truffle: src/share/vm/services/lowMemoryDetector.cpp comparison

comparison src/share/vm/services/lowMemoryDetector.cpp @ 0:a61af66fc99e jdk7-b24

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author	duke
date	Sat, 01 Dec 2007 00:00:00 +0000
parents
children	4ce7240d622c

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--1:000000000000
+:a61af66fc99e
+/*
+* Copyright 2003-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+* CA 95054 USA or visit www.sun.com if you need additional information or
+* have any questions.
+*
+*/
+# include "incls/_precompiled.incl"
+# include "incls/_lowMemoryDetector.cpp.incl"
+LowMemoryDetectorThread* LowMemoryDetector::_detector_thread = NULL;
+volatile bool LowMemoryDetector::_enabled_for_collected_pools = false;
+volatile jint LowMemoryDetector::_disabled_count = 0;
+void LowMemoryDetector::initialize() {
+EXCEPTION_MARK;
+instanceKlassHandle klass (THREAD,  SystemDictionary::thread_klass());
+instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
+const char thread_name[] = "Low Memory Detector";
+Handle string = java_lang_String::create_from_str(thread_name, CHECK);
+// Initialize thread_oop to put it into the system threadGroup
+Handle thread_group (THREAD, Universe::system_thread_group());
+JavaValue result(T_VOID);
+JavaCalls::call_special(&result, thread_oop,
+klass,
+vmSymbolHandles::object_initializer_name(),
+vmSymbolHandles::threadgroup_string_void_signature(),
+thread_group,
+string,
+CHECK);
+{
+MutexLocker mu(Threads_lock);
+_detector_thread = new LowMemoryDetectorThread(&low_memory_detector_thread_entry);
+// At this point it may be possible that no osthread was created for the
+// JavaThread due to lack of memory. We would have to throw an exception
+// in that case. However, since this must work and we do not allow
+// exceptions anyway, check and abort if this fails.
+if (_detector_thread == NULL || _detector_thread->osthread() == NULL) {
+vm_exit_during_initialization("java.lang.OutOfMemoryError",
+"unable to create new native thread");
+}
+java_lang_Thread::set_thread(thread_oop(), _detector_thread);
+java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
+java_lang_Thread::set_daemon(thread_oop());
+_detector_thread->set_threadObj(thread_oop());
+Threads::add(_detector_thread);
+Thread::start(_detector_thread);
+}
+}
+bool LowMemoryDetector::has_pending_requests() {
+assert(LowMemory_lock->owned_by_self(), "Must own LowMemory_lock");
+bool has_requests = false;
+int num_memory_pools = MemoryService::num_memory_pools();
+for (int i = 0; i < num_memory_pools; i++) {
+MemoryPool* pool = MemoryService::get_memory_pool(i);
+SensorInfo* sensor = pool->usage_sensor();
+if (sensor != NULL) {
+has_requests = has_requests || sensor->has_pending_requests();
+}
+SensorInfo* gc_sensor = pool->gc_usage_sensor();
+if (gc_sensor != NULL) {
+has_requests = has_requests || gc_sensor->has_pending_requests();
+}
+}
+return has_requests;
+}
+void LowMemoryDetector::low_memory_detector_thread_entry(JavaThread* jt, TRAPS) {
+while (true) {
+bool   sensors_changed = false;
+{
+// _no_safepoint_check_flag is used here as LowMemory_lock is a
+// special lock and the VMThread may acquire this lock at safepoint.
+// Need state transition ThreadBlockInVM so that this thread
+// will be handled by safepoint correctly when this thread is
+// notified at a safepoint.
+// This ThreadBlockInVM object is not also considered to be
+// suspend-equivalent because LowMemoryDetector threads are
+// not visible to external suspension.
+ThreadBlockInVM tbivm(jt);
+MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag);
+while (!(sensors_changed = has_pending_requests())) {
+// wait until one of the sensors has pending requests
+LowMemory_lock->wait(Mutex::_no_safepoint_check_flag);
+}
+}
+{
+ResourceMark rm(THREAD);
+HandleMark hm(THREAD);
+// No need to hold LowMemory_lock to call out to Java
+int num_memory_pools = MemoryService::num_memory_pools();
+for (int i = 0; i < num_memory_pools; i++) {
+MemoryPool* pool = MemoryService::get_memory_pool(i);
+SensorInfo* sensor = pool->usage_sensor();
+SensorInfo* gc_sensor = pool->gc_usage_sensor();
+if (sensor != NULL && sensor->has_pending_requests()) {
+sensor->process_pending_requests(CHECK);
+}
+if (gc_sensor != NULL && gc_sensor->has_pending_requests()) {
+gc_sensor->process_pending_requests(CHECK);
+}
+}
+}
+}
+}
+// This method could be called from any Java threads
+// and also VMThread.
