class ObjectMonitorTable : AllStatic {
struct Config {
using Value = ObjectMonitor*;
static uintx get_hash(Value const& value, bool* is_dead) {
return (uintx)value->hash();
}
static void* allocate_node(void* context, size_t size, Value const& value) {
ObjectMonitorTable::inc_items_count();
return AllocateHeap(size, mtObjectMonitor);
};
static void free_node(void* context, void* memory, Value const& value) {
ObjectMonitorTable::dec_items_count();
FreeHeap(memory);
}
};
using ConcurrentTable = ConcurrentHashTable<Config, mtObjectMonitor>;
static ConcurrentTable* _table;
static volatile size_t _items_count;
static size_t _table_size;
static volatile bool _resize;
class Lookup : public StackObj {
oop _obj;
public:
explicit Lookup(oop obj) : _obj(obj) {}
uintx get_hash() const {
uintx hash = _obj->mark().hash();
assert(hash != 0, "should have a hash");
return hash;
}
bool equals(ObjectMonitor** value) {
assert(*value != nullptr, "must be");
return (*value)->object_refers_to(_obj);
}
bool is_dead(ObjectMonitor** value) {
assert(*value != nullptr, "must be");
return false;
}
};
class LookupMonitor : public StackObj {
ObjectMonitor* _monitor;
public:
explicit LookupMonitor(ObjectMonitor* monitor) : _monitor(monitor) {}
uintx get_hash() const {
return _monitor->hash();
}
bool equals(ObjectMonitor** value) {
return (*value) == _monitor;
}
bool is_dead(ObjectMonitor** value) {
assert(*value != nullptr, "must be");
return (*value)->object_is_dead();
}
};
static void inc_items_count() {
AtomicAccess::inc(&_items_count, memory_order_relaxed);
}
static void dec_items_count() {
AtomicAccess::dec(&_items_count, memory_order_relaxed);
}
static double get_load_factor() {
size_t count = AtomicAccess::load(&_items_count);
return (double)count / (double)_table_size;
}
static size_t table_size(Thread* current = Thread::current()) {
return ((size_t)1) << _table->get_size_log2(current);
}
static size_t max_log_size() {
// TODO[OMTable]: Evaluate the max size.
// TODO[OMTable]: Need to fix init order to use Universe::heap()->max_capacity();
// Using MaxHeapSize directly this early may be wrong, and there
// are definitely rounding errors (alignment).
const size_t max_capacity = MaxHeapSize;
const size_t min_object_size = CollectedHeap::min_dummy_object_size() * HeapWordSize;
const size_t max_objects = max_capacity / MAX2(MinObjAlignmentInBytes, checked_cast<int>(min_object_size));
const size_t log_max_objects = log2i_graceful(max_objects);
return MAX2(MIN2<size_t>(SIZE_BIG_LOG2, log_max_objects), min_log_size());
}
static size_t min_log_size() {
// ~= log(AvgMonitorsPerThreadEstimate default)
return 10;
}
template<typename V>
static size_t clamp_log_size(V log_size) {
return MAX2(MIN2(log_size, checked_cast<V>(max_log_size())), checked_cast<V>(min_log_size()));
}
static size_t initial_log_size() {
const size_t estimate = log2i(MAX2(os::processor_count(), 1)) + log2i(MAX2(AvgMonitorsPerThreadEstimate, size_t(1)));
return clamp_log_size(estimate);
}
static size_t grow_hint () {
return ConcurrentTable::DEFAULT_GROW_HINT;
}
public:
static void create() {
_table = new ConcurrentTable(initial_log_size(), max_log_size(), grow_hint());
_items_count = 0;
_table_size = table_size();
_resize = false;
}
static void verify_monitor_get_result(oop obj, ObjectMonitor* monitor) {
#ifdef ASSERT
if (SafepointSynchronize::is_at_safepoint()) {
bool has_monitor = obj->mark().has_monitor();
assert(has_monitor == (monitor != nullptr),
"Inconsistency between markWord and ObjectMonitorTable has_monitor: %s monitor: " PTR_FORMAT,
BOOL_TO_STR(has_monitor), p2i(monitor));
}
#endif
}
static ObjectMonitor* monitor_get(Thread* current, oop obj) {
ObjectMonitor* result = nullptr;
Lookup lookup_f(obj);
auto found_f = [&](ObjectMonitor** found) {
assert((*found)->object_peek() == obj, "must be");
result = *found;
};
_table->get(current, lookup_f, found_f);
verify_monitor_get_result(obj, result);
return result;
}
