Mutex and binary semaphore are synchronization service providers that can access different resources. One is a locking system, whereas the other acts as a signal provider to ease many equational processes.
They are both very different depending on the type of mechanism that each uses to solve problems. They also differ on ownership type, as it decides the proper functioning of both.
Mutex vs Binary Semaphore
The main difference between mutex and binary semaphore is that a mutex is an exclusion object that uses a locking mechanism that ensures that only one single thread can use the mutex at a given time. On the other hand, a binary semaphore is a synchronization service provider that makes use of a signaling mechanism to ensure that more than one thread is used at a given time.
Mutex functions are the mechanisms laid down by a locking system. Only a single thread can be allowed to access the mutex service at a time, and after it is accessed, they can exit the mutex only after passing a position called the critical section. Because it is a single thread system, it is much more organized and easy to find in the software.
A binary semaphore works on the rules laid down by a signaling mechanism. At one time, many threads can function as a binary semaphore giving more privileges to the one that comes in later if it has a greater priority than the current thread that is in the semaphore. Because many different threads are using the binary semaphore at one time, there are chances of it being confused with one another, and it would also be harder to find.
Comparison Table Between Mutex and Binary Semaphore
| Parameters of Comparison | Mutex | Binary Semaphore |
| Full Form | Mutual Exclusion | None, it is binary semaphore itself |
| Mechanism | Locking | Signaling |
| Number of Threads | One | Many |
| Owners | Yes | None |
| Ease of Use | No | Yes |
What is Mutex?
A mutex is a short form of the expanded word “mutual exclusion”.
Mutual exclusion refers to an object that uses the locking mechanism as the operating unit.
It means that the functions provided by mutex are only usable if the locking mechanism is downloaded properly and updated to the latest version.
For any thread to release a mutex acquired through the locking system, it has to pass through a section of the synchronizing software called the critical section.
If the thread has not passed the critical section, then no mutex is released.
It leads to a useless program.
Mutex works depending on a locking system, yet all modifications are made to the thread even if the software is locked.
In simple terms, it means that values can be altered even if the system is not locked.
A feature of mutexes is that only a single thread can access the mutex and lock itself in the locking system.
Mutex is among those synchronizing software that allows an owner to be the final control unit.
The owner has the right to undo a lock that is blocking the transfer of resources and can also release the locks on threads.
Mutex is slow when compared to other synchronizing software. It is because the threads that are released at a time are those that have passed the critical section.
For users with a single instance, it would be better to use mutex.
It is because it is a single thread operator.
What is Binary Semaphore?
Binary semaphore functions according to the rules laid out by the mechanisms present in the signaling system.
For signaling software, it means that whichever thread has reached the priority status as required by binary semaphore can be accepted and released.
An advantage of the binary semaphore is that it can handle more than one thread at a time.
It is an added advantage as not every synchronizing software can pass and lock multiple threads in one go.
But, at times, this multiple thread rule could turn out to be disastrous as it can easily create a disordered storage unit that has to put in extra work to keep tabs on all the threads it gets.
No owner is needed for the binary semaphore to lock onto a specific thread.
It makes the whole process easy as it would automatically lock the high-priority thread with no effort needed.
The usage and installation of both mutex and binary semaphore can be decided upon by the time taken to process the thread, whether it be individually or simultaneously.
Another deciding factor is the organization of the storage unit.
The storage of mutexes is naturally expected to be proper and civil because mutexes allow a single thread lock at a time.
But binary semaphore has highly disorganized storage because many threads come in at the same time.
Even the ownership provides a bit of insight on the number of installations that each software gets every year.
The presence of an owner slows down the process of locking, so it is better to not have one.
References
- https://link.springer.com/chapter/10.1007/978-3-642-15291-7_2
- https://dl.acm.org/doi/pdf/10.1145/43914.43919