What are the guidelines to follow while using mutex lock?

What are the guidelines to follow while using mutex lock?

Do not reinitialize or destroy a mutex lock while other threads are using the mutex. Program failure results if either action is not done correctly. If a mutex is reinitialized or destroyed, the application must be sure the mutex is not currently in use.

How does mutex know to lock?

Mutexes guarantee code is accessed by only one thread at a time, not data. But you can have the data protected by encapsulating it: put the protected resource in private fields and make get/set accessors use the mutex to coordinate access.

Which semaphore is almost same as mutex lock?

A Mutex is different than a semaphore as it is a locking mechanism while a semaphore is a signalling mechanism. A binary semaphore can be used as a Mutex but a Mutex can never be used as a semaphore.

What happens when you call mutex.lock ( )?

When you call mutex.lock (), your thread stalls in lock () and makes a lock request to the OS. When the OS detects that the mutex was released from a thread, it merely gives it to you, and lock () returns – the mutex is now yours and only yours.

What’s the best way to avoid mutex deadlock?

pthread_mutex_unlock(&m2); The best way to avoid this problem is to make sure that whenever threads lock multiple mutexes, they do so in the same order. When locks are always taken in a prescribed order, deadlock should not occur. This technique is known as lock hierarchies: order the mutexes by logically assigning numbers to them.

How to use mutex lock examples for Linux thread sync?

Suppose one thread has locked a region of code using mutex and is executing that piece of code. Now if scheduler decides to do a context switch, then all the other threads which are ready to execute the same region are unblocked.

When do you need to use a mutex?

Mutexes are useful in situations where you need to enforce exclusive access to a resource accross multiple processes, where a regular lock won’t help since it only works accross threads. Mutex: Mutex stands for Mut ual Ex clusion.

How to use mutex lock in multithreaded programming?

The increment_count () function uses the mutex lock simply to ensure an atomic update of the shared variable. The get_count () function uses the mutex lock to guarantee that the 64-bit quantity count is read atomically. On a 32-bit architecture, a long long is really two 32-bit quantities.

What happens if you fail to unlock the mutex?

If you fail to Unlock () on an error, then it is possible that your application will go into a deadlock as other goroutines will be unable to attain the lock on the mutex! One example to keep in mind when developing with mutexes is that the Lock () method will block until it attains the lock.

How to avoid deadlock when Locking multiple mutexes?

The best way to avoid this problem is to make sure that whenever threads lock multiple mutexes, they do so in the same order. When locks are always taken in a prescribed order, deadlock should not occur.

Where is the mutex in the main function?

A mutex is initialized in the beginning of the main function. The same mutex is locked in the ‘trythis ()’ function while using the shared resource ‘counter’. At the end of the function ‘trythis ()’ the same mutex is unlocked.