static void try_notify_grow() {
if (!_table->is_max_size_reached() && !AtomicAccess::load(&_resize)) {
AtomicAccess::store(&_resize, true);
if (Service_lock->try_lock()) {
Service_lock->notify();
Service_lock->unlock();
}
}
}
static bool should_shrink() {
// Not implemented;
return false;
}
static constexpr double GROW_LOAD_FACTOR = 0.75;
static bool should_grow() {
return get_load_factor() > GROW_LOAD_FACTOR && !_table->is_max_size_reached();
}
static bool should_resize() {
return should_grow() || should_shrink() || AtomicAccess::load(&_resize);
}
template<typename Task, typename... Args>
static bool run_task(JavaThread* current, Task& task, const char* task_name, Args&... args) {
if (task.prepare(current)) {
log_trace(monitortable)("Started to %s", task_name);
TraceTime timer(task_name, TRACETIME_LOG(Debug, monitortable, perf));
while (task.do_task(current, args...)) {
task.pause(current);
{
ThreadBlockInVM tbivm(current);
}
task.cont(current);
}
task.done(current);
return true;
}
return false;
}
static bool grow(JavaThread* current) {
ConcurrentTable::GrowTask grow_task(_table);
if (run_task(current, grow_task, "Grow")) {
_table_size = table_size(current);
log_info(monitortable)("Grown to size: %zu", _table_size);
return true;
}
return false;
}
static bool clean(JavaThread* current) {
ConcurrentTable::BulkDeleteTask clean_task(_table);
auto is_dead = [&](ObjectMonitor** monitor) {
return (*monitor)->object_is_dead();
};
auto do_nothing = [&](ObjectMonitor** monitor) {};
NativeHeapTrimmer::SuspendMark sm("ObjectMonitorTable");
return run_task(current, clean_task, "Clean", is_dead, do_nothing);
}
static bool resize(JavaThread* current) {
LogTarget(Info, monitortable) lt;
bool success = false;
if (should_grow()) {
lt.print("Start growing with load factor %f", get_load_factor());
success = grow(current);
} else {
if (!_table->is_max_size_reached() && AtomicAccess::load(&_resize)) {
lt.print("WARNING: Getting resize hints with load factor %f", get_load_factor());
}
lt.print("Start cleaning with load factor %f", get_load_factor());
success = clean(current);
}
AtomicAccess::store(&_resize, false);
return success;
}
static ObjectMonitor* monitor_put_get(Thread* current, ObjectMonitor* monitor, oop obj) {
// Enter the monitor into the concurrent hashtable.
ObjectMonitor* result = monitor;
Lookup lookup_f(obj);
auto found_f = [&](ObjectMonitor** found) {
assert((*found)->object_peek() == obj, "must be");
result = *found;
};
bool grow;
_table->insert_get(current, lookup_f, monitor, found_f, &grow);
verify_monitor_get_result(obj, result);
if (grow) {
try_notify_grow();
}
return result;
}
static bool remove_monitor_entry(Thread* current, ObjectMonitor* monitor) {
LookupMonitor lookup_f(monitor);
return _table->remove(current, lookup_f);
}
static bool contains_monitor(Thread* current, ObjectMonitor* monitor) {
LookupMonitor lookup_f(monitor);
bool result = false;
auto found_f = [&](ObjectMonitor** found) {
result = true;
};
_table->get(current, lookup_f, found_f);
return result;
}
static void print_on(outputStream* st) {
auto printer = [&] (ObjectMonitor** entry) {
ObjectMonitor* om = *entry;
oop obj = om->object_peek();
st->print("monitor=" PTR_FORMAT ", ", p2i(om));
st->print("object=" PTR_FORMAT, p2i(obj));
assert(obj->mark().hash() == om->hash(), "hash must match");
st->cr();
return true;
};
if (SafepointSynchronize::is_at_safepoint()) {
_table->do_safepoint_scan(printer);
} else {
_table->do_scan(Thread::current(), printer);
}
}
};
ObjectMonitorTable::ConcurrentTable* ObjectMonitorTable::_table = nullptr;
volatile size_t ObjectMonitorTable::_items_count = 0;
size_t ObjectMonitorTable::_table_size = 0;
volatile bool ObjectMonitorTable::_resize = false;
ObjectMonitor* ObjectSynchronizer::get_or_insert_monitor_from_table(oop object, JavaThread* current, bool* inserted) {
ObjectMonitor* monitor = get_monitor_from_table(current, object);
if (monitor != nullptr) {