Deadlock is a situation where two or more threads are blocked waiting for each other to release the locks they hold, resulting in a deadlock state where none of the threads can make progress. Here’s an example Java program that creates a deadlock:
public class DeadlockExample {
private static final Object lock1 = new Object();
private static final Object lock2 = new Object();
public static void main(String[] args) {
Thread t1 = new Thread(() -> {
synchronized (lock1) {
System.out.println("Thread 1 acquired lock 1");
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (lock2) {
System.out.println("Thread 1 acquired lock 2");
}
}
});
Thread t2 = new Thread(() -> {
synchronized (lock2) {
System.out.println("Thread 2 acquired lock 2");
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (lock1) {
System.out.println("Thread 2 acquired lock 1");
}
}
});
t1.start();
t2.start();
}
}
In this example, we have two threads t1 and t2, and two locks lock1 and lock2. Thread t1 acquires lock1 and then waits for lock2, while thread t2 acquires lock2 and then waits for lock1. This creates a deadlock situation, where neither thread can proceed and the program hangs indefinitely.
How to avoid deadlocks:
it’s important to ensure that threads always acquire locks in the same order, and to avoid holding locks for long periods of time. Additionally, it’s important to minimize the number of locks used in a program to reduce the chances of creating a deadlock.
