CODEWITHSUNDEEP
javamultithreadingerror-handling
prilia
prilia

Reputation: 1016

Java multithreading errors handling

I have one main thread it has created many workers, every worker is a thread.

How can I get errors from the workers in main thread if there was an Exception in some worker or worker cannot successfully ended ?

How to send error before the worker thread dead ?

Upvotes: 7

Views: 2905

Answers (4)

Ravindra babu
Ravindra babu

Reputation: 38910

Use ExecutorService or ThreadPoolExecutor

You can catch Exceptions in three ways

  1. Future.get()
  2. Wrap entire run() or call() method in try{}catch{}Exceptoion{} blocks
  3. Override afterExecute method of ThreadPoolExecutor

Refer to below SE question for more details:

Handling Exceptions for ThreadPoolExecutor

Upvotes: 1

Ankur Shanbhag
Ankur Shanbhag

Reputation: 7804

One way to achieve this is using signal passing in threads. Signal passing is used extensively, when you need threads to communicate between each other. Simple way to achieve this could be to access shared objects between threads and monitor the value of the object(indication of a signal). You can assign some value to the object indicating failure(in form of a signal) so that other threads can take appropriate actions.
Using signals, you can not only passing failure signals but various other status signals as well by setting appropriate value to a shared object (say Enum with different values indicating state of the thread).
Refer this link for more details :http://tutorials.jenkov.com/java-concurrency/thread-signaling.html

Upvotes: 0

Brian Agnew
Brian Agnew

Reputation: 272217

If you use the java.util.concurrent Executor frameworks and generate a Future from each submitted worker, then calling get() on the Future will either give you the worker's result, or the exception thrown/caught within that worker.

Upvotes: 4

Evgeniy Dorofeev
Evgeniy Dorofeev

Reputation: 135992

You can set global UncaughtExceptionHandler which will intercept all uncaught Exceptions in all threads

Thread.setDefaultUncaughtExceptionHandler(new UncaughtExceptionHandler() {
    @Override
    public void uncaughtException(Thread t, Throwable e) {
        ...
    }
});

Upvotes: 2

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