/**
*
* 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 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;
import javax.management.JMException;
import javax.management.MBeanServer;
import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;
/**
* 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 MBeanServer beanServer;
private static final ObjectName nioDirectPool;
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;
try {
n = new ObjectName("java.nio:type=BufferPool,name=direct");
} catch (MalformedObjectNameException e) {
LOG.warn("Unable to initialize ObjectName for DirectByteBuffer allocations.");
} finally {
nioDirectPool = n;
}
if (nioDirectPool != null) {
s = ManagementFactory.getPlatformMBeanServer();
}
beanServer = s;
}
/**
* @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 (beanServer == null || nioDirectPool == null) return 0;
try {
Long value = (Long) beanServer.getAttribute(nioDirectPool, "MemoryUsed");
return value == null ? 0 : value;
} catch (JMException e) {
LOG.debug("Failed to retrieve nio.BufferPool direct MemoryUsed");
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);
}
}