How is a deadlock situation prevented in multithreaded systems?

Deadlock occurs when multiple threads wait for resources held by each other, and none can proceed. The following approaches are used to prevent deadlock:

1. Avoid cyclic dependencies: ensure that threads acquire resources in the same order.

2. Use timeouts: when attempting to acquire a lock with a timeout, a thread can give up and release already acquired resources.

3. Avoid nested locking: minimize the number of resources acquired simultaneously.

4. Detection and recovery algorithms: periodically check for deadlocks and interrupt or restart threads.

An example in Python using ordered lock acquisition:

import threading

lock_a = threading.Lock()
lock_b = threading.Lock()

# Thread 1
with lock_a:
    with lock_b:
        # critical section
        pass

# Thread 2
with lock_a:  # acquire lock_a before lock_b to prevent deadlock
    with lock_b:
        # critical section
        pass

Here, both threads acquire locks in the same order, preventing deadlock.