Thanks Ronald. I made a couple mods. I added the below to the Group fields:
Comparator threadComparitor =
new Comparator() {
public int compare(Object o1, Object o2) {
return (((Thread) o1).getName()).compareTo
(((Thread) o2).getName());
} // end compare method
};Then I was able to sort the Thread array directly...
java.util.Arrays.sort(ta, 0, nr, threadComparitor);
I also added another tab before the printing of Thread lines so that they appear to be contained in their ThreadGroup rather than appearing as a peer to it.
out.println(prefix + "\tT " + ta[i].toString() );
Regards, Bob Feretich
Ronald Klop wrote:
Hello,
I use the attached .jsp to view all the threads.
Ronald.
On Fri Jan 28 12:33:10 CET 2005 Tomcat Users List <tomcat-user@jakarta.apache.org> wrote:
There is a June 2002 mail thread that discusses "How to list all Threads in the JVM?". It includes a handy Java class that is supposed to return all sorts of information on these threads.
But, the class does not seem to examine the entire ThreadGroup tree. The constructor creates an ArrayList of ThreadGroups along a tree branch from the current thread to the root, but other tree branches are ignored.
Unfortunately, the mail thread ended without any further discussion.
Is there some significance between this branch of the ThreadGroup tree and the way Tomcat creates ThreadGroups or is this a bug in the suggested code?
Also getThreadCount() seems to return the number of ThreadGroups in the branch rather than the number of Threads in the JVM.
Regards, Bob Feretich
package com.mpi.chemi.portal.util; import java.util.ArrayList; import java.util.List; import org.apache.log4j.Logger;
public class SystemThreadList { /** * The list of threads. */ private ArrayList _threads;
/** * Constructor. Creates a list of all the * threads running in the JVM in the system. */ public SystemThreadList() { _threads = new ArrayList();
ThreadGroup tg = Thread.currentThread().getThreadGroup(); if(tg != null) { _threads.add(tg); while(tg.getParent() != null) { tg = tg.getParent(); if(tg != null) { _threads.add(tg); } } } }
/** * Returns the thread count. * * @return int */ public int getThreadCount() { if(_threads == null) return -1; else return _threads.size(); }
/** * Returns the thread group at the given index. * * @param index * @return ThreadGroup */ public ThreadGroup getThreadGroup(int index) { if(getThreadCount() < 1) return null; else if((index < 0) || (index > (getThreadCount() - 1))) return null; else return (ThreadGroup)_threads.get(index); }
/** * Prints out the list of threads. */ public void printThreads() { System.out.println(toString()); }
/** * Returns a String representation of this * SystemThreadList. * * @return String */ public String toString() { StringBuffer sb = new StringBuffer("[SystemThreadList:\n");
if(getThreadCount() < 1) { sb.append(" No Threads "); } else { for(int i = 0; i < getThreadCount(); i++) { sb.append(" ThreadGroup " + i + "= "); sb.append(getThreadGroup(i).toString()); sb.append(", activeCount = " + getThreadGroup(i).activeCount()); sb.append("\n"); } }
// Total active count sb.append(" totalActiveCount = " + getTotalActiveCount() + "\n");
sb.append(" (End of SystemThreadList)]"); return sb.toString(); }
/** * Returns the total active count: goes over * every group in the list, and sums their activeCount() * results. * * @return int */ public int getTotalActiveCount() { if(getThreadCount() < 1) return 0; else { int totalActiveCount = 0; ThreadGroup tg = null; for(int i = 0; i < getThreadCount(); i++) { tg = getThreadGroup(i); totalActiveCount += tg.activeCount(); }
return totalActiveCount; } }
/** * Returns the root thread group, i.e. * the one whose parent is null. * * @return ThreadGroup */ public ThreadGroup getRootThreadGroup() { if(getThreadCount() < 1) return null; else { ThreadGroup tg = null; for(int i = 0; i < getThreadCount(); i++) { tg = getThreadGroup(i); if(tg.getParent() == null) { return tg; } }
// If we got here, we didn't find one, so return null. return null; } }
/** * Gets all the threads. * * @return Thread[] */ public Thread[] getAllThreads() { int estimatedCount = getTotalActiveCount();
// Start with array twice size of estimated, // to be safe. Trim later. Thread[] estimatedThreads = new Thread[estimatedCount * 2];
