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+/*
+ * Copyright 2003-2006 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. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+
+package java.lang.management;
+
+/**
+ * The management interface for a memory pool. A memory pool
+ * represents the memory resource managed by the Java virtual machine
+ * and is managed by one or more {@link MemoryManagerMXBean memory managers}.
+ *
+ * <p> A Java virtual machine has one or more instances of the
+ * implementation class of this interface. An instance
+ * implementing this interface is
+ * an <a href="ManagementFactory.html#MXBean">MXBean</a>
+ * that can be obtained by calling
+ * the {@link ManagementFactory#getMemoryPoolMXBeans} method or
+ * from the {@link ManagementFactory#getPlatformMBeanServer
+ * platform <tt>MBeanServer</tt>} method.
+ *
+ * <p>The <tt>ObjectName</tt> for uniquely identifying the MXBean for
+ * a memory pool within an <tt>MBeanServer</tt> is:
+ * <blockquote>
+ * {@link ManagementFactory#MEMORY_POOL_MXBEAN_DOMAIN_TYPE
+ * <tt>java.lang:type=MemoryPool</tt>}<tt>,name=</tt><i>pool's name</i>
+ * </blockquote>
+ *
+ * <h4>Memory Type</h4>
+ * <p>The Java virtual machine has a heap for object allocation and also
+ * maintains non-heap memory for the method area and the Java virtual
+ * machine execution. The Java virtual machine can have one or more
+ * memory pools. Each memory pool represents a memory area
+ * of one of the following types:
+ * <ul>
+ * <li>{@link MemoryType#HEAP heap}</li>
+ * <li>{@link MemoryType#NON_HEAP non-heap}</li>
+ * </ul>
+ *
+ * <h4>Memory Usage Monitoring</h4>
+ *
+ * A memory pool has the following attributes:
+ * <ul>
+ * <li><a href="#Usage">Memory usage</a></li>
+ * <li><a href="#PeakUsage">Peak memory usage</a></li>
+ * <li><a href="#UsageThreshold">Usage Threshold</a></li>
+ * <li><a href="#CollectionThreshold">Collection Usage Threshold</a>
+ * (only supported by some <em>garbage-collected</em> memory pools)</li>
+ * </ul>
+ *
+ * <h4><a name="Usage">1. Memory Usage</a></h4>
+ *
+ * The {@link #getUsage} method provides an estimate
+ * of the current usage of a memory pool.
+ * For a garbage-collected memory pool, the amount of used memory
+ * includes the memory occupied by all objects in the pool
+ * including both <em>reachable</em> and <em>unreachable</em> objects.
+ *
+ * <p>In general, this method is a lightweight operation for getting
+ * an approximate memory usage. For some memory pools, for example,
+ * when objects are not packed contiguously, this method may be
+ * an expensive operation that requires some computation to determine
+ * the current memory usage. An implementation should document when
+ * this is the case.
+ *
+ * <h4><a name="PeakUsage">2. Peak Memory Usage</a></h4>
+ *
+ * The Java virtual machine maintains the peak memory usage of a memory
+ * pool since the virtual machine was started or the peak was reset.
+ * The peak memory usage is returned by the {@link #getPeakUsage} method
+ * and reset by calling the {@link #resetPeakUsage} method.
+ *
+ * <h4><a name="UsageThreshold">3. Usage Threshold</a></h4>
+ *
+ * Each memory pool has a manageable attribute
+ * called the <i>usage threshold</i> which has a default value supplied
+ * by the Java virtual machine. The default value is platform-dependent.
+ * The usage threshold can be set via the
+ * {@link #setUsageThreshold setUsageThreshold} method.
+ * If the threshold is set to a positive value, the usage threshold crossing
+ * checking is enabled in this memory pool.
+ * If the usage threshold is set to zero, usage
+ * threshold crossing checking on this memory pool is disabled.
+ * The {@link MemoryPoolMXBean#isUsageThresholdSupported} method can
+ * be used to determine if this functionality is supported.
+ * <p>
+ * A Java virtual machine performs usage threshold crossing checking on a
+ * memory pool basis at its best appropriate time, typically,
+ * at garbage collection time.
