src/share/vm/services/lowMemoryDetector.hpp - platform/external/jetbrains/jdk8u_hotspot - Git at Google

 /*
  * Copyright (c) 2003, 2012, 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_VM_SERVICES_LOWMEMORYDETECTOR_HPP
 #define SHARE_VM_SERVICES_LOWMEMORYDETECTOR_HPP

 #include "memory/allocation.hpp"
 #include "services/memoryPool.hpp"
 #include "services/memoryService.hpp"

 // Low Memory Detection Support
 // Two memory alarms in the JDK (we called them sensors).
 //   - Heap memory sensor
 //   - Non-heap memory sensor
 // When the VM detects if the memory usage of a memory pool has reached
 // or exceeded its threshold, it will trigger the sensor for the type
 // of the memory pool (heap or nonheap or both).
 //
 // If threshold == -1, no low memory detection is supported and
 // the threshold value is not allowed to be changed.
 // If threshold == 0, no low memory detection is performed for
 // that memory pool.  The threshold can be set to any non-negative
 // value.
 //
 // The default threshold of the Hotspot memory pools are:
 //   Eden space        -1
 //   Survivor space 1  -1
 //   Survivor space 2  -1
 //   Old generation    0
 //   Perm generation   0
 //   CodeCache         0
 //
 // For heap memory, detection will be performed when GC finishes
 // and also in the slow path allocation.
 // For Code cache, detection will be performed in the allocation
 // and deallocation.
 //
 // May need to deal with hysteresis effect.
 //
 // Memory detection code runs in the Service thread (serviceThread.hpp).

 class OopClosure;
 class MemoryPool;

 class ThresholdSupport : public CHeapObj<mtInternal> {
  private:
   bool            _support_high_threshold;
   bool            _support_low_threshold;
   size_t          _high_threshold;
   size_t          _low_threshold;
  public:
   ThresholdSupport(bool support_high, bool support_low) {
     _support_high_threshold = support_high;
     _support_low_threshold = support_low;
     _high_threshold = 0;
     _low_threshold= 0;
   }

   size_t      high_threshold() const        { return _high_threshold; }
   size_t      low_threshold()  const        { return _low_threshold; }
   bool        is_high_threshold_supported() { return _support_high_threshold; }
   bool        is_low_threshold_supported()  { return _support_low_threshold; }

   bool        is_high_threshold_crossed(MemoryUsage usage) {
     if (_support_high_threshold && _high_threshold > 0) {
       return (usage.used() >= _high_threshold);
     }
     return false;
   }
   bool        is_low_threshold_crossed(MemoryUsage usage) {
     if (_support_low_threshold && _low_threshold > 0) {
       return (usage.used() < _low_threshold);
     }
     return false;
   }

   size_t      set_high_threshold(size_t new_threshold) {
     assert(_support_high_threshold, "can only be set if supported");
     assert(new_threshold >= _low_threshold, "new_threshold must be >= _low_threshold");
     size_t prev = _high_threshold;
     _high_threshold = new_threshold;
     return prev;
   }

   size_t      set_low_threshold(size_t new_threshold) {
     assert(_support_low_threshold, "can only be set if supported");
     assert(new_threshold <= _high_threshold, "new_threshold must be <= _high_threshold");
     size_t prev = _low_threshold;
     _low_threshold = new_threshold;
     return prev;
   }
 };

 class SensorInfo : public CHeapObj<mtInternal> {
 private:
   instanceOop     _sensor_obj;
   bool            _sensor_on;
   size_t          _sensor_count;

   // before the actual sensor on flag and sensor count are set
   // we maintain the number of pending triggers and clears.
   // _pending_trigger_count means the number of pending triggers
   // and the sensor count should be incremented by the same number.

   int             _pending_trigger_count;

   // _pending_clear_count takes precedence if it's > 0 which
   // indicates the resulting sensor will be off
   // Sensor trigger requests will reset this clear count to
   // indicate the resulting flag should be on.

   int             _pending_clear_count;

   MemoryUsage     _usage;

   void clear(int count, TRAPS);
   void trigger(int count, TRAPS);
 public:
   SensorInfo();
   void set_sensor(instanceOop sensor) {
     assert(_sensor_obj == NULL, "Should be set only once");
     _sensor_obj = sensor;
   }

   bool has_pending_requests() {
     return (_pending_trigger_count > 0 || _pending_clear_count > 0);
   }

   int pending_trigger_count()      { return _pending_trigger_count; }
   int pending_clear_count()        { return _pending_clear_count; }

   // When this method is used, the memory usage is monitored
   // as a gauge attribute.  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 set_gauge_sensor_level(MemoryUsage usage, ThresholdSupport* high_low_threshold);

   // 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.
   //
   // 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 set_counter_sensor_level(MemoryUsage usage, ThresholdSupport* counter_threshold);

   void process_pending_requests(TRAPS);
   void oops_do(OopClosure* f);

