Pthread mutex assertion error

Question

I\'m encountering the following error at unpredictable times in a linux-based (arm) communications application:

pthread_mutex_lock.c:82: __pthread_mutex_lock         


        

Answer 1

I have just fought my way through this one and thought it might help others. In my case the issue occured in a very simple method that locked the mutex, checked a shared variable and then returned. The method is an override of the base class which creates a worker thread.

The problem in this instance was that the base class was creating the thread in the constructor. The thread then started executing and the derived classes implementation of the method was called. Unfortunately the derived class had not yet completed constructing and the mutex in the derived class had uninitialised data as the mutex owner. This made it look like it was actually locked when it wasn't.

The solution is really simple. Add a protected method to the base class called StartThread(). This needs to be called in the derived classes constructor, not from the base class.