duke@435: /*
drchase@6680:  * Copyright (c) 2003, 2014, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
stefank@2314: #include "precompiled.hpp"
stefank@2314: #include "classfile/systemDictionary.hpp"
stefank@2314: #include "classfile/vmSymbols.hpp"
stefank@2314: #include "oops/oop.inline.hpp"
stefank@2314: #include "runtime/interfaceSupport.hpp"
stefank@2314: #include "runtime/java.hpp"
stefank@2314: #include "runtime/javaCalls.hpp"
stefank@2314: #include "runtime/mutex.hpp"
stefank@2314: #include "runtime/mutexLocker.hpp"
stefank@2314: #include "services/lowMemoryDetector.hpp"
stefank@2314: #include "services/management.hpp"
duke@435: 
duke@435: volatile bool LowMemoryDetector::_enabled_for_collected_pools = false;
duke@435: volatile jint LowMemoryDetector::_disabled_count = 0;
duke@435: 
duke@435: bool LowMemoryDetector::has_pending_requests() {
kamg@2511:   assert(Service_lock->owned_by_self(), "Must own Service_lock");
duke@435:   bool has_requests = false;
duke@435:   int num_memory_pools = MemoryService::num_memory_pools();
duke@435:   for (int i = 0; i < num_memory_pools; i++) {
duke@435:     MemoryPool* pool = MemoryService::get_memory_pool(i);
duke@435:     SensorInfo* sensor = pool->usage_sensor();
duke@435:     if (sensor != NULL) {
duke@435:       has_requests = has_requests || sensor->has_pending_requests();
duke@435:     }
duke@435: 
duke@435:     SensorInfo* gc_sensor = pool->gc_usage_sensor();
duke@435:     if (gc_sensor != NULL) {
duke@435:       has_requests = has_requests || gc_sensor->has_pending_requests();
duke@435:     }
duke@435:   }
duke@435:   return has_requests;
duke@435: }
duke@435: 
kamg@2511: void LowMemoryDetector::process_sensor_changes(TRAPS) {
kamg@2511:   ResourceMark rm(THREAD);
kamg@2511:   HandleMark hm(THREAD);
duke@435: 
kamg@2511:   // No need to hold Service_lock to call out to Java
kamg@2511:   int num_memory_pools = MemoryService::num_memory_pools();
kamg@2511:   for (int i = 0; i < num_memory_pools; i++) {
kamg@2511:     MemoryPool* pool = MemoryService::get_memory_pool(i);
kamg@2511:     SensorInfo* sensor = pool->usage_sensor();
kamg@2511:     SensorInfo* gc_sensor = pool->gc_usage_sensor();
kamg@2511:     if (sensor != NULL && sensor->has_pending_requests()) {
kamg@2511:       sensor->process_pending_requests(CHECK);
duke@435:     }
kamg@2511:     if (gc_sensor != NULL && gc_sensor->has_pending_requests()) {
kamg@2511:       gc_sensor->process_pending_requests(CHECK);
duke@435:     }
duke@435:   }
duke@435: }
duke@435: 
duke@435: // This method could be called from any Java threads
duke@435: // and also VMThread.
duke@435: void LowMemoryDetector::detect_low_memory() {
kamg@2511:   MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
duke@435: 
duke@435:   bool has_pending_requests = false;
duke@435:   int num_memory_pools = MemoryService::num_memory_pools();
duke@435:   for (int i = 0; i < num_memory_pools; i++) {
duke@435:     MemoryPool* pool = MemoryService::get_memory_pool(i);
duke@435:     SensorInfo* sensor = pool->usage_sensor();
duke@435:     if (sensor != NULL &&
duke@435:         pool->usage_threshold()->is_high_threshold_supported() &&
duke@435:         pool->usage_threshold()->high_threshold() != 0) {
duke@435:       MemoryUsage usage = pool->get_memory_usage();
duke@435:       sensor->set_gauge_sensor_level(usage,
duke@435:                                      pool->usage_threshold());
duke@435:       has_pending_requests = has_pending_requests || sensor->has_pending_requests();
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   if (has_pending_requests) {
kamg@2511:     Service_lock->notify_all();
duke@435:   }
duke@435: }
duke@435: 
duke@435: // This method could be called from any Java threads
duke@435: // and also VMThread.
