What methods can be used to prevent or eliminate deadlock in a system?

A deadlock occurs when two or more threads are permanently waiting for each other to release resources. To prevent or resolve deadlocks, the following methods can be used:

• Avoid deadlocks: design the system so that threads do not acquire multiple resources simultaneously.
• Order resource acquisition: always acquire resources in the same order to avoid cyclic waiting.
• Use timeouts when acquiring locks: if a resource is unavailable for a certain period, release already acquired resources and retry.
• Use tryLock instead of lock: allows attempting to acquire a lock without blocking the thread, helping to avoid deadlocks.
• Detection and recovery: periodically check the system for deadlocks and take actions to resolve them (e.g., interrupt one of the threads).

Example of using tryLock in Java:

ReentrantLock lock1 = new ReentrantLock();
ReentrantLock lock2 = new ReentrantLock();

if(lock1.tryLock()) {
    try {
        if(lock2.tryLock()) {
            try {
                // work with resources
            } finally {
                lock2.unlock();
            }
        } else {
            // failed to acquire lock2, handle accordingly
        }
    } finally {
        lock1.unlock();
    }
}