Current File : //home/waritko/yacy/source/net/yacy/kelondro/util/MemoryControl.java
// MemoryControl.java
// -------------------------------------------
// (C) 2005 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 22.09.2005 on http://yacy.net
//
// $LastChangedDate$
// $LastChangedRevision$
// $LastChangedBy$
//
// LICENSE
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program 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 for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package net.yacy.kelondro.util;
import java.util.concurrent.atomic.AtomicBoolean;
import net.yacy.cora.util.ConcurrentLog;
/**
* Use this to get information about memory usage or try to free some memory
*/
public class MemoryControl {
private static AtomicBoolean shortStatus = new AtomicBoolean(false);
private static boolean simulatedShortStatus = false, usingStandardStrategy = true;
private static MemoryStrategy strategy;
private static MemoryStrategy getStrategy() {
if (strategy == null || MemoryStrategy.hasError()) {
if (!usingStandardStrategy) {
strategy = new GenerationMemoryStrategy();
// if (strategy.hasError()) { // perhaps we do have a G1
// strategy = new G1MemoryStrategy();
// }
// fall back if error detected
if (MemoryStrategy.hasError()) {
usingStandardStrategy = true;
strategy = new StandardMemoryStrategy();
}
} else {
strategy = new StandardMemoryStrategy();
}
}
return strategy;
}
public final static void setStandardStrategy(final boolean std) {
if (usingStandardStrategy != std) {
usingStandardStrategy = std;
strategy = null;
}
}
/**
* @return the name of the used strategy
*/
public final static String getStrategyName() {
getStrategy();
return MemoryStrategy.getName();
}
/**
* Runs the garbage collector if last garbage collection is more than last millis ago
* @param last time which must be passed since lased gc
* @param info additional info for log
*/
public final synchronized static boolean gc(final int last, final String info) { // thq
return getStrategy().gc(last, info);
}
/**
* memory that is free without increasing of total memory taken from os
* @return bytes
*/
public static final long free() {
return getStrategy().free();
}
/**
* memory that is available including increasing total memory up to maximum
* @return bytes
*/
public static final long available() {
long available = getStrategy().available();
return available;
}
/**
* maximum memory the Java virtual will allocate machine; may vary over time in some cases
* @return bytes
*/
public static final long maxMemory()
{
return getStrategy().maxMemory();
}
/**
* currently allocated memory in the Java virtual machine; may vary over time
* @return bytes
*/
public static final long total()
{
return getStrategy().total();
}
/**
* check for a specified amount of bytes
*
* @param size the requested amount of free memory in bytes
* @param force specifies whether risk an expensive GC
* @return whether enough memory could be freed (or is free) or not
*/
public static boolean request(final long size, final boolean force) {
if (size < 1024) return true; // to speed up things. If this would fail, it would be much too late to check this.
return getStrategy().request(size, force, shortStatus);
}
/**
* the simulated short status can be set to find out if the short status has effects to the system
* @param status
*/
public static void setSimulatedShortStatus(final boolean status) {
simulatedShortStatus = status;
}
/**
* the simulated short status can be retrieved to show that option in online interfaces
* @return
*/
public static boolean getSimulatedShortStatus() {
return simulatedShortStatus;
}
/**
* @return if last request failed
*/
public static boolean shortStatus() {
//if (shortStatus) System.out.println("**** SHORT MEMORY ****");
return simulatedShortStatus || shortStatus.get();
}
/**
* memory that is currently bound in objects
* @return used bytes
*/
public static long used() {
return getStrategy().used();
}
/**
* @return if Memory seams to be in a proper state
*/
public static boolean properState() {
return getStrategy().properState();
}
/**
* forced enable properState - StandardMemoryStrategy only
*/
public static void resetProperState() {
getStrategy().resetProperState();
}
/**
* set the memory to be available for properState - StandardMemoryStrategy only
*/
public static void setProperMbyte(final long mbyte) {
getStrategy().setProperMbyte(mbyte);
}
/**
* main
* @param args use 'force' to request by force, use 'std' / 'gen' to specify strategy
*/
public static void main(final String[] args) {
long beginTime = System.nanoTime();
int i = 0;
try {
// try this with different strategy and compare results
final int mb = 1024 * 1024;
boolean force = false;
for (final String arg : args) {
if (arg.equals("force"))
force = true;
if (arg.equalsIgnoreCase("gen"))
usingStandardStrategy = false;
if (arg.equalsIgnoreCase("std"))
usingStandardStrategy = true;
}
System.out.println("vm: " + System.getProperty("java.vm.version"));
System.out.println("computed max = " + (maxMemory() / mb) + " mb");
System.out.println("using " + getStrategyName());
if(force) {
System.out.println("forcing garbage collector when requesting");
} else {
System.out.println("not forcing garbage collector when requesting");
}
final byte[][] x = new byte[100000][];
for (i = 0; i < 100000; i++) {
if (request(mb, force)) {
x[i] = new byte[mb];
System.out
.println("used = " + i + " / " + (used() / mb) + ", total = " + (total() / mb) + ", free = "
+ (free() / mb) + ", max = " + (maxMemory() / mb) + ", avail = "
+ (available() / mb)
+ (usingStandardStrategy
? ", averageGC = "
+ ((StandardMemoryStrategy) getStrategy()).getAverageGCFree()
: ""));
} else {
System.out.println("No more memory available!");
break;
}
}
} finally {
long time = System.nanoTime() - beginTime;
System.out.println("Test run in " + time / 1000000 + " ms");
ConcurrentLog.shutdown();
System.out.println("Succesfull requests : " + i);
}
}
}
Mini Shell