ThreadsCpuTimer.java
/*
** Module : ThreadsCpuTimer.java
** Abstract : It extends NanoTimer for measuring CPU utilization of threads.
**
** Copyright (c) 2021, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------------Description----------------------------------------
** 001 SBI 20211104 Implemented jmx bean for measuring CPU utilization of threads.
** RFB 20211117 Minor javadoc error corrected.
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
** Under Section 7 of the GNU Affero GPL version 3, the following additional
** terms apply to the works covered under the License. These additional terms
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** Affero GPL version 3 and may not be removed by you.
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** 0. Attribution Requirement.
**
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*/
package com.goldencode.p2j.jmx;
import java.lang.management.*;
import java.util.*;
import java.util.function.*;
/** Represents threads CPU timer for measuring CPU utilization of threads. */
public class ThreadsCpuTimer
extends NanoTimer
{
/** The management interface for the JVM thread system */
private final ThreadMXBean jmxBean = ManagementFactory.getThreadMXBean();
/** The flag that indicates that this JVM supports threads monitoring capabilities */
private final boolean threadsMonitoringSupported = jmxBean.isThreadCpuTimeSupported();
/** Holds the initial points for CPU utilization measurements of threads */
private final Map<Long, Long> cpuStartTimes = new LinkedHashMap<>();
/** Holds the initial points for CPU utilization measurements of threads in a user mode*/
private final Map<Long, Long> userStartTimes = new LinkedHashMap<>();
/** Holds the current threads at the time of this measurement */
private long[] threadIds;
/** Holds the current thread id used for this measurement */
private long currentThreadId;
/** Holds a counter for storing the measurement results */
private final ThreadsCpuMBean counter;
/**
* Create and register its instance.
*
* @param counter
* The instance of NanoCounter
*
* @return Threads CPU timer
*/
public static ThreadsCpuTimer getInstance(ThreadsCpuMBean counter)
{
ThreadsCpuTimer timer = new ThreadsCpuTimer(counter, counter::update);
timer.setEnabler(timer::setEnabled); //prevent GC
counter.register(timer.getEnabler());
return timer;
}
/**
* Creates this thread CPU timer.
*
* @param counter
* The threads CPU counter jmx interface
* @param publish
* The consumer of NanoTimer measurement results
*/
protected ThreadsCpuTimer(ThreadsCpuMBean counter, LongConsumer publish)
{
super(publish);
this.counter = counter;
}
/**
* Start measurement operation.
*/
public void start()
{
super.start();
if (threadsMonitoringSupported)
{
try
{
threadIds = jmxBean.getAllThreadIds();
}
catch(SecurityException ex)
{
}
if (threadIds == null)
{
return;
}
currentThreadId = Thread.currentThread().getId();
counter.setCurrentThread(currentThreadId);
cpuStartTimes.put(currentThreadId, jmxBean.getThreadCpuTime(currentThreadId));
userStartTimes.put(currentThreadId, jmxBean.getThreadUserTime(currentThreadId));
for (int i = 0; i < threadIds.length; i++)
{
long tid = threadIds[i];
if (tid != currentThreadId)
{
cpuStartTimes.put(tid, jmxBean.getThreadCpuTime(tid));
userStartTimes.put(tid, jmxBean.getThreadUserTime(tid));
}
}
}
}
/** Stop operation and update counter */
public void stop()
{
super.stop();
if (threadsMonitoringSupported && (threadIds != null))
{
counter.updateThreadElapsedCpuTime( currentThreadId, (jmxBean.getThreadCpuTime(currentThreadId) - cpuStartTimes.get(currentThreadId)));
counter.updateThreadElapsedUserTime(currentThreadId, (jmxBean.getThreadUserTime(currentThreadId) - userStartTimes.get(currentThreadId)));
for (int i = 0; i < threadIds.length; i++)
{
long tid = threadIds[i];
if (tid != currentThreadId)
{
counter.updateThreadElapsedCpuTime( tid, (jmxBean.getThreadCpuTime(tid) - cpuStartTimes.get(tid)));
counter.updateThreadElapsedUserTime(tid, (jmxBean.getThreadUserTime(tid) - userStartTimes.get(tid)));
}
}
}
}
/**
* Enables or disables thread CPU time measurement.
*
* @param enable
* The boolean value for enabling or disabling thread CPU time measurement.
*/
@Override
public void setEnabled(boolean enable)
{
super.setEnabled(enable);
if (jmxBean.isThreadCpuTimeSupported())
{
jmxBean.setThreadCpuTimeEnabled(enable);
}
}
}