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POWhat keeps java processes alive after jar execution?
 

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  1. POWhat keeps java processes alive after jar execution?
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    <p>I have a java jar file which I am executing from the windows command prompt. The code finishes normally (i.e. does what it is supposed to) but the java process continues to run. The application is single threaded. I need to hit Ctrl-c to stop the process after the code completes to get the command prompt back. </p> <p>I assume that I could put a <code>System.exit(0)</code> at the end of my main method which would presumably fix this, but I was under the impression that it wasn't necessary. Under what conditions are java processes kept alive at the end of execution? Here's the shell of my main method:</p> <pre><code>public static void main(String[] args) { try { //application code here Logger.log("Now finished"); } catch (SomeExceptoin e) { Logger.error("Some error occured"); } } </code></pre> <p>Where the logger is my own incredibly basic static class which just dumps messages to <code>System.out.println()</code>. "Now finished" appears in the console, but the process continues to run. Any ideas? </p> <p>EDIT: As requested, here's the logger code in all its glory (I did warn you :)</p> <pre><code>public class Logger { public static void logInfo(String logMessage) { System.out.println(timestamp() + logMessage); } private static String timestamp() { SimpleDateFormat formatter = new SimpleDateFormat("yyyy.MM.dd hh:mm:ss"); String timestamp = "[" + formatter.format(new Date()) + "] "; return timestamp; } } </code></pre> <p>EDIT EDIT: I put a finally block onto my try above with the thread dump code from the link in instanceofTom's answer. Here's the output:</p> <p>... [2010.11.18 11:22:57] Output complete. All processing now finished. </p> <hr> <p>Thread name: Reference Handler java.lang.Object.wait(Native Method) java.lang.Object.wait(Object.java:485) java.lang.ref.Reference$ReferenceHandler.run(Reference.java:116) </p> <hr> <p>Thread name: Finalizer java.lang.Object.wait(Native Method) java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:116) java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:132) java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:159) </p> <hr> <p>Thread name: Signal Dispatcher </p> <hr> <p>Thread name: Attach Listener </p> <hr> <p>Thread name: Java2D Disposer java.lang.Object.wait(Native Method) java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:116) java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:132) sun.java2d.Disposer.run(Disposer.java:125) java.lang.Thread.run(Thread.java:619) </p> <hr> <p>Thread name: main java.lang.Thread.getStackTrace(Thread.java:1436) com.my.code.WorkloadManager.visit(WorkloadManager.java:124) com.my.code.WorkloadManager.visit(WorkloadManager.java:138) com.my.code.WorkloadManager.main(WorkloadManager.java:71) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) java.lang.reflect.Method.invoke(Method.java:597) org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:56) </p> <hr> <p>Thread name: com.google.inject.internal.Finalizer java.lang.Object.wait(Native Method) java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:116) java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:132) com.google.inject.internal.Finalizer.run(Finalizer.java:114) </p> <hr> <p>Thread name: AWT-Windows sun.awt.windows.WToolkit.eventLoop(Native Method) sun.awt.windows.WToolkit.run(WToolkit.java:291) java.lang.Thread.run(Thread.java:619) </p> <hr> <p>Thread name: EventQueueMonitor-ComponentEvtDispatch java.lang.Object.wait(Native Method) java.lang.Object.wait(Object.java:485) com.sun.java.accessibility.util.ComponentEvtDispatchThread.run(EventQueueMonitor.java:616) <strong><em>*</em>**<em>*</em>**<em>*</em>**<em>*</em>**<em>*</em>**<em>*</em></strong> Thread name: Reference Handler java.lang.Object.wait(Native Method) java.lang.Object.wait(Object.java:485) java.lang.ref.Reference$ReferenceHandler.run(Reference.java:116) </p> <hr> <p>Thread name: Finalizer java.lang.Object.wait(Native Method) java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:116) java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:132) java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:159) </p> <hr> <p>Thread name: Signal Dispatcher </p> <hr> <p>Thread name: Attach Listener </p> <hr> <p>Thread name: Java2D Disposer java.lang.Object.wait(Native Method) java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:116) java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:132) sun.java2d.Disposer.run(Disposer.java:125) java.lang.Thread.run(Thread.java:619) </p> <hr> <p>Thread name: main java.lang.Thread.getStackTrace(Thread.java:1436) com.my.code.WorkloadManager.visit(WorkloadManager.java:124) com.my.code.WorkloadManager.visit(WorkloadManager.java:138) com.my.code.WorkloadManager.main(WorkloadManager.java:71) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) java.lang.reflect.Method.invoke(Method.java:597) org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:56) </p> <hr> <p>Thread name: com.google.inject.internal.Finalizer java.lang.Object.wait(Native Method) java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:116) java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:132) com.google.inject.internal.Finalizer.run(Finalizer.java:114) </p> <hr> <p>Thread name: AWT-Windows sun.awt.windows.WToolkit.eventLoop(Native Method) sun.awt.windows.WToolkit.run(WToolkit.java:291) java.lang.Thread.run(Thread.java:619) </p> <hr> <p>Thread name: EventQueueMonitor-ComponentEvtDispatch java.lang.Object.wait(Native Method) java.lang.Object.wait(Object.java:485) com.sun.java.accessibility.util.ComponentEvtDispatchThread.run(EventQueueMonitor.java:616) </p>
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    1. USChris Knight
    1. USChris Knight
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    1. CODoes the java program call Runtime.exec() at all?
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      1. USizb
    2. COI would perhaps post the logger code also. Somehow an orphaned thread has to be persisting. I know of no other way for this to occur.
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      1. POWhat keeps java processes alive after jar execution?
      1. USaepryus
    3. COA frequent cause is additional, non-daemon threads. Although your code is single-threaded, are you positive that none of the things you're calling are creating non-daemon threads?
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      1. POWhat keeps java processes alive after jar execution?
      1. USAndy Thomas
 

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