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PODeadlocks and Synchronized methods
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copied!<p>I've found one of the code on Stack Overflow and I thought it is pretty similar to what I am facing but I still don't understand why this would enter a deadlock. The example was taken from <a href="https://stackoverflow.com/questions/217113/deadlock-in-java">Deadlock detection in Java</a>:</p> <pre><code>Class A { synchronized void methodA(B b) { b.last(); } synchronized void last() { System.out.println(“ Inside A.last()”); } } Class B { synchronized void methodB(A a) { a.last(); } synchronized void last() { System.out.println(“ Inside B.last()”); } } Class Deadlock implements Runnable { A a = new A(); B b = new B(); // Constructor Deadlock() { Thread t = new Thread(this); t.start(); a.methodA(b); } public void run() { b.methodB(a); } public static void main(String args[] ) { new Deadlock(); } } </code></pre> <p>In this case, when the Deadlock() constructor is called, it starts itself as a thread. When it does this, the run() method is invoked. It will call b.methodB(a), which then calls a.last() to just print out a statement. At the same time, a.methodA(b) would call b.last(). There is no cross dependencies on any object and they are not executing a method at a same time too. Even if they are, the synchronized keyword would queue them, wouldn't it? But how come this would occasionally enter a deadlock too? It is not all the time but it would sometimes enter a deadlock, which is quite unpredictable. What is it that causes this to go into a deadlock and workarounds?</p>

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