What are some examples of deadlocks in Python?

What are some examples of deadlocks in Python?

Deadlocks in Python occur when two or more threads are blocked forever, each waiting for the other to release a resource. A common example is when two threads try to acquire locks in different orders.

Can you provide a code example of a deadlock?

Sure! Here's a simple example:

import threading

lock1 = threading.Lock()
lock2 = threading.Lock()

def thread1():
    lock1.acquire()
    print('Thread 1 acquired lock 1')
    lock2.acquire()
    print('Thread 1 acquired lock 2')
    lock2.release()
    lock1.release()


def thread2():
    lock2.acquire()
    print('Thread 2 acquired lock 2')
    lock1.acquire()
    print('Thread 2 acquired lock 1')
    lock1.release()
    lock2.release()

thread_a = threading.Thread(target=thread1)
thread_b = threading.Thread(target=thread2)

thread_a.start()
thread_b.start()

thread_a.join()
thread_b.join()

This code can lead to a deadlock if both threads try to acquire the locks simultaneously.

How can I avoid deadlocks in my code?

To avoid deadlocks, you can use a timeout when trying to acquire locks, ensure a consistent order of lock acquisition, or use higher-level abstractions like threading.Condition or threading.Semaphore.