duke@435: void LowMemoryDetector::detect_low_memory(MemoryPool* pool) {
duke@435:   SensorInfo* sensor = pool->usage_sensor();
duke@435:   if (sensor == NULL ||
duke@435:       !pool->usage_threshold()->is_high_threshold_supported() ||
duke@435:       pool->usage_threshold()->high_threshold() == 0) {
duke@435:     return;
duke@435:   }
duke@435: 
duke@435:   {
kamg@2511:     MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
duke@435: 
duke@435:     MemoryUsage usage = pool->get_memory_usage();
duke@435:     sensor->set_gauge_sensor_level(usage,
duke@435:                                    pool->usage_threshold());
duke@435:     if (sensor->has_pending_requests()) {
duke@435:       // notify sensor state update
kamg@2511:       Service_lock->notify_all();
duke@435:     }
duke@435:   }
duke@435: }
duke@435: 
duke@435: // Only called by VMThread at GC time
duke@435: void LowMemoryDetector::detect_after_gc_memory(MemoryPool* pool) {
duke@435:   SensorInfo* sensor = pool->gc_usage_sensor();
duke@435:   if (sensor == NULL ||
duke@435:       !pool->gc_usage_threshold()->is_high_threshold_supported() ||
duke@435:       pool->gc_usage_threshold()->high_threshold() == 0) {
duke@435:     return;
duke@435:   }
duke@435: 
duke@435:   {
kamg@2511:     MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
duke@435: 
duke@435:     MemoryUsage usage = pool->get_last_collection_usage();
duke@435:     sensor->set_counter_sensor_level(usage, pool->gc_usage_threshold());
duke@435: 
duke@435:     if (sensor->has_pending_requests()) {
duke@435:       // notify sensor state update
kamg@2511:       Service_lock->notify_all();
duke@435:     }
duke@435:   }
duke@435: }
duke@435: 
duke@435: // recompute enabled flag
duke@435: void LowMemoryDetector::recompute_enabled_for_collected_pools() {
duke@435:   bool enabled = false;
duke@435:   int num_memory_pools = MemoryService::num_memory_pools();
duke@435:   for (int i=0; i<num_memory_pools; i++) {
duke@435:     MemoryPool* pool = MemoryService::get_memory_pool(i);
duke@435:     if (pool->is_collected_pool() && is_enabled(pool)) {
duke@435:       enabled = true;
duke@435:       break;
duke@435:     }
duke@435:   }
duke@435:   _enabled_for_collected_pools = enabled;
duke@435: }
duke@435: 
duke@435: SensorInfo::SensorInfo() {
duke@435:   _sensor_obj = NULL;
duke@435:   _sensor_on = false;
duke@435:   _sensor_count = 0;
duke@435:   _pending_trigger_count = 0;
duke@435:   _pending_clear_count = 0;
duke@435: }
duke@435: 
duke@435: // When this method is used, the memory usage is monitored
duke@435: // as a gauge attribute.  Sensor notifications (trigger or
duke@435: // clear) is only emitted at the first time it crosses
duke@435: // a threshold.
duke@435: //
duke@435: // High and low thresholds are designed to provide a
duke@435: // hysteresis mechanism to avoid repeated triggering
duke@435: // of notifications when the attribute value makes small oscillations
duke@435: // around the high or low threshold value.
duke@435: //
duke@435: // The sensor will be triggered if:
duke@435: //  (1) the usage is crossing above the high threshold and
duke@435: //      the sensor is currently off and no pending
duke@435: //      trigger requests; or
duke@435: //  (2) the usage is crossing above the high threshold and
duke@435: //      the sensor will be off (i.e. sensor is currently on
duke@435: //      and has pending clear requests).
duke@435: //
duke@435: // Subsequent crossings of the high threshold value do not cause
duke@435: // any triggers unless the usage becomes less than the low threshold.