+void LowMemoryDetector::detect_low_memory() {
+MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag);
+bool has_pending_requests = false;
+int num_memory_pools = MemoryService::num_memory_pools();
+for (int i = 0; i < num_memory_pools; i++) {
+MemoryPool* pool = MemoryService::get_memory_pool(i);
+SensorInfo* sensor = pool->usage_sensor();
+if (sensor != NULL &&
+pool->usage_threshold()->is_high_threshold_supported() &&
+pool->usage_threshold()->high_threshold() != 0) {
+MemoryUsage usage = pool->get_memory_usage();
+sensor->set_gauge_sensor_level(usage,
+pool->usage_threshold());
+has_pending_requests = has_pending_requests || sensor->has_pending_requests();
+}
+}
+if (has_pending_requests) {
+LowMemory_lock->notify_all();
+}
+}
+// This method could be called from any Java threads
+// and also VMThread.
+void LowMemoryDetector::detect_low_memory(MemoryPool* pool) {
+SensorInfo* sensor = pool->usage_sensor();
+if (sensor == NULL ||
+!pool->usage_threshold()->is_high_threshold_supported() ||
+pool->usage_threshold()->high_threshold() == 0) {
+return;
+}
+{
+MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag);
+MemoryUsage usage = pool->get_memory_usage();
+sensor->set_gauge_sensor_level(usage,
+pool->usage_threshold());
+if (sensor->has_pending_requests()) {
+// notify sensor state update
+LowMemory_lock->notify_all();
+}
+}
+}
+// Only called by VMThread at GC time
+void LowMemoryDetector::detect_after_gc_memory(MemoryPool* pool) {
+SensorInfo* sensor = pool->gc_usage_sensor();
+if (sensor == NULL ||
+!pool->gc_usage_threshold()->is_high_threshold_supported() ||
+pool->gc_usage_threshold()->high_threshold() == 0) {
+return;
+}
+{
+MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag);
+MemoryUsage usage = pool->get_last_collection_usage();
+sensor->set_counter_sensor_level(usage, pool->gc_usage_threshold());
+if (sensor->has_pending_requests()) {
+// notify sensor state update
+LowMemory_lock->notify_all();
+}
+}
+}
+// recompute enabled flag
+void LowMemoryDetector::recompute_enabled_for_collected_pools() {
+bool enabled = false;
+int num_memory_pools = MemoryService::num_memory_pools();
+for (int i=0; i<num_memory_pools; i++) {
+MemoryPool* pool = MemoryService::get_memory_pool(i);
+if (pool->is_collected_pool() && is_enabled(pool)) {
+enabled = true;
+break;
+}
+}
+_enabled_for_collected_pools = enabled;
+}
+SensorInfo::SensorInfo() {
+_sensor_obj = NULL;
+_sensor_on = false;
+_sensor_count = 0;
+_pending_trigger_count = 0;
+_pending_clear_count = 0;
+}
+// When this method is used, the memory usage is monitored
+// as a gauge attribute.  Sensor notifications (trigger or
+// clear) is only emitted at the first time it crosses
+// a threshold.
+//
+// High and low thresholds are designed to provide a
+// hysteresis mechanism to avoid repeated triggering
+// of notifications when the attribute value makes small oscillations
+// around the high or low threshold value.
+//
+// The sensor will be triggered if:
+//  (1) the usage is crossing above the high threshold and
+//      the sensor is currently off and no pending
+//      trigger requests; or
+//  (2) the usage is crossing above the high threshold and
+//      the sensor will be off (i.e. sensor is currently on
+//      and has pending clear requests).
+//
+// Subsequent crossings of the high threshold value do not cause
+// any triggers unless the usage becomes less than the low threshold.
+//
+// The sensor will be cleared if:
+//  (1) the usage is crossing below the low threshold and
+//      the sensor is currently on and no pending
+//      clear requests; or
+//  (2) the usage is crossing below the low threshold and
+//      the sensor will be on (i.e. sensor is currently off
+//      and has pending trigger requests).
+//
+// Subsequent crossings of the low threshold value do not cause
+// any clears unless the usage becomes greater than or equal
+// to the high threshold.
+//
+// If the current level is between high and low threhsold, no change.
+//
+void SensorInfo::set_gauge_sensor_level(MemoryUsage usage, ThresholdSupport* high_low_threshold) {
+assert(high_low_threshold->is_high_threshold_supported(), "just checking");
+bool is_over_high = high_low_threshold->is_high_threshold_crossed(usage);
+bool is_below_low = high_low_threshold->is_low_threshold_crossed(usage);
+assert(!(is_over_high && is_below_low), "Can't be both true");
+if (is_over_high &&
+((!_sensor_on && _pending_trigger_count == 0) ||
+_pending_clear_count > 0)) {
+// low memory detected and need to increment the trigger pending count
+// if the sensor is off or will be off due to _pending_clear_ > 0
+// Request to trigger the sensor
+_pending_trigger_count++;
+_usage = usage;
+if (_pending_clear_count > 0) {
+// non-zero pending clear requests indicates that there are
+// pending requests to clear this sensor.
