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/*
Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this code 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.onap.dcae.cdf.util.threads;
import java.util.LinkedList;
import java.util.List;
/**
* Various utility functions dealing with threads
*/
public class ThreadUtils {
/**
* Get a list of all threads.
*
* @return an array of threads
*/
public static Thread[] getAllThreads() {
ThreadGroup rootGroup = getRootGroup();
int noThreads = rootGroup.activeCount(); // returns an estimated count of active threads
Thread[] threads = new Thread[noThreads + 1];
rootGroup.enumerate(threads);
while ( rootGroup.enumerate( threads, true ) == threads.length ) { // iterate if we filled up the array
threads = new Thread[ threads.length + noThreads ];
}
// remove null threads
LinkedList<Thread> lthreads = new LinkedList<Thread>();
for (Thread thread: threads)
if (thread != null)
lthreads.push(thread);
return lthreads.toArray(new Thread[0]);
}
/**
* Get a list of all threads with a given thread name.
*
* @param name the name to look for
* @return an array of threads with that name
*/
public static Thread[] getNamedThreads(final String name) {
Thread[] allThreads = getAllThreads();
LinkedList<Thread> lthreads = new LinkedList<Thread>();
for (Thread thread: allThreads)
if (thread.getName().equals(name))
lthreads.push(thread);
return lthreads.toArray(new Thread[0]);
}
/**
* Get the ultimate root of the threads
*
* @return the root thread
*/
public static ThreadGroup getRootGroup() {
ThreadGroup rootGroup = Thread.currentThread( ).getThreadGroup( );
ThreadGroup parentGroup;
while ( ( parentGroup = rootGroup.getParent() ) != null ) {
rootGroup = parentGroup;
}
return rootGroup;
}
public static void main(String args[]) throws Exception {
System.out.println("==== get Root Threads ====");
System.out.println("Root thread = " + getRootGroup().getName());
System.out.println("==== get All Threads ====");
Thread[] threads = getAllThreads();
for (int i = 0; i < threads.length; i++)
System.out.println("Thread No:" + i + " = " + threads[i].getName());
System.out.println("==== getNamedThreads(main) ====");
threads = getNamedThreads("main");
for (int i = 0; i < threads.length; i++)
System.out.println("Thread No:" + i + " = " + threads[i].getName());
}
}
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