duke@435: //
duke@435: // The sensor will be cleared if:
duke@435: //  (1) the usage is crossing below the low threshold and
duke@435: //      the sensor is currently on and no pending
duke@435: //      clear requests; or
duke@435: //  (2) the usage is crossing below the low threshold and
duke@435: //      the sensor will be on (i.e. sensor is currently off
duke@435: //      and has pending trigger requests).
duke@435: //
duke@435: // Subsequent crossings of the low threshold value do not cause
duke@435: // any clears unless the usage becomes greater than or equal
duke@435: // to the high threshold.
duke@435: //
duke@435: // If the current level is between high and low threhsold, no change.
duke@435: //
duke@435: void SensorInfo::set_gauge_sensor_level(MemoryUsage usage, ThresholdSupport* high_low_threshold) {
duke@435:   assert(high_low_threshold->is_high_threshold_supported(), "just checking");
duke@435: 
duke@435:   bool is_over_high = high_low_threshold->is_high_threshold_crossed(usage);
duke@435:   bool is_below_low = high_low_threshold->is_low_threshold_crossed(usage);
duke@435: 
duke@435:   assert(!(is_over_high && is_below_low), "Can't be both true");
duke@435: 
duke@435:   if (is_over_high &&
duke@435:         ((!_sensor_on && _pending_trigger_count == 0) ||
duke@435:          _pending_clear_count > 0)) {
duke@435:     // low memory detected and need to increment the trigger pending count
duke@435:     // if the sensor is off or will be off due to _pending_clear_ > 0
duke@435:     // Request to trigger the sensor
duke@435:     _pending_trigger_count++;
duke@435:     _usage = usage;
duke@435: 
duke@435:     if (_pending_clear_count > 0) {
duke@435:       // non-zero pending clear requests indicates that there are
duke@435:       // pending requests to clear this sensor.
duke@435:       // This trigger request needs to clear this clear count
duke@435:       // since the resulting sensor flag should be on.
duke@435:       _pending_clear_count = 0;
duke@435:     }
duke@435:   } else if (is_below_low &&
duke@435:                ((_sensor_on && _pending_clear_count == 0) ||
duke@435:                 (_pending_trigger_count > 0 && _pending_clear_count == 0))) {
duke@435:     // memory usage returns below the threshold
duke@435:     // Request to clear the sensor if the sensor is on or will be on due to
duke@435:     // _pending_trigger_count > 0 and also no clear request
duke@435:     _pending_clear_count++;
duke@435:   }
duke@435: }
duke@435: 
duke@435: // When this method is used, the memory usage is monitored as a
duke@435: // simple counter attribute.  The sensor will be triggered
duke@435: // whenever the usage is crossing the threshold to keep track
duke@435: // of the number of times the VM detects such a condition occurs.
duke@435: //
duke@435: // High and low thresholds are designed to provide a
duke@435: // hysteresis mechanism to avoid repeated triggering
duke@435: // of notifications when the attribute value makes small oscillations
duke@435: // around the high or low threshold value.
duke@435: //
duke@435: // The sensor will be triggered if:
duke@435: //   - the usage is crossing above the high threshold regardless
duke@435: //     of the current sensor state.
duke@435: //
duke@435: // The sensor will be cleared if:
duke@435: //  (1) the usage is crossing below the low threshold and
duke@435: //      the sensor is currently on; or
duke@435: //  (2) the usage is crossing below the low threshold and
duke@435: //      the sensor will be on (i.e. sensor is currently off
duke@435: //      and has pending trigger requests).
