Какими методами можно предотвратить возникновение взаимных блокировок в многопоточной среде?

Deadlocks occur when two or more threads wait for each other, holding resources, and none can proceed. To prevent deadlocks in Java, the following methods are used:

1. Avoid nested locks — minimize the number of locks acquired simultaneously.

2. Always acquire locks in the same order — if multiple threads need to acquire several resources, the order should be consistent.

3. Use timeouts when acquiring locks — for example, the tryLock(long timeout, TimeUnit unit) method from java.util.concurrent.locks.Lock helps avoid infinite waiting.

4. Use high-level synchronization constructs — such as Semaphore, CountDownLatch, CyclicBarrier, which help manage threads without explicit locks.

5. Avoid holding locks when calling external methods — to prevent blocking resources for too long.

Example of correct lock acquisition order:

Object lock1 = new Object();
Object lock2 = new Object();

synchronized(lock1) {
    synchronized(lock2) {
        // work with resources
    }
}

If all threads follow this order, deadlock will not occur.