// Locate root group ThreadGroup rootGroup = getRootThreadGroup(); if(rootGroup == null) { return null; }
int actualCount = rootGroup.enumerate(estimatedThreads, true);
// Check that something was returned if(actualCount < 1) return null;
// Copy into actualThreads of correct size Thread[] actualThreads = new Thread[actualCount]; for(int i = 0; i < actualThreads.length; i++) { actualThreads[i] = estimatedThreads[i]; }
return actualThreads; }
/** * Gets all the threads whose name contains the * given string. The search is CASE-SENSITIVE. * * @param nameMatch * @return List */ public List getThreadsWithNameMatch(String nameMatch) { Thread[] allThreads = getAllThreads(); if((allThreads == null) || (allThreads.length < 1)) { return null; } else { ArrayList matchingThreads = new ArrayList(); for(int i = 0; i < allThreads.length; i++) { if(allThreads[i].getName().indexOf(nameMatch) > -1) matchingThreads.add(allThreads[i]); }
if((matchingThreads == null) || (matchingThreads.size() < 1)) return null; else return matchingThreads; } }
/** * Tries to destory the root group. */ public void destroyRootThreadGroup() { ThreadGroup rootGroup = getRootThreadGroup(); if(rootGroup == null) { return; } else { rootGroup.destroy(); } }
/** * Main. Tests the functionality. * * @param args */ public static void main(String[] args) { System.out.println("SystemThreadList: main(): starting.");
// Create list SystemThreadList stl = new SystemThreadList();
// Print info System.out.println("SystemThreadList: main(): calling SystemThreadList.toString()."); stl.printThreads();
// Get all threads System.out.println("SystemThreadList: main(): printing individual thread info."); Thread[] allThreads = stl.getAllThreads();
if((allThreads == null) || (allThreads.length < 1)) { System.out.println("SystemThreadList: main(): allThreads is null or length < 1."); System.exit(1); }
// Print thread info Thread t = null; for(int i = 0; i < allThreads.length; i++) { t = allThreads[i]; System.out.println("Thread " + i + " = " + t.toString()); }
// Try to destroy root group (Should throw a ThreadIllegalStateException) //System.out.println("SystemThreadList: main(): trying to destroy root group. ;)"); //stl.destroyRootThreadGroup();
// Try to get threads with "Signal" in their name. System.out.println("SystemThreadList: main(): getting threads with \"Signal\" in their name."); List signalThreads = stl.getThreadsWithNameMatch("Signal"); if((signalThreads == null) || (signalThreads.size() < 1)) { System.out.println("... no signal threads found."); } else { for(int j = 0; j < signalThreads.size(); j++) { System.out.println("signalThreads[" + j + "] = " + ((Thread)signalThreads.get(j)).toString()); } }
System.out.println("SystemThreadList: main(): done."); } } // End of class: SystemThreadTest
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<%@ page info = "$Id: threads.jsp,v 1.4 2004/12/21 14:27:15 ronald Exp $" import = " java.net.InetAddress, java.util.Calendar, java.util.TimeZone " %> <%! class Group { JspWriter out; Group(JspWriter out) { this.out = out; } void print(ThreadGroup tg, String prefix) throws java.io.IOException { int i; out.println(prefix + "G " + tg.getName()); ThreadGroup[] tga = new ThreadGroup[tg.activeGroupCount()]; int nr = tg.enumerate(tga, false); for(i = 0; i < nr; i++) { this.print(tga[i], prefix + "\t"); } Thread[] ta = new Thread[tg.activeCount()]; nr = tg.enumerate(ta, false); String[] names = new String[nr]; for(i = 0; i < names.length; i++) { names[i] = ta[i].getName(); } java.util.Arrays.sort(names); for(i = 0; i < nr; i++) { out.println(prefix + "T " + names[i]); } } } %> <html> <head> <%@ include file="/pub/exec/baseDHTML.jspf" %> <!-- <%=getServletInfo()%> --> <title>Threads - <%=ServletUtils.getServerName(request)%></title> </head> <body> <% java.util.Date now = Calendar.getInstance(TimeZone.getTimeZone("Europe/Amsterdam")).getTime(); %> Server: <%=InetAddress.getLocalHost().toString()%><br/> Time: <%=now.toString()%><br/> <pre> <% Thread current = Thread.currentThread(); ThreadGroup tg = current.getThreadGroup(); while(tg.getParent() != null) { tg = tg.getParent(); } Group g = new Group(out); g.print(tg, ""); %> </pre> </body> </html>
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