 #ifndef PRODUCT
   // printing on default output stream;
   void print();
 #endif // PRODUCT
 };

 class LowMemoryDetector : public AllStatic {
   friend class LowMemoryDetectorDisabler;
   friend class ServiceThread;
 private:
   // true if any collected heap has low memory detection enabled
   static volatile bool _enabled_for_collected_pools;
   // > 0 if temporary disabed
   static volatile jint _disabled_count;

   static void check_memory_usage();
   static bool has_pending_requests();
   static bool temporary_disabled() { return _disabled_count > 0; }
   static void disable() { Atomic::inc(&_disabled_count); }
   static void enable() { Atomic::dec(&_disabled_count); }
   static void process_sensor_changes(TRAPS);

 public:
   static void detect_low_memory();
   static void detect_low_memory(MemoryPool* pool);
   static void detect_after_gc_memory(MemoryPool* pool);

   static bool is_enabled(MemoryPool* pool) {
     // low memory detection is enabled for collected memory pools
     // iff one of the collected memory pool has a sensor and the
     // threshold set non-zero
     if (pool->usage_sensor() == NULL) {
       return false;
     } else {
       ThresholdSupport* threshold_support = pool->usage_threshold();
       return (threshold_support->is_high_threshold_supported() ?
                (threshold_support->high_threshold() > 0) : false);
     }
   }

   // indicates if low memory detection is enabled for any collected
   // memory pools
   static inline bool is_enabled_for_collected_pools() {
     return !temporary_disabled() && _enabled_for_collected_pools;
   }

   // recompute enabled flag
   static void recompute_enabled_for_collected_pools();

   // low memory detection for collected memory pools.
   static inline void detect_low_memory_for_collected_pools() {
     // no-op if low memory detection not enabled
     if (!is_enabled_for_collected_pools()) {
       return;
     }
     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 low memory detection is enabled then check if the
       // current used exceeds the high threshold
       if (pool->is_collected_pool() && is_enabled(pool)) {
         size_t used = pool->used_in_bytes();
         size_t high = pool->usage_threshold()->high_threshold();
         if (used > high) {
           detect_low_memory(pool);
         }
       }
     }
   }
 };

 class LowMemoryDetectorDisabler: public StackObj {
 public:
   LowMemoryDetectorDisabler()
   {
     LowMemoryDetector::disable();
   }
   ~LowMemoryDetectorDisabler()
   {
     assert(LowMemoryDetector::temporary_disabled(), "should be disabled!");
     LowMemoryDetector::enable();
   }
 };

 #endif // SHARE_VM_SERVICES_LOWMEMORYDETECTOR_HPP
	/*
	* Copyright (c) 2003, 2012, 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_VM_SERVICES_LOWMEMORYDETECTOR_HPP
	#define SHARE_VM_SERVICES_LOWMEMORYDETECTOR_HPP

	#include "memory/allocation.hpp"
	#include "services/memoryPool.hpp"
	#include "services/memoryService.hpp"

	// Low Memory Detection Support
	// Two memory alarms in the JDK (we called them sensors).
	// - Heap memory sensor
	// - Non-heap memory sensor
	// When the VM detects if the memory usage of a memory pool has reached
	// or exceeded its threshold, it will trigger the sensor for the type
	// of the memory pool (heap or nonheap or both).
	//
	// If threshold == -1, no low memory detection is supported and
	// the threshold value is not allowed to be changed.
	// If threshold == 0, no low memory detection is performed for
	// that memory pool. The threshold can be set to any non-negative
	// value.
	//
	// The default threshold of the Hotspot memory pools are:
	// Eden space -1
	// Survivor space 1 -1
	// Survivor space 2 -1
	// Old generation 0
	// Perm generation 0
	// CodeCache 0
	//
	// For heap memory, detection will be performed when GC finishes
	// and also in the slow path allocation.
	// For Code cache, detection will be performed in the allocation
	// and deallocation.
	//
	// May need to deal with hysteresis effect.
	//
	// Memory detection code runs in the Service thread (serviceThread.hpp).

	class OopClosure;
	class MemoryPool;

	class ThresholdSupport : public CHeapObj<mtInternal> {
	private:
	bool _support_high_threshold;
	bool _support_low_threshold;
	size_t _high_threshold;
	size_t _low_threshold;
	public:
	ThresholdSupport(bool support_high, bool support_low) {
	_support_high_threshold = support_high;
	_support_low_threshold = support_low;
	_high_threshold = 0;
	_low_threshold= 0;
	}

	size_t high_threshold() const { return _high_threshold; }
	size_t low_threshold() const { return _low_threshold; }
	bool is_high_threshold_supported() { return _support_high_threshold; }
	bool is_low_threshold_supported() { return _support_low_threshold; }

	bool is_high_threshold_crossed(MemoryUsage usage) {
	if (_support_high_threshold && _high_threshold > 0) {
	return (usage.used() >= _high_threshold);
	}
	return false;
	}
	bool is_low_threshold_crossed(MemoryUsage usage) {
	if (_support_low_threshold && _low_threshold > 0) {
	return (usage.used() < _low_threshold);
	}
	return false;
	}