+ * Each memory pool maintains a {@link #getUsageThresholdCount
+ * usage threshold count} that will get incremented
+ * every time when the Java virtual machine
+ * detects that the memory pool usage is crossing the threshold.
+ * <p>
+ * This manageable usage threshold attribute is designed for monitoring the
+ * increasing trend of memory usage with low overhead.
+ * Usage threshold may not be appropriate for some memory pools.
+ * For example, a generational garbage collector, a common garbage collection
+ * algorithm used in many Java virtual machine implementations,
+ * manages two or more generations segregating objects by age.
+ * Most of the objects are allocated in
+ * the <em>youngest generation</em> (say a nursery memory pool).
+ * The nursery memory pool is designed to be filled up and
+ * collecting the nursery memory pool will free most of its memory space
+ * since it is expected to contain mostly short-lived objects
+ * and mostly are unreachable at garbage collection time.
+ * In this case, it is more appropriate for the nursery memory pool
+ * not to support a usage threshold. In addition,
+ * if the cost of an object allocation
+ * in one memory pool is very low (for example, just atomic pointer exchange),
+ * the Java virtual machine would probably not support the usage threshold
+ * for that memory pool since the overhead in comparing the usage with
+ * the threshold is higher than the cost of object allocation.
+ *
+ * <p>
+ * The memory usage of the system can be monitored using
+ * <a href="#Polling">polling</a> or
+ * <a href="#ThresholdNotification">threshold notification</a> mechanisms.
+ *
+ * <ol type="a">
+ * <li><a name="Polling"><b>Polling</b></a>
+ * <p>
+ * An application can continuously monitor its memory usage
+ * by calling either the {@link #getUsage} method for all
+ * memory pools or the {@link #isUsageThresholdExceeded} method
+ * for those memory pools that support a usage threshold.
+ * Below is example code that has a thread delicated for
+ * task distribution and processing. At every interval,
+ * it will determine if it should receive and process new tasks based
+ * on its memory usage. If the memory usage exceeds its usage threshold,
+ * it will redistribute all outstanding tasks to other VMs and
+ * stop receiving new tasks until the memory usage returns
+ * below its usage threshold.
+ *
+ * <pre>
+ * // Assume the usage threshold is supported for this pool.
+ * // Set the threshold to myThreshold above which no new tasks
+ * // should be taken.
+ * pool.setUsageThreshold(myThreshold);
+ * ....
+ *
+ * boolean lowMemory = false;
+ * while (true) {
+ * if (pool.isUsageThresholdExceeded()) {
+ * // potential low memory, so redistribute tasks to other VMs
+ * lowMemory = true;
+ * redistributeTasks();
+ * // stop receiving new tasks
+ * stopReceivingTasks();
+ * } else {
+ * if (lowMemory) {
+ * // resume receiving tasks
+ * lowMemory = false;
+ * resumeReceivingTasks();
+ * }
+ * // processing outstanding task
+ * ...
+ * }
+ * // sleep for sometime
+ * try {
+ * Thread.sleep(sometime);
+ * } catch (InterruptedException e) {
+ * ...
+ * }
+ * }
+ * </pre>
+ *
+ * <hr>
+ * The above example does not differentiate the case where
+ * the memory usage has temporarily dropped below the usage threshold
+ * from the case where the memory usage remains above the threshould
+ * between two iterations. The usage threshold count returned by
+ * the {@link #getUsageThresholdCount} method
+ * can be used to determine
+ * if the memory usage has returned below the threshold
+ * between two polls.
+ * <p>
+ * Below shows another example that takes some action if a
+ * memory pool is under low memory and ignores the memory usage
+ * changes during the action processing time.
+ *
+ * <pre>
+ * // Assume the usage threshold is supported for this pool.
+ * // Set the threshold to myThreshold which determines if
+ * // the application will take some action under low memory condition.
+ * pool.setUsageThreshold(myThreshold);
+ *
+ * int prevCrossingCount = 0;
+ * while (true) {
+ * // A busy loop to detect when the memory usage
+ * // has exceeded the threshold.
