How to detect deadlock ? Timeout in synchronized block?

Question

I’m debugging a Java application that runs several threads. After a while of watching the log it seems that one of those threads is not running anymore. My guess is that the thread is waiting for a lock that is never released (the last output is before calling a synchronized method).

Can I configure a timeout to the thread; a sort of “wait for this lock but if it not available after 10 seconds don’t wait anymore!”

Answer 1

You can use a java.util.concurrent.Lock instead of the intrinsic Object locks. RentrantLock without fair ordering has the same basic behaviour and semantics as an intrinsic lock. There is a method tryLock that takes a timeout parameter:

Lock lock = ...;
if (lock.tryLock(10L, TimeUnit.SECONDS)) {
    try {
        // manipulate protected state
    } finally {
        lock.unlock();
    }
} else {
      // perform alternative actions
}