What are the main difficulties that may arise when implementing multithreading in a program?

The main challenges in implementing multithreading in a program include:

• Race conditions: when multiple threads simultaneously access and modify shared data, leading to unpredictable results.
• Deadlocks: a situation where two or more threads wait for each other, and none can continue.
• Synchronization issues: the need to properly use synchronization mechanisms (mutexes, semaphores, locks) to avoid errors and not degrade performance.
• Debugging complexity: errors in multithreaded code are often difficult to reproduce and trace.
• Thread lifecycle management: correct creation, start, suspension, and termination of threads.

Example of using a mutex in Android (Java):

private final Object lock = new Object();

public void incrementCounter() {
    synchronized(lock) {
        counter++;
    }
}