1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/services/lowMemoryDetector.cpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,422 @@
1.4 +/*
1.5 + * Copyright 2003-2007 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +# include "incls/_precompiled.incl"
1.29 +# include "incls/_lowMemoryDetector.cpp.incl"
1.30 +
1.31 +LowMemoryDetectorThread* LowMemoryDetector::_detector_thread = NULL;
1.32 +volatile bool LowMemoryDetector::_enabled_for_collected_pools = false;
1.33 +volatile jint LowMemoryDetector::_disabled_count = 0;
1.34 +
1.35 +void LowMemoryDetector::initialize() {
1.36 + EXCEPTION_MARK;
1.37 +
1.38 + instanceKlassHandle klass (THREAD, SystemDictionary::thread_klass());
1.39 + instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1.40 +
1.41 + const char thread_name[] = "Low Memory Detector";
1.42 + Handle string = java_lang_String::create_from_str(thread_name, CHECK);
1.43 +
1.44 + // Initialize thread_oop to put it into the system threadGroup
1.45 + Handle thread_group (THREAD, Universe::system_thread_group());
1.46 + JavaValue result(T_VOID);
1.47 + JavaCalls::call_special(&result, thread_oop,
1.48 + klass,
1.49 + vmSymbolHandles::object_initializer_name(),
1.50 + vmSymbolHandles::threadgroup_string_void_signature(),
1.51 + thread_group,
1.52 + string,
1.53 + CHECK);
1.54 +
1.55 + {
1.56 + MutexLocker mu(Threads_lock);
1.57 + _detector_thread = new LowMemoryDetectorThread(&low_memory_detector_thread_entry);
1.58 +
1.59 + // At this point it may be possible that no osthread was created for the
1.60 + // JavaThread due to lack of memory. We would have to throw an exception
1.61 + // in that case. However, since this must work and we do not allow
1.62 + // exceptions anyway, check and abort if this fails.
1.63 + if (_detector_thread == NULL || _detector_thread->osthread() == NULL) {
1.64 + vm_exit_during_initialization("java.lang.OutOfMemoryError",
1.65 + "unable to create new native thread");
1.66 + }
1.67 +
1.68 + java_lang_Thread::set_thread(thread_oop(), _detector_thread);
1.69 + java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
1.70 + java_lang_Thread::set_daemon(thread_oop());
1.71 + _detector_thread->set_threadObj(thread_oop());
1.72 +
1.73 + Threads::add(_detector_thread);
1.74 + Thread::start(_detector_thread);
1.75 + }
1.76 +}
1.77 +
1.78 +bool LowMemoryDetector::has_pending_requests() {
1.79 + assert(LowMemory_lock->owned_by_self(), "Must own LowMemory_lock");
1.80 + bool has_requests = false;
1.81 + int num_memory_pools = MemoryService::num_memory_pools();
1.82 + for (int i = 0; i < num_memory_pools; i++) {
1.83 + MemoryPool* pool = MemoryService::get_memory_pool(i);
1.84 + SensorInfo* sensor = pool->usage_sensor();
1.85 + if (sensor != NULL) {
1.86 + has_requests = has_requests || sensor->has_pending_requests();
1.87 + }
1.88 +
1.89 + SensorInfo* gc_sensor = pool->gc_usage_sensor();
1.90 + if (gc_sensor != NULL) {
1.91 + has_requests = has_requests || gc_sensor->has_pending_requests();
1.92 + }
1.93 + }
1.94 + return has_requests;
1.95 +}
1.96 +
1.97 +void LowMemoryDetector::low_memory_detector_thread_entry(JavaThread* jt, TRAPS) {
1.98 + while (true) {
1.99 + bool sensors_changed = false;
1.100 +
1.101 + {
1.102 + // _no_safepoint_check_flag is used here as LowMemory_lock is a
1.103 + // special lock and the VMThread may acquire this lock at safepoint.
1.104 + // Need state transition ThreadBlockInVM so that this thread
1.105 + // will be handled by safepoint correctly when this thread is
1.106 + // notified at a safepoint.
1.107 +
1.108 + // This ThreadBlockInVM object is not also considered to be
1.109 + // suspend-equivalent because LowMemoryDetector threads are
1.110 + // not visible to external suspension.
