mutex implementation

1. How is mutex implemented?
2. How do I use mutex between processes?
3. What defines a mutex?
4. What is a mutex in C++?
5. Why is mutex used?
6. Why is mutex needed?
7. What is difference between semaphore and mutex?
8. What is the purpose of synchronizing processes?
9. Can processes use locks?
10. When would you use a mutex lock?
11. How does mutex lock work?
12. What happens when mutex is locked?

How is mutex implemented?

A mutex preferably runs in the kernel of the operating system while keeping the amount of code around it as short as possible, so it can avoid being cut-off while task-switching to another process. ... If the mutex is free, it sets the mutex and executes the code, only to release the mutex when done.

How do I use mutex between processes?

For inter-process synchronization, a mutex needs to be allo- cated in memory shared between these processes. Since the memory for such a mutex must be allocated dynamically, the mutex needs to be explicitly initialized using mutex_init(). It is quite possible to use a process-shared mutex.

What defines a mutex?

In computer programming, a mutex (mutual exclusion object) is a program object that is created so that multiple program thread can take turns sharing the same resource, such as access to a file.

What is a mutex in C++?

Mutex class. A mutex is a lockable object that is designed to signal when critical sections of code need exclusive access, preventing other threads with the same protection from executing concurrently and access the same memory locations.

Why is mutex used?

Mutex or Mutual Exclusion Object is used to give access to a resource to only one process at a time. The mutex object allows all the processes to use the same resource but at a time, only one process is allowed to use the resource. Mutex uses the lock-based technique to handle the critical section problem.

Why is mutex needed?

It ensures that only one thread is executing a key piece of code at a time, which in turns limits access to a data structure. It ensures that the both threads have a full and proper view of that memory irrespective of any CPU reordering. The mutex is an absolute necessity when doing concurrent programming.

What is difference between semaphore and mutex?

KEY DIFFERENCE

Semaphore supports wait and signal operations modification, whereas Mutex is only modified by the process that may request or release a resource. Semaphore value is modified using wait () and signal () operations, on the other hand, Mutex operations are locked or unlocked.

What is the purpose of synchronizing processes?

The main purpose of synchronization is the sharing of resources without interference using mutual exclusion. The other purpose is the coordination of the process interactions in an operating system. Semaphores and monitors are the most powerful and most commonly used mechanisms to solve synchronization problems.

Can processes use locks?

Filesystem-level locks (on files or parts of files) can also used to coordinate between multiple processes. ... Processes can share memory. (And in fact most of them do, if only in a read-only fashion - pages containing shared library code are shared between processes.

When would you use a mutex lock?

Mutex: Use a mutex when you (thread) want to execute code that should not be executed by any other thread at the same time. Mutex 'down' happens in one thread and mutex 'up' must happen in the same thread later on.

How does mutex lock work?

The idea behind mutexes is to only allow one thread access to a section of memory at any one time. If one thread locks the mutex, any other lock attempts will block until the first one unlocks. ... To lock itself, the mutex has to set a bit somewhere that says that it is locked.

What happens when mutex is locked?

If the mutex is currently locked by another thread, execution of the calling thread is blocked until unlocked by the other thread (other non-locked threads continue their execution). If the mutex is currently locked by the same thread calling this function, it produces a deadlock (with undefined behavior).