	size_t set_high_threshold(size_t new_threshold) {
	assert(_support_high_threshold, "can only be set if supported");
	assert(new_threshold >= _low_threshold, "new_threshold must be >= _low_threshold");
	size_t prev = _high_threshold;
	_high_threshold = new_threshold;
	return prev;
	}

	size_t set_low_threshold(size_t new_threshold) {
	assert(_support_low_threshold, "can only be set if supported");
	assert(new_threshold <= _high_threshold, "new_threshold must be <= _high_threshold");
	size_t prev = _low_threshold;
	_low_threshold = new_threshold;
	return prev;
	}
	};

	class SensorInfo : public CHeapObj<mtInternal> {
	private:
	instanceOop _sensor_obj;
	bool _sensor_on;
	size_t _sensor_count;

	// before the actual sensor on flag and sensor count are set
	// we maintain the number of pending triggers and clears.
	// _pending_trigger_count means the number of pending triggers
	// and the sensor count should be incremented by the same number.

	int _pending_trigger_count;

	// _pending_clear_count takes precedence if it's > 0 which
	// indicates the resulting sensor will be off
	// Sensor trigger requests will reset this clear count to
	// indicate the resulting flag should be on.

	int _pending_clear_count;

	MemoryUsage _usage;

	void clear(int count, TRAPS);
	void trigger(int count, TRAPS);
	public:
	SensorInfo();
	void set_sensor(instanceOop sensor) {
	assert(_sensor_obj == NULL, "Should be set only once");
	_sensor_obj = sensor;
	}

	bool has_pending_requests() {
	return (_pending_trigger_count > 0 \|\| _pending_clear_count > 0);
	}

	int pending_trigger_count() { return _pending_trigger_count; }
	int pending_clear_count() { return _pending_clear_count; }

	// When this method is used, the memory usage is monitored
	// as a gauge attribute. 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 set_gauge_sensor_level(MemoryUsage usage, ThresholdSupport* high_low_threshold);

	// 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.
	//
	// 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 set_counter_sensor_level(MemoryUsage usage, ThresholdSupport* counter_threshold);

	void process_pending_requests(TRAPS);
	void oops_do(OopClosure* f);

	#ifndef PRODUCT
	// printing on default output stream;
	void print();
	#endif // PRODUCT
	};

	class LowMemoryDetector : public AllStatic {
	friend class LowMemoryDetectorDisabler;
	friend class ServiceThread;
	private:
	// true if any collected heap has low memory detection enabled
	static volatile bool _enabled_for_collected_pools;
	// > 0 if temporary disabed
	static volatile jint _disabled_count;

	static void check_memory_usage();
	static bool has_pending_requests();
	static bool temporary_disabled() { return _disabled_count > 0; }
	static void disable() { Atomic::inc(&_disabled_count); }
	static void enable() { Atomic::dec(&_disabled_count); }
	static void process_sensor_changes(TRAPS);

	public:
	static void detect_low_memory();
	static void detect_low_memory(MemoryPool* pool);
	static void detect_after_gc_memory(MemoryPool* pool);

	static bool is_enabled(MemoryPool* pool) {
	// low memory detection is enabled for collected memory pools
	// iff one of the collected memory pool has a sensor and the
	// threshold set non-zero
	if (pool->usage_sensor() == NULL) {
	return false;
	} else {
	ThresholdSupport* threshold_support = pool->usage_threshold();
	return (threshold_support->is_high_threshold_supported() ?
	(threshold_support->high_threshold() > 0) : false);
	}
	}

	// indicates if low memory detection is enabled for any collected
	// memory pools
	static inline bool is_enabled_for_collected_pools() {
	return !temporary_disabled() && _enabled_for_collected_pools;
	}

	// recompute enabled flag
	static void recompute_enabled_for_collected_pools();

	// low memory detection for collected memory pools.
	static inline void detect_low_memory_for_collected_pools() {
	// no-op if low memory detection not enabled
	if (!is_enabled_for_collected_pools()) {
	return;
	}
	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 low memory detection is enabled then check if the
	// current used exceeds the high threshold
	if (pool->is_collected_pool() && is_enabled(pool)) {
	size_t used = pool->used_in_bytes();
	size_t high = pool->usage_threshold()->high_threshold();
	if (used > high) {
	detect_low_memory(pool);
	}
	}
	}
	}
	};

	class LowMemoryDetectorDisabler: public StackObj {
	public:
	LowMemoryDetectorDisabler()
	{
	LowMemoryDetector::disable();
	}
	~LowMemoryDetectorDisabler()
	{
	assert(LowMemoryDetector::temporary_disabled(), "should be disabled!");
	LowMemoryDetector::enable();
	}
	};

	#endif // SHARE_VM_SERVICES_LOWMEMORYDETECTOR_HPP