How to get stack trace of a thread

Question

I have a multithreaded application. Several messages are coming to the application and are processed in separated threads. For this I am using classes ThreadPoolExecutor and FutureTask from package java.util.concurrent.

Occasionally I have some deadlocks in the application. When a deadlock occurs I want to interrupt the blocking thread and I want to log the stack trace of this thread so that I can later resolve the deadlock.

Is there any way how can we find the stack trace of a thread outside of that thread in Java?

Answer 1

See here for how to generate stack traces, including how to do this programatically. From the console, Ctrl+Break will dump the stack traces to stdout. See also this SO question for more details.

Answer 2

You could log the stack traces of all thread from time to time (or before killing the process) from within your application. To do that use:

Map<Thread, StackTraceElement[]> m = Thread.getAllStackTraces();
for(Map.Entry<Thread,  StackTraceElement[]> e : m.entrySet()) {
    log(e.getKey().toString());
    for (StackTraceElement s : e.getValue()) {
        log("  " + s);
    }
}

When running nightly automated tests, sometimes some one of the test cases gets into a deadlock. I added a "TimeBomb" daemon thread that waits 30 minutes, and if then logs all stack traces as above.

Answer 3

I wasn't sure if you wish to obtain the stacktrace from within the same JVM or externally, but if you wish to obtain the stack trace with external tools, the following will help:

• The Java VisualVM tool can be used to connect to the running JVM, where the thread stack can be dumped. This is usually the preferred approach for most people using Java 6. Once VisualVM is launched, the thread dump of the process can be obtained by selecting the process in the Application tab. A Threads tab is now made available to view the threads in the running process, and in the same tab you'll find the "Thread Dump" button to extract the required information.
• The jstack utility within the JDK can also be used to produce thread stacktraces.

Answer 4

You use JStack. Here is a nice blog entry that details how to get stack traces.

Answer 5

Before entering the deadlock region, set a field like, thread = Thread.currentThread();

In your monitoring thread you can perform thread.getStackTrace(); to get the stack trace of that thread at any time.