A mutex, short for mutual exclusion, is a synchronization primitive used in concurrent programming to prevent multiple threads from accessing a shared resource simultaneously. This ensures that only one thread can execute a critical section of code at a time, thereby avoiding race conditions and ensuring data consistency.
Key Characteristics of a Mutex
Ownership: A mutex has the concept of ownership, meaning that only the thread that has locked the mutex can unlock it. This helps in preventing accidental releases by other threads[1][2][3][4].
Mutual Exclusion: The primary purpose of a mutex is to provide mutual exclusion. When a thread locks a mutex, other threads attempting to lock it will be blocked until the mutex is unlocked[1][2][3][5].
Kernel-Level Implementation: Mutexes often involve kernel-level operations, which can result in system calls. This is particularly true in operating systems like UNIX, where mutexes are implemented via pthread_mutex_t[4].
Priority Inversion Handling: Some mutex implementations include mechanisms to handle priority inversion, where a lower-priority thread holds a mutex needed by a higher-priority thread. Priority inheritance is one such mechanism[3].
Deadlock Prevention: Proper use of mutexes can help prevent deadlocks, although poor design can still lead to deadlock situations. For instance, acquiring multiple locks in a consistent order can help avoid deadlocks[5].
Example Use Cases
Shared Counters: In a multithreaded program, a mutex can be used to protect a shared counter variable, ensuring that only one thread can update the counter at a time[2][7].
Resource Management: Mutexes are used to manage access to shared resources ...
