org.apache.hadoop.hbase.util.DirectMemoryUtils.java Source code

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Here is the source code for org.apache.hadoop.hbase.util.DirectMemoryUtils.java

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/**
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hbase.util;

import java.lang.management.ManagementFactory;
import java.lang.management.RuntimeMXBean;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.nio.ByteBuffer;
import java.util.List;

import javax.management.JMException;
import javax.management.MBeanServer;
import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;

import com.google.common.base.Preconditions;

/**
 * Utilities for interacting with and monitoring DirectByteBuffer allocations.
 */
@InterfaceAudience.Private
@InterfaceStability.Evolving
public class DirectMemoryUtils {
    private static final Log LOG = LogFactory.getLog(DirectMemoryUtils.class);
    private static final String MEMORY_USED = "MemoryUsed";
    private static final MBeanServer BEAN_SERVER;
    private static final ObjectName NIO_DIRECT_POOL;
    private static final boolean HAS_MEMORY_USED_ATTRIBUTE;

    static {
        // initialize singletons. Only maintain a reference to the MBeanServer if
        // we're able to consume it -- hence convoluted logic.
        ObjectName n = null;
        MBeanServer s = null;
        Object a = null;
        try {
            n = new ObjectName("java.nio:type=BufferPool,name=direct");
        } catch (MalformedObjectNameException e) {
            LOG.warn("Unable to initialize ObjectName for DirectByteBuffer allocations.");
        } finally {
            NIO_DIRECT_POOL = n;
        }
        if (NIO_DIRECT_POOL != null) {
            s = ManagementFactory.getPlatformMBeanServer();
        }
        BEAN_SERVER = s;
        if (BEAN_SERVER != null) {
            try {
                a = BEAN_SERVER.getAttribute(NIO_DIRECT_POOL, MEMORY_USED);
            } catch (JMException e) {
                LOG.debug("Failed to retrieve nio.BufferPool direct MemoryUsed attribute: " + e);
            }
        }
        HAS_MEMORY_USED_ATTRIBUTE = a != null;
    }

    /**
     * @return the setting of -XX:MaxDirectMemorySize as a long. Returns 0 if
     *         -XX:MaxDirectMemorySize is not set.
     */
    public static long getDirectMemorySize() {
        RuntimeMXBean runtimemxBean = ManagementFactory.getRuntimeMXBean();
        List<String> arguments = runtimemxBean.getInputArguments();
        long multiplier = 1; //for the byte case.
        for (String s : arguments) {
            if (s.contains("-XX:MaxDirectMemorySize=")) {
                String memSize = s.toLowerCase().replace("-xx:maxdirectmemorysize=", "").trim();

                if (memSize.contains("k")) {
                    multiplier = 1024;
                }

                else if (memSize.contains("m")) {
                    multiplier = 1048576;
                }

                else if (memSize.contains("g")) {
                    multiplier = 1073741824;
                }
                memSize = memSize.replaceAll("[^\\d]", "");

                long retValue = Long.parseLong(memSize);
                return retValue * multiplier;
            }
        }
        return 0;
    }

    /**
     * @return the current amount of direct memory used.
     */
    public static long getDirectMemoryUsage() {
        if (BEAN_SERVER == null || NIO_DIRECT_POOL == null || !HAS_MEMORY_USED_ATTRIBUTE)
            return 0;
        try {
            Long value = (Long) BEAN_SERVER.getAttribute(NIO_DIRECT_POOL, MEMORY_USED);
            return value == null ? 0 : value;
        } catch (JMException e) {
            // should print further diagnostic information?
            return 0;
        }
    }

    /**
     * DirectByteBuffers are garbage collected by using a phantom reference and a
     * reference queue. Every once a while, the JVM checks the reference queue and
     * cleans the DirectByteBuffers. However, as this doesn't happen
     * immediately after discarding all references to a DirectByteBuffer, it's
     * easy to OutOfMemoryError yourself using DirectByteBuffers. This function
     * explicitly calls the Cleaner method of a DirectByteBuffer.
     * 
     * @param toBeDestroyed
     *          The DirectByteBuffer that will be "cleaned". Utilizes reflection.
     *          
     */
    public static void destroyDirectByteBuffer(ByteBuffer toBeDestroyed) throws IllegalArgumentException,
            IllegalAccessException, InvocationTargetException, SecurityException, NoSuchMethodException {

        Preconditions.checkArgument(toBeDestroyed.isDirect(), "toBeDestroyed isn't direct!");

        Method cleanerMethod = toBeDestroyed.getClass().getMethod("cleaner");
        cleanerMethod.setAccessible(true);
        Object cleaner = cleanerMethod.invoke(toBeDestroyed);
        Method cleanMethod = cleaner.getClass().getMethod("clean");
        cleanMethod.setAccessible(true);
        cleanMethod.invoke(cleaner);
    }
}