duke@435: void SensorInfo::set_counter_sensor_level(MemoryUsage usage, ThresholdSupport* counter_threshold) {
duke@435:   assert(counter_threshold->is_high_threshold_supported(), "just checking");
duke@435: 
duke@435:   bool is_over_high = counter_threshold->is_high_threshold_crossed(usage);
duke@435:   bool is_below_low = counter_threshold->is_low_threshold_crossed(usage);
duke@435: 
duke@435:   assert(!(is_over_high && is_below_low), "Can't be both true");
duke@435: 
duke@435:   if (is_over_high) {
duke@435:     _pending_trigger_count++;
duke@435:     _usage = usage;
duke@435:     _pending_clear_count = 0;
duke@435:   } else if (is_below_low && (_sensor_on || _pending_trigger_count > 0)) {
duke@435:     _pending_clear_count++;
duke@435:   }
duke@435: }
duke@435: 
duke@435: void SensorInfo::oops_do(OopClosure* f) {
duke@435:   f->do_oop((oop*) &_sensor_obj);
duke@435: }
duke@435: 
duke@435: void SensorInfo::process_pending_requests(TRAPS) {
duke@435:   if (!has_pending_requests()) {
duke@435:     return;
duke@435:   }
duke@435: 
duke@435:   int pending_count = pending_trigger_count();
duke@435:   if (pending_clear_count() > 0) {
duke@435:     clear(pending_count, CHECK);
duke@435:   } else {
duke@435:     trigger(pending_count, CHECK);
duke@435:   }
duke@435: 
duke@435: }
duke@435: 
duke@435: void SensorInfo::trigger(int count, TRAPS) {
duke@435:   assert(count <= _pending_trigger_count, "just checking");
duke@435: 
duke@435:   if (_sensor_obj != NULL) {
coleenp@4037:     Klass* k = Management::sun_management_Sensor_klass(CHECK);
duke@435:     instanceKlassHandle sensorKlass (THREAD, k);
duke@435:     Handle sensor_h(THREAD, _sensor_obj);
duke@435:     Handle usage_h = MemoryService::create_MemoryUsage_obj(_usage, CHECK);
duke@435: 
duke@435:     JavaValue result(T_VOID);
duke@435:     JavaCallArguments args(sensor_h);
duke@435:     args.push_int((int) count);
duke@435:     args.push_oop(usage_h);
duke@435: 
duke@435:     JavaCalls::call_virtual(&result,
duke@435:                             sensorKlass,
coleenp@2497:                             vmSymbols::trigger_name(),
coleenp@2497:                             vmSymbols::trigger_method_signature(),
duke@435:                             &args,
duke@435:                             CHECK);
duke@435:   }
duke@435: 
duke@435:   {
kamg@2511:     // Holds Service_lock and update the sensor state
kamg@2511:     MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
duke@435:     _sensor_on = true;
duke@435:     _sensor_count += count;
duke@435:     _pending_trigger_count = _pending_trigger_count - count;
duke@435:   }
duke@435: }
duke@435: 
duke@435: void SensorInfo::clear(int count, TRAPS) {
duke@435:   if (_sensor_obj != NULL) {
coleenp@4037:     Klass* k = Management::sun_management_Sensor_klass(CHECK);
duke@435:     instanceKlassHandle sensorKlass (THREAD, k);
duke@435:     Handle sensor(THREAD, _sensor_obj);
duke@435: 
duke@435:     JavaValue result(T_VOID);
duke@435:     JavaCallArguments args(sensor);
duke@435:     args.push_int((int) count);
duke@435:     JavaCalls::call_virtual(&result,
duke@435:                             sensorKlass,
coleenp@2497:                             vmSymbols::clear_name(),
coleenp@2497:                             vmSymbols::int_void_signature(),
duke@435:                             &args,
duke@435:                             CHECK);
duke@435:   }
duke@435: 
duke@435:   {
kamg@2511:     // Holds Service_lock and update the sensor state
kamg@2511:     MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
duke@435:     _sensor_on = false;
duke@435:     _pending_clear_count = 0;
duke@435:     _pending_trigger_count = _pending_trigger_count - count;
duke@435:   }
duke@435: }
duke@435: 
duke@435: //--------------------------------------------------------------
duke@435: // Non-product code
duke@435: 
duke@435: #ifndef PRODUCT
duke@435: void SensorInfo::print() {
drchase@6680:   tty->print_cr("%s count = " SIZE_FORMAT " pending_triggers = %d pending_clears = %d",
duke@435:                 (_sensor_on ? "on" : "off"),
duke@435:                 _sensor_count, _pending_trigger_count, _pending_clear_count);
duke@435: }
duke@435: 
duke@435: #endif // PRODUCT