1.111 +
1.112 + ThreadBlockInVM tbivm(jt);
1.113 +
1.114 + MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag);
1.115 + while (!(sensors_changed = has_pending_requests())) {
1.116 + // wait until one of the sensors has pending requests
1.117 + LowMemory_lock->wait(Mutex::_no_safepoint_check_flag);
1.118 + }
1.119 + }
1.120 +
1.121 + {
1.122 + ResourceMark rm(THREAD);
1.123 + HandleMark hm(THREAD);
1.124 +
1.125 + // No need to hold LowMemory_lock to call out to Java
1.126 + int num_memory_pools = MemoryService::num_memory_pools();
1.127 + for (int i = 0; i < num_memory_pools; i++) {
1.128 + MemoryPool* pool = MemoryService::get_memory_pool(i);
1.129 + SensorInfo* sensor = pool->usage_sensor();
1.130 + SensorInfo* gc_sensor = pool->gc_usage_sensor();
1.131 + if (sensor != NULL && sensor->has_pending_requests()) {
1.132 + sensor->process_pending_requests(CHECK);
1.133 + }
1.134 + if (gc_sensor != NULL && gc_sensor->has_pending_requests()) {
1.135 + gc_sensor->process_pending_requests(CHECK);
1.136 + }
1.137 + }
1.138 + }
1.139 + }
1.140 +}
1.141 +
1.142 +// This method could be called from any Java threads
1.143 +// and also VMThread.
1.144 +void LowMemoryDetector::detect_low_memory() {
1.145 + MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag);
1.146 +
1.147 + bool has_pending_requests = false;
1.148 + int num_memory_pools = MemoryService::num_memory_pools();
1.149 + for (int i = 0; i < num_memory_pools; i++) {
1.150 + MemoryPool* pool = MemoryService::get_memory_pool(i);
1.151 + SensorInfo* sensor = pool->usage_sensor();
1.152 + if (sensor != NULL &&
1.153 + pool->usage_threshold()->is_high_threshold_supported() &&
1.154 + pool->usage_threshold()->high_threshold() != 0) {
1.155 + MemoryUsage usage = pool->get_memory_usage();
1.156 + sensor->set_gauge_sensor_level(usage,
1.157 + pool->usage_threshold());
1.158 + has_pending_requests = has_pending_requests || sensor->has_pending_requests();
1.159 + }
1.160 + }
1.161 +
1.162 + if (has_pending_requests) {
1.163 + LowMemory_lock->notify_all();
1.164 + }
1.165 +}
1.166 +
1.167 +// This method could be called from any Java threads
1.168 +// and also VMThread.
1.169 +void LowMemoryDetector::detect_low_memory(MemoryPool* pool) {
1.170 + SensorInfo* sensor = pool->usage_sensor();
1.171 + if (sensor == NULL ||
1.172 + !pool->usage_threshold()->is_high_threshold_supported() ||
1.173 + pool->usage_threshold()->high_threshold() == 0) {
1.174 + return;
1.175 + }
1.176 +
1.177 + {
1.178 + MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag);
1.179 +
1.180 + MemoryUsage usage = pool->get_memory_usage();
1.181 + sensor->set_gauge_sensor_level(usage,
1.182 + pool->usage_threshold());
1.183 + if (sensor->has_pending_requests()) {
1.184 + // notify sensor state update
1.185 + LowMemory_lock->notify_all();
1.186 + }
1.187 + }
1.188 +}
1.189 +
1.190 +// Only called by VMThread at GC time
1.191 +void LowMemoryDetector::detect_after_gc_memory(MemoryPool* pool) {
1.192 + SensorInfo* sensor = pool->gc_usage_sensor();
1.193 + if (sensor == NULL ||
1.194 + !pool->gc_usage_threshold()->is_high_threshold_supported() ||
1.195 + pool->gc_usage_threshold()->high_threshold() == 0) {
1.196 + return;
1.197 + }
1.198 +
1.199 + {
1.200 + MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag);
1.201 +
1.202 + MemoryUsage usage = pool->get_last_collection_usage();
1.203 + sensor->set_counter_sensor_level(usage, pool->gc_usage_threshold());
1.204 +
1.205 + if (sensor->has_pending_requests()) {
1.206 + // notify sensor state update
1.207 + LowMemory_lock->notify_all();
1.208 + }
1.209 + }
1.210 +}
1.211 +
1.212 +// recompute enabled flag
1.213 +void LowMemoryDetector::recompute_enabled_for_collected_pools() {
1.214 + bool enabled = false;
1.215 + int num_memory_pools = MemoryService::num_memory_pools();
1.216 + for (int i=0; i<num_memory_pools; i++) {
1.217 + MemoryPool* pool = MemoryService::get_memory_pool(i);
1.218 + if (pool->is_collected_pool() && is_enabled(pool)) {
1.219 + enabled = true;
1.220 + break;
1.221 + }
1.222 + }
1.223 + _enabled_for_collected_pools = enabled;
1.224 +}
1.225 +
1.226 +SensorInfo::SensorInfo() {
1.227 + _sensor_obj = NULL;
1.228 + _sensor_on = false;
1.229 + _sensor_count = 0;
1.230 + _pending_trigger_count = 0;
1.231 + _pending_clear_count = 0;
1.232 +}
1.233 +
1.234 +// When this method is used, the memory usage is monitored
1.235 +// as a gauge attribute. Sensor notifications (trigger or
1.236 +// clear) is only emitted at the first time it crosses
1.237 +// a threshold.