+ * while (!pool.isUsageThresholdExceeded() ||
+ * pool.getUsageThresholdCount() == prevCrossingCount) {
+ * try {
+ * Thread.sleep(sometime)
+ * } catch (InterruptException e) {
+ * ....
+ * }
+ * }
+ *
+ * // Do some processing such as check for memory usage
+ * // and issue a warning
+ * ....
+ *
+ * // Gets the current threshold count. The busy loop will then
+ * // ignore any crossing of threshold happens during the processing.
+ * prevCrossingCount = pool.getUsageThresholdCount();
+ * }
+ * </pre><hr>
+ * </li>
+ * <li><a name="ThresholdNotification"><b>Usage Threshold Notifications</b></a>
+ * <p>
+ * Usage threshold notification will be emitted by {@link MemoryMXBean}.
+ * When the Java virtual machine detects that the memory usage of
+ * a memory pool has reached or exceeded the usage threshold
+ * the virtual machine will trigger the <tt>MemoryMXBean</tt> to emit an
+ * {@link MemoryNotificationInfo#MEMORY_THRESHOLD_EXCEEDED
+ * usage threshold exceeded notification}.
+ * Another usage threshold exceeded notification will not be
+ * generated until the usage has fallen below the threshold and
+ * then exceeded it again.
+ * <p>
+ * Below is an example code implementing the same logic as the
+ * first example above but using the usage threshold notification
+ * mechanism to detect low memory conditions instead of polling.
+ * In this example code, upon receiving notification, the notification
+ * listener notifies another thread to perform the actual action
+ * such as to redistribute outstanding tasks, stop receiving tasks,
+ * or resume receiving tasks.
+ * The <tt>handleNotification</tt> method should be designed to
+ * do a very minimal amount of work and return without delay to avoid
+ * causing delay in delivering subsequent notifications. Time-consuming
+ * actions should be performed by a separate thread.
+ * The notification listener may be invoked by multiple threads
+ * concurrently; so the tasks performed by the listener
+ * should be properly synchronized.
+ *
+ * <pre>
+ * class MyListener implements javax.management.NotificationListener {
+ * public void handleNotification(Notification notification, Object handback) {
+ * String notifType = notification.getType();
+ * if (notifType.equals(MemoryNotificationInfo.MEMORY_THRESHOLD_EXCEEDED)) {
+ * // potential low memory, notify another thread
+ * // to redistribute outstanding tasks to other VMs
+ * // and stop receiving new tasks.
+ * lowMemory = true;
+ * notifyAnotherThread(lowMemory);
+ * }
+ * }
+ * }
+ *
+ * // Register MyListener with MemoryMXBean
+ * MemoryMXBean mbean = ManagementFactory.getMemoryMXBean();
+ * NotificationEmitter emitter = (NotificationEmitter) mbean;
+ * MyListener listener = new MyListener();
+ * emitter.addNotificationListener(listener, null, null);
+ *
+ * // Assume this pool supports a usage threshold.
+ * // Set the threshold to myThreshold above which no new tasks
+ * // should be taken.
+ * pool.setUsageThreshold(myThreshold);
+ *
+ * // Usage threshold detection is enabled and notification will be
+ * // handled by MyListener. Continue for other processing.
+ * ....
+ *
+ * </pre>
+ * <hr>
+ * <p>
+ * There is no guarantee about when the <tt>MemoryMXBean</tt> will emit
+ * a threshold notification and when the notification will be delivered.
+ * When a notification listener is invoked, the memory usage of
+ * the memory pool may have crossed the usage threshold more
+ * than once.
+ * The {@link MemoryNotificationInfo#getCount} method returns the number
+ * of times that the memory usage has crossed the usage threshold
+ * at the point in time when the notification was constructed.
+ * It can be compared with the current usage threshold count returned
+ * by the {@link #getUsageThresholdCount} method to determine if
+ * such situation has occurred.
+ * </li>
+ * </ol>
+ *
+ * <h4><a name="CollectionThreshold">4. Collection Usage Threshold</a></h4>
+ *
+ * Collection usage threshold is a manageable attribute only applicable
+ * to some garbage-collected memory pools.