+// This trigger request needs to clear this clear count
+// since the resulting sensor flag should be on.
+_pending_clear_count = 0;
+}
+} else if (is_below_low &&
+((_sensor_on && _pending_clear_count == 0) ||
+(_pending_trigger_count > 0 && _pending_clear_count == 0))) {
+// memory usage returns below the threshold
+// Request to clear the sensor if the sensor is on or will be on due to
+// _pending_trigger_count > 0 and also no clear request
+_pending_clear_count++;
+}
+}
+// When this method is used, the memory usage is monitored as a
+// simple counter attribute.  The sensor will be triggered
+// whenever the usage is crossing the threshold to keep track
+// of the number of times the VM detects such a condition occurs.
+//
+// High and low thresholds are designed to provide a
+// hysteresis mechanism to avoid repeated triggering
+// of notifications when the attribute value makes small oscillations
+// around the high or low threshold value.
+//
+// The sensor will be triggered if:
+//   - the usage is crossing above the high threshold regardless
+//     of the current sensor state.
+//
+// The sensor will be cleared if:
+//  (1) the usage is crossing below the low threshold and
+//      the sensor is currently on; or
+//  (2) the usage is crossing below the low threshold and
+//      the sensor will be on (i.e. sensor is currently off
+//      and has pending trigger requests).
+void SensorInfo::set_counter_sensor_level(MemoryUsage usage, ThresholdSupport* counter_threshold) {
+assert(counter_threshold->is_high_threshold_supported(), "just checking");
+bool is_over_high = counter_threshold->is_high_threshold_crossed(usage);
+bool is_below_low = counter_threshold->is_low_threshold_crossed(usage);
+assert(!(is_over_high && is_below_low), "Can't be both true");
+if (is_over_high) {
+_pending_trigger_count++;
+_usage = usage;
+_pending_clear_count = 0;
+} else if (is_below_low && (_sensor_on || _pending_trigger_count > 0)) {
+_pending_clear_count++;
+}
+}
+void SensorInfo::oops_do(OopClosure* f) {
+f->do_oop((oop*) &_sensor_obj);
+}
+void SensorInfo::process_pending_requests(TRAPS) {
+if (!has_pending_requests()) {
+return;
+}
+int pending_count = pending_trigger_count();
+if (pending_clear_count() > 0) {
+clear(pending_count, CHECK);
+} else {
+trigger(pending_count, CHECK);
+}
+}
+void SensorInfo::trigger(int count, TRAPS) {
+assert(count <= _pending_trigger_count, "just checking");
+if (_sensor_obj != NULL) {
+klassOop k = Management::sun_management_Sensor_klass(CHECK);
+instanceKlassHandle sensorKlass (THREAD, k);
+Handle sensor_h(THREAD, _sensor_obj);
+Handle usage_h = MemoryService::create_MemoryUsage_obj(_usage, CHECK);
+JavaValue result(T_VOID);
+JavaCallArguments args(sensor_h);
+args.push_int((int) count);
+args.push_oop(usage_h);
+JavaCalls::call_virtual(&result,
+sensorKlass,
+vmSymbolHandles::trigger_name(),
+vmSymbolHandles::trigger_method_signature(),
+&args,
+CHECK);
+}
+{
+// Holds LowMemory_lock and update the sensor state
+MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag);
+_sensor_on = true;
+_sensor_count += count;
+_pending_trigger_count = _pending_trigger_count - count;
+}
+}
+void SensorInfo::clear(int count, TRAPS) {
+if (_sensor_obj != NULL) {
+klassOop k = Management::sun_management_Sensor_klass(CHECK);
+instanceKlassHandle sensorKlass (THREAD, k);
+Handle sensor(THREAD, _sensor_obj);
+JavaValue result(T_VOID);
+JavaCallArguments args(sensor);
+args.push_int((int) count);
+JavaCalls::call_virtual(&result,
+sensorKlass,
+vmSymbolHandles::clear_name(),
+vmSymbolHandles::int_void_signature(),
+&args,
+CHECK);
+}
+{
+// Holds LowMemory_lock and update the sensor state
+MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag);
+_sensor_on = false;
+_pending_clear_count = 0;
+_pending_trigger_count = _pending_trigger_count - count;
+}
+}
+//--------------------------------------------------------------
+// Non-product code
+#ifndef PRODUCT
+void SensorInfo::print() {
+tty->print_cr("%s count = %ld pending_triggers = %ld pending_clears = %ld",
+(_sensor_on ? "on" : "off"),
+_sensor_count, _pending_trigger_count, _pending_clear_count);
+}
+#endif // PRODUCT

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comparison src/share/vm/services/lowMemoryDetector.cpp @ 0:a61af66fc99e jdk7-b24