1.238 +//
1.239 +// High and low thresholds are designed to provide a
1.240 +// hysteresis mechanism to avoid repeated triggering
1.241 +// of notifications when the attribute value makes small oscillations
1.242 +// around the high or low threshold value.
1.243 +//
1.244 +// The sensor will be triggered if:
1.245 +// (1) the usage is crossing above the high threshold and
1.246 +// the sensor is currently off and no pending
1.247 +// trigger requests; or
1.248 +// (2) the usage is crossing above the high threshold and
1.249 +// the sensor will be off (i.e. sensor is currently on
1.250 +// and has pending clear requests).
1.251 +//
1.252 +// Subsequent crossings of the high threshold value do not cause
1.253 +// any triggers unless the usage becomes less than the low threshold.
1.254 +//
1.255 +// The sensor will be cleared if:
1.256 +// (1) the usage is crossing below the low threshold and
1.257 +// the sensor is currently on and no pending
1.258 +// clear requests; or
1.259 +// (2) the usage is crossing below the low threshold and
1.260 +// the sensor will be on (i.e. sensor is currently off
1.261 +// and has pending trigger requests).
1.262 +//
1.263 +// Subsequent crossings of the low threshold value do not cause
1.264 +// any clears unless the usage becomes greater than or equal
1.265 +// to the high threshold.
1.266 +//
1.267 +// If the current level is between high and low threhsold, no change.
1.268 +//
1.269 +void SensorInfo::set_gauge_sensor_level(MemoryUsage usage, ThresholdSupport* high_low_threshold) {
1.270 + assert(high_low_threshold->is_high_threshold_supported(), "just checking");
1.271 +
1.272 + bool is_over_high = high_low_threshold->is_high_threshold_crossed(usage);
1.273 + bool is_below_low = high_low_threshold->is_low_threshold_crossed(usage);
1.274 +
1.275 + assert(!(is_over_high && is_below_low), "Can't be both true");
1.276 +
1.277 + if (is_over_high &&
1.278 + ((!_sensor_on && _pending_trigger_count == 0) ||
1.279 + _pending_clear_count > 0)) {
1.280 + // low memory detected and need to increment the trigger pending count
1.281 + // if the sensor is off or will be off due to _pending_clear_ > 0
1.282 + // Request to trigger the sensor
1.283 + _pending_trigger_count++;
1.284 + _usage = usage;
1.285 +
1.286 + if (_pending_clear_count > 0) {
1.287 + // non-zero pending clear requests indicates that there are
1.288 + // pending requests to clear this sensor.
1.289 + // This trigger request needs to clear this clear count
1.290 + // since the resulting sensor flag should be on.
1.291 + _pending_clear_count = 0;
1.292 + }
1.293 + } else if (is_below_low &&
1.294 + ((_sensor_on && _pending_clear_count == 0) ||
1.295 + (_pending_trigger_count > 0 && _pending_clear_count == 0))) {
1.296 + // memory usage returns below the threshold
1.297 + // Request to clear the sensor if the sensor is on or will be on due to
1.298 + // _pending_trigger_count > 0 and also no clear request
1.299 + _pending_clear_count++;
1.300 + }
1.301 +}
1.302 +
1.303 +// When this method is used, the memory usage is monitored as a
1.304 +// simple counter attribute. The sensor will be triggered
1.305 +// whenever the usage is crossing the threshold to keep track
1.306 +// of the number of times the VM detects such a condition occurs.
1.307 +//
1.308 +// High and low thresholds are designed to provide a
1.309 +// hysteresis mechanism to avoid repeated triggering
1.310 +// of notifications when the attribute value makes small oscillations
1.311 +// around the high or low threshold value.
1.312 +//
1.313 +// The sensor will be triggered if:
1.314 +// - the usage is crossing above the high threshold regardless
1.315 +// of the current sensor state.
1.316 +//
1.317 +// The sensor will be cleared if:
1.318 +// (1) the usage is crossing below the low threshold and
1.319 +// the sensor is currently on; or
1.320 +// (2) the usage is crossing below the low threshold and
1.321 +// the sensor will be on (i.e. sensor is currently off
1.322 +// and has pending trigger requests).