+ * After a Java virtual machine has expended effort in reclaiming memory
+ * space by recycling unused objects in a memory pool at garbage collection
+ * time, some number of bytes in the memory pools that are garbaged
+ * collected will still be in use. The collection usage threshold
+ * allows a value to be set for this number of bytes such
+ * that if the threshold is exceeded,
+ * a {@link MemoryNotificationInfo#MEMORY_THRESHOLD_EXCEEDED
+ * collection usage threshold exceeded notification}
+ * will be emitted by the {@link MemoryMXBean}.
+ * In addition, the {@link #getCollectionUsageThresholdCount
+ * collection usage threshold count} will then be incremented.
+ *
+ * <p>
+ * The {@link MemoryPoolMXBean#isCollectionUsageThresholdSupported} method can
+ * be used to determine if this functionality is supported.
+ *
+ * <p>
+ * A Java virtual machine performs collection usage threshold checking
+ * on a memory pool basis. This checking is enabled if the collection
+ * usage threshold is set to a positive value.
+ * If the collection usage threshold is set to zero, this checking
+ * is disabled on this memory pool. Default value is zero.
+ * The Java virtual machine performs the collection usage threshold
+ * checking at garbage collection time.
+ *
+ * <p>
+ * Some garbage-collected memory pools may
+ * choose not to support the collection usage threshold. For example,
+ * a memory pool is only managed by a continuous concurrent garbage
+ * collector. Objects can be allocated in this memory pool by some thread
+ * while the unused objects are reclaimed by the concurrent garbage
+ * collector simultaneously. Unless there is a well-defined
+ * garbage collection time which is the best appropriate time
+ * to check the memory usage, the collection usage threshold should not
+ * be supported.
+ *
+ * <p>
+ * The collection usage threshold is designed for monitoring the memory usage
+ * after the Java virtual machine has expended effort in reclaiming
+ * memory space. The collection usage could also be monitored
+ * by the polling and threshold notification mechanism
+ * described above for the <a href="#UsageThreshold">usage threshold</a>
+ * in a similar fashion.
+ *
+ * @see <a href="../../../javax/management/package-summary.html">
+ * JMX Specification.</a>
+ * @see <a href="package-summary.html#examples">
+ * Ways to Access MXBeans</a>
+ *
+ * @author Mandy Chung
+ * @since 1.5
+ */
+public interface MemoryPoolMXBean {
+ /**
+ * Returns the name representing this memory pool.
+ *
+ * @return the name of this memory pool.
+ */
+ public String getName();
+
+ /**
+ * Returns the type of this memory pool.
+ *
+ * <p>
+ * <b>MBeanServer access</b>:<br>
+ * The mapped type of <tt>MemoryType</tt> is <tt>String</tt>
+ * and the value is the name of the <tt>MemoryType</tt>.
+ *
+ * @return the type of this memory pool.
+ */
+ public MemoryType getType();
+
+ /**
+ * Returns an estimate of the memory usage of this memory pool.
+ * This method returns <tt>null</tt>
+ * if this memory pool is not valid (i.e. no longer exists).
+ *
+ * <p>
+ * This method requests the Java virtual machine to make
+ * a best-effort estimate of the current memory usage of this
+ * memory pool. For some memory pools, this method may be an
+ * expensive operation that requires some computation to determine
+ * the estimate. An implementation should document when
+ * this is the case.
+ *
+ * <p>This method is designed for use in monitoring system
+ * memory usage and detecting low memory condition.
+ *
+ * <p>
+ * <b>MBeanServer access</b>:<br>
+ * The mapped type of <tt>MemoryUsage</tt> is
+ * <tt>CompositeData</tt> with attributes as specified in
+ * {@link MemoryUsage#from MemoryUsage}.
+ *
+ * @return a {@link MemoryUsage} object; or <tt>null</tt> if
+ * this pool not valid.
+ */
+ public MemoryUsage getUsage();
+
+ /**
+ * Returns the peak memory usage of this memory pool since the
+ * Java virtual machine was started or since the peak was reset.
+ * This method returns <tt>null</tt>
+ * if this memory pool is not valid (i.e. no longer exists).
