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/**
* Memory
* Copyright 2005 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
* First published 22.09.2005 on http://yacy.net
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program in the file lgpl21.txt
* If not, see <http://www.gnu.org/licenses/>.
*/
package net.yacy.cora.util;
import java.lang.management.ManagementFactory;
import java.lang.management.ThreadInfo;
public class Memory {
private static final Runtime runtime = Runtime.getRuntime();
/**
* memory that is free without increasing of total memory taken from os
* @return bytes
*/
public static final long free() {
return runtime.freeMemory();
}
/**
* memory that is available including increasing total memory up to maximum
* @return bytes
*/
public static final long available() {
return maxMemory() - total() + free();
}
/**
* maximum memory the Java virtual will allocate machine; may vary over time in some cases
* @return bytes
*/
public static final long maxMemory() {
return runtime.maxMemory(); // can be Long.MAX_VALUE if unlimited
}
/**
* currently allocated memory in the Java virtual machine; may vary over time
* @return bytes
*/
public static final long total() {
return runtime.totalMemory();
}
/**
* memory that is currently bound in objects
* @return used bytes
*/
public static final long used() {
return total() - free();
}
/**
* get number of CPU cores
* @return number of CPU cores
*/
public static final long cores() {
return runtime.availableProcessors();
}
/**
* get the system load within the last minute
* @return the system load or a negative number if the load is not available
*/
public static double load() {
return ManagementFactory.getOperatingSystemMXBean().getSystemLoadAverage();
}
/**
* find out the number of thread deadlocks. WARNING: this is a time-consuming task
* @return the number of deadlocked threads
*/
public static long deadlocks() {
long[] deadlockIDs = ManagementFactory.getThreadMXBean().findDeadlockedThreads();
if (deadlockIDs == null) return 0;
return deadlockIDs.length;
}
/**
* write deadlocked threads as to the log as warning
*/
public static void logDeadlocks() {
long[] deadlockIDs = ManagementFactory.getThreadMXBean().findDeadlockedThreads();
if (deadlockIDs == null) return;
ThreadInfo[] infos = ManagementFactory.getThreadMXBean().getThreadInfo(deadlockIDs, true, true);
for (ThreadInfo ti : infos) {
ConcurrentLog.warn("DEADLOCKREPORT", ti.toString());
}
}
}
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