1.323 +void SensorInfo::set_counter_sensor_level(MemoryUsage usage, ThresholdSupport* counter_threshold) {
1.324 + assert(counter_threshold->is_high_threshold_supported(), "just checking");
1.325 +
1.326 + bool is_over_high = counter_threshold->is_high_threshold_crossed(usage);
1.327 + bool is_below_low = counter_threshold->is_low_threshold_crossed(usage);
1.328 +
1.329 + assert(!(is_over_high && is_below_low), "Can't be both true");
1.330 +
1.331 + if (is_over_high) {
1.332 + _pending_trigger_count++;
1.333 + _usage = usage;
1.334 + _pending_clear_count = 0;
1.335 + } else if (is_below_low && (_sensor_on || _pending_trigger_count > 0)) {
1.336 + _pending_clear_count++;
1.337 + }
1.338 +}
1.339 +
1.340 +void SensorInfo::oops_do(OopClosure* f) {
1.341 + f->do_oop((oop*) &_sensor_obj);
1.342 +}
1.343 +
1.344 +void SensorInfo::process_pending_requests(TRAPS) {
1.345 + if (!has_pending_requests()) {
1.346 + return;
1.347 + }
1.348 +
1.349 + int pending_count = pending_trigger_count();
1.350 + if (pending_clear_count() > 0) {
1.351 + clear(pending_count, CHECK);
1.352 + } else {
1.353 + trigger(pending_count, CHECK);
1.354 + }
1.355 +
1.356 +}
1.357 +
1.358 +void SensorInfo::trigger(int count, TRAPS) {
1.359 + assert(count <= _pending_trigger_count, "just checking");
1.360 +
1.361 + if (_sensor_obj != NULL) {
1.362 + klassOop k = Management::sun_management_Sensor_klass(CHECK);
1.363 + instanceKlassHandle sensorKlass (THREAD, k);
1.364 + Handle sensor_h(THREAD, _sensor_obj);
1.365 + Handle usage_h = MemoryService::create_MemoryUsage_obj(_usage, CHECK);
1.366 +
1.367 + JavaValue result(T_VOID);
1.368 + JavaCallArguments args(sensor_h);
1.369 + args.push_int((int) count);
1.370 + args.push_oop(usage_h);
1.371 +
1.372 + JavaCalls::call_virtual(&result,
1.373 + sensorKlass,
1.374 + vmSymbolHandles::trigger_name(),
1.375 + vmSymbolHandles::trigger_method_signature(),
1.376 + &args,
1.377 + CHECK);
1.378 + }
1.379 +
1.380 + {
1.381 + // Holds LowMemory_lock and update the sensor state
1.382 + MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag);
1.383 + _sensor_on = true;
1.384 + _sensor_count += count;
1.385 + _pending_trigger_count = _pending_trigger_count - count;
1.386 + }
1.387 +}
1.388 +
1.389 +void SensorInfo::clear(int count, TRAPS) {
1.390 + if (_sensor_obj != NULL) {
1.391 + klassOop k = Management::sun_management_Sensor_klass(CHECK);
1.392 + instanceKlassHandle sensorKlass (THREAD, k);
1.393 + Handle sensor(THREAD, _sensor_obj);
1.394 +
1.395 + JavaValue result(T_VOID);
1.396 + JavaCallArguments args(sensor);
1.397 + args.push_int((int) count);
1.398 + JavaCalls::call_virtual(&result,
1.399 + sensorKlass,
1.400 + vmSymbolHandles::clear_name(),
1.401 + vmSymbolHandles::int_void_signature(),
1.402 + &args,
1.403 + CHECK);
1.404 + }
1.405 +
1.406 + {
1.407 + // Holds LowMemory_lock and update the sensor state
1.408 + MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag);
1.409 + _sensor_on = false;
1.410 + _pending_clear_count = 0;
1.411 + _pending_trigger_count = _pending_trigger_count - count;
1.412 + }
1.413 +}
1.414 +
1.415 +//--------------------------------------------------------------
1.416 +// Non-product code
1.417 +
1.418 +#ifndef PRODUCT
1.419 +void SensorInfo::print() {
1.420 + tty->print_cr("%s count = %ld pending_triggers = %ld pending_clears = %ld",
1.421 + (_sensor_on ? "on" : "off"),
1.422 + _sensor_count, _pending_trigger_count, _pending_clear_count);
1.423 +}
1.424 +
1.425 +#endif // PRODUCT