+ *
+ * <p>
+ * <b>MBeanServer access</b>:<br>
+ * The mapped type of <tt>MemoryUsage</tt> is
+ * <tt>CompositeData</tt> with attributes as specified in
+ * {@link MemoryUsage#from MemoryUsage}.
+ *
+ * @return a {@link MemoryUsage} object representing the peak
+ * memory usage; or <tt>null</tt> if this pool is not valid.
+ *
+ */
+ public MemoryUsage getPeakUsage();
+
+ /**
+ * Resets the peak memory usage statistic of this memory pool
+ * to the current memory usage.
+ *
+ * @throws java.lang.SecurityException if a security manager
+ * exists and the caller does not have
+ * ManagementPermission("control").
+ */
+ public void resetPeakUsage();
+
+ /**
+ * Tests if this memory pool is valid in the Java virtual
+ * machine. A memory pool becomes invalid once the Java virtual
+ * machine removes it from the memory system.
+ *
+ * @return <tt>true</tt> if the memory pool is valid in the running
+ * Java virtual machine;
+ * <tt>false</tt> otherwise.
+ */
+ public boolean isValid();
+
+ /**
+ * Returns the name of memory managers that manages this memory pool.
+ * Each memory pool will be managed by at least one memory manager.
+ *
+ * @return an array of <tt>String</tt> objects, each is the name of
+ * a memory manager managing this memory pool.
+ */
+ public String[] getMemoryManagerNames();
+
+ /**
+ * Returns the usage threshold value of this memory pool in bytes.
+ * Each memory pool has a platform-dependent default threshold value.
+ * The current usage threshold can be changed via the
+ * {@link #setUsageThreshold setUsageThreshold} method.
+ *
+ * @return the usage threshold value of this memory pool in bytes.
+ *
+ * @throws UnsupportedOperationException if this memory pool
+ * does not support a usage threshold.
+ *
+ * @see #isUsageThresholdSupported
+ */
+ public long getUsageThreshold();
+
+ /**
+ * Sets the threshold of this memory pool to the given <tt>threshold</tt>
+ * value if this memory pool supports the usage threshold.
+ * The usage threshold crossing checking is enabled in this memory pool
+ * if the threshold is set to a positive value.
+ * The usage threshold crossing checking is disabled
+ * if it is set to zero.
+ *
+ * @param threshold the new threshold value in bytes. Must be non-negative.
+ *
+ * @throws IllegalArgumentException if <tt>threshold</tt> is negative
+ * or greater than the maximum amount of memory for
+ * this memory pool if defined.
+ *
+ * @throws UnsupportedOperationException if this memory pool
+ * does not support a usage threshold.
+ *
+ * @throws java.lang.SecurityException if a security manager
+ * exists and the caller does not have
+ * ManagementPermission("control").
+ *
+ * @see #isUsageThresholdSupported
+ * @see <a href="#UsageThreshold">Usage threshold</a>
+ */
+ public void setUsageThreshold(long threshold);
+
+ /**
+ * Tests if the memory usage of this memory pool
+ * reaches or exceeds its usage threshold value.
+ *
+ * @return <tt>true</tt> if the memory usage of
+ * this memory pool reaches or exceeds the threshold value;
+ * <tt>false</tt> otherwise.
+ *
+ * @throws UnsupportedOperationException if this memory pool
+ * does not support a usage threshold.
+ */
+ public boolean isUsageThresholdExceeded();
+
+ /**
+ * Returns the number of times that the memory usage has crossed
+ * the usage threshold.
+ *
+ * @return the number of times that the memory usage
+ * has crossed its usage threshold value.
+ *
+ * @throws UnsupportedOperationException if this memory pool
+ * does not support a usage threshold.
+ */
+ public long getUsageThresholdCount();
+
+ /**
+ * Tests if this memory pool supports usage threshold.
+ *
+ * @return <tt>true</tt> if this memory pool supports usage threshold;
+ * <tt>false</tt> otherwise.
