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/*
* Copyright (c) 2009, Chris Miller
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* 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.
*/
package uk.me.parabola.splitter;
/**
* Periodically outputs the elapsed time and amount of memory used by the VM
*
* @author Chris Miller
*/
public class JVMHealthMonitor
{
private final Thread statusThread
;
private static long startTime
;
/**
* Starts a daemon thread that will periodically report the state of the JVM (heap usage).
* This method just needs to be called once and there's nothing else to do. The background
* thread will terminate automatically when the application exits.
*
* @param statusFrequency the number of seconds to sleep between each status update.
*/
public JVMHealthMonitor
(final long statusFrequency
) {
startTime =
System.
currentTimeMillis();
statusThread =
new Thread(new Runnable() {
@
Override
public void run
() {
int iter=
0;
while (true) {
iter++
;
if (iter
%10 ==
0) {
System.
out.
println("***** Full GC *****");
System.
gc();
}
long maxMem =
Runtime.
getRuntime().
maxMemory() /
1024 /
1024;
long totalMem =
Runtime.
getRuntime().
totalMemory() /
1024 /
1024;
long freeMem =
Runtime.
getRuntime().
freeMemory() /
1024 /
1024;
long usedMem = totalMem - freeMem
;
System.
out.
println("Elapsed time: " + getElapsedTime
() +
" Memory: Current " + totalMem +
"MB (" + usedMem +
"MB used, " + freeMem +
"MB free) Max " + maxMem +
"MB");
try {
Thread.
sleep(statusFrequency
* 1000L
);
}
catch (InterruptedException e
) {
System.
out.
println("JVMHealthMonitor sleep was interrupted. Ignoring.");
}
}
}
}
);
statusThread.
setDaemon(true);
statusThread.
setName("JVMHealthMonitor");
}
public void start
(){
if (!statusThread.
isAlive())
statusThread.
start();
}
protected static String getElapsedTime
() {
long elapsed =
(System.
currentTimeMillis() - startTime
) /
1000;
long seconds = elapsed
% 60;
long minutes = elapsed /
60 % 60;
long hours = elapsed /
(60L
* 60) % 60;
StringBuilder buf =
new StringBuilder(20);
if (hours
> 0)
buf.
append(hours
).
append("h ");
if (hours
> 0 || minutes
> 0)
buf.
append(minutes
).
append("m ");
buf.
append(seconds
).
append('s');
return buf.
toString();
}
}