Guidelines

What happens if a mutex is not unlocked?

What happens if a mutex is not unlocked?

If you don’t, then a typical mutex is held in process memory and will simply cease to exist along with anything that might have access to it when the process terminates.

Do you have to unlock a mutex?

mutex::unlock The mutex must be locked by the current thread of execution, otherwise, the behavior is undefined. This operation synchronizes-with (as defined in std::memory_order) any subsequent lock operation that obtains ownership of the same mutex.

How do you bypass mutex?

Force unlock a mutex that was locked by a different thread

  1. Abandon the mutex and create a new one. This is the undesirable option as it creates a memory leak.
  2. Close all network ports and restart the server.
  3. Go into the kernel internals and release the mutex there bypassing the error checking.
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How do I know if mutex is locked?

std::mutex::try_lock If the mutex is currently locked by another thread, the function fails and returns false , without blocking (the calling thread continues its execution). If the mutex is currently locked by the same thread calling this function, it produces a deadlock (with undefined behavior).

Can Pthread_mutex_unlock block?

Yes, it is a blocking call and will block until it gets the lock. Normally, pthread_mutex_lock cannot return until it acquires the lock, even if this means that it never returns (deadlock).

What is Pthread_join in C?

DESCRIPTION. The pthread_join() function shall suspend execution of the calling thread until the target thread terminates, unless the target thread has already terminated.

Can another thread unlock mutex?

If a thread attempts to unlock a mutex that it has not locked or a mutex which is unlocked, undefined behavior results. As user562734’s answer says, the answer is no – you cannot unlock a thread that was locked by another thread.

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What is the difference between unique_lock and Lock_guard?

A lock_guard always holds a lock from its construction to its destruction. A unique_lock can be created without immediately locking, can unlock at any point in its existence, and can transfer ownership of the lock from one instance to another.

What is mutex name in launch4j?

If you chose a Mutex, you allow only one instance of your application. You can chose a random Mutex name, example: abcMutex0. Without Mutex: With Mutex: If you get the error Enter Mutex Name? , you may have tick “Allow only a single instance of the application” but you haven’t enter a Mutex name.

Can a thread lock a mutex twice?

To solve your issue, you can use std::recursive_mutex , which can be locked/unlocked multiple times from the same thread.