+ */
+ public boolean isUsageThresholdSupported();
+
+ /**
+ * Returns the collection usage threshold value of this memory pool
+ * in bytes. The default value is zero. The collection usage
+ * threshold can be changed via the
+ * {@link #setCollectionUsageThreshold setCollectionUsageThreshold} method.
+ *
+ * @return the collection usage threshold of this memory pool in bytes.
+ *
+ * @throws UnsupportedOperationException if this memory pool
+ * does not support a collection usage threshold.
+ *
+ * @see #isCollectionUsageThresholdSupported
+ */
+ public long getCollectionUsageThreshold();
+
+ /**
+ * Sets the collection usage threshold of this memory pool to
+ * the given <tt>threshold</tt> value.
+ * When this threshold is set to positive, the Java virtual machine
+ * will check the memory usage at its best appropriate time after it has
+ * expended effort in recycling unused objects in this memory pool.
+ * <p>
+ * The collection usage threshold crossing checking is enabled
+ * in this memory pool if the threshold is set to a positive value.
+ * The collection usage threshold crossing checking is disabled
+ * if it is set to zero.
+ *
+ * @param threshold the new collection usage threshold value in bytes.
+ * Must be non-negative.
+ *
+ * @throws IllegalArgumentException if <tt>threshold</tt> is negative
+ * or greater than the maximum amount of memory for
+ * this memory pool if defined.
+ *
+ * @throws UnsupportedOperationException if this memory pool
+ * does not support a collection usage threshold.
+ *
+ * @throws java.lang.SecurityException if a security manager
+ * exists and the caller does not have
+ * ManagementPermission("control").
+ *
+ * @see #isCollectionUsageThresholdSupported
+ * @see <a href="#CollectionThreshold">Collection usage threshold</a>
+ */
+ public void setCollectionUsageThreshold(long threshold);
+
+ /**
+ * Tests if the memory usage of this memory pool after
+ * the most recent collection on which the Java virtual
+ * machine has expended effort has reached or
+ * exceeded its collection usage threshold.
+ * This method does not request the Java virtual
+ * machine to perform any garbage collection other than its normal
+ * automatic memory management.
+ *
+ * @return <tt>true</tt> if the memory usage of this memory pool
+ * reaches or exceeds the collection usage threshold value
+ * in the most recent collection;
+ * <tt>false</tt> otherwise.
+ *
+ * @throws UnsupportedOperationException if this memory pool
+ * does not support a usage threshold.
+ */
+ public boolean isCollectionUsageThresholdExceeded();
+
+ /**
+ * Returns the number of times that the Java virtual machine
+ * has detected that the memory usage has reached or
+ * exceeded the collection usage threshold.
+ *
+ * @return the number of times that the memory
+ * usage has reached or exceeded the collection usage threshold.
+ *
+ * @throws UnsupportedOperationException if this memory pool
+ * does not support a collection usage threshold.
+ *
+ * @see #isCollectionUsageThresholdSupported
+ */
+ public long getCollectionUsageThresholdCount();
+
+ /**
+ * Returns the memory usage after the Java virtual machine
+ * most recently expended effort in recycling unused objects
+ * in this memory pool.
+ * This method does not request the Java virtual
+ * machine to perform any garbage collection other than its normal
+ * automatic memory management.
+ * This method returns <tt>null</tt> if the Java virtual
+ * machine does not support this method.
+ *
+ * <p>
+ * <b>MBeanServer access</b>:<br>
+ * The mapped type of <tt>MemoryUsage</tt> is
+ * <tt>CompositeData</tt> with attributes as specified in
+ * {@link MemoryUsage#from MemoryUsage}.
+ *
+ * @return a {@link MemoryUsage} representing the memory usage of
+ * this memory pool after the Java virtual machine most recently
+ * expended effort in recycling unused objects;
+ * <tt>null</tt> if this method is not supported.
+ */
+ public MemoryUsage getCollectionUsage();
+
+ /**
+ * Tests if this memory pool supports a collection usage threshold.
+ *
+ * @return <tt>true</tt> if this memory pool supports the
+ * collection usage threshold; <tt>false</tt> otherwise.
+ */
+ public boolean isCollectionUsageThresholdSupported();
+}