Getting thread dump of JWS application

Question

Hi,
I know this was discussed a few times before, but I still have no solution for my problem.
I have a JWS GUI application that deadlocks sometimes (Windows 98). So I want to get the thread dump to analyze the deadlock. In Java Web Start I changed the java command from javaw.exe to java.exe, so I get a dos box. When I press CTRL-BREAK inside the dos box, I get the thread dump but because the dos box just shows a few lines I only get the last lines of the dump. Under Windows 98 I cannot resize the dos box.
Is there a way to redirect the output of the dos box to a file? Or is there another way to get the thread dump of a JWS application?
Thanks in advance
Markus

Answer 1

Here is 50% of the solution. To generate a thread dump programatically, you need to call JVM_DumpAllStacks through JNI. You need to link in "jvm.lib".
JNIEXPORT void JNICALL JVM_DumpAllStacks(JNIEnv *env, jclass unused);
JNIEXPORT void JNICALL Java_Services_generateThreadDump(JNIEnv *env, jobject thisObject) {
     // Produce a thread dump to VM standard out
     JVM_DumpAllStacks( env, NULL );
}Here is the java class that calls the JVM_DumpAllStacks method through JNI.
public class Services {
      * Send a message to the VM, forcing it to create a thread dump. The resulting
      * thread dump will be sent to stdout. Note that this is the VM's stdout, not
      * necessarily System.out.
     public static native void generateThreadDump();
}When you reach the point in your code that you want to generate a thread dump, close stdout and reopen it with the thread dump destination stream. Next, call the JNI method. This will send the thread dump to stdout.
     // Replace stdout with a file output stream
     System.out.close();
     System.setOut( new PrintStream( new FileOutputStream( "stdout.log" )));
     // Generate thread dump
     Services.generateThreadDump();Why is this only 50% of the solution ? Because this works beautifully for regular applications but it does NOT work for WebStart applications. Not sure what is happening here, but so far I have not managed to get any thread dump in a file from an application that has been fired up through WebStart. Note that I CAN get a thread dump in a file if I fire up the same code from the command line.