I am not sure how the parent comment has received so many upvotes. OP has some fundamental misunderstanding of mutexes and the purpose of async io. Locking pr

I am not sure how the parent comment has received so many upvotes. OP has some fundamental misunderstanding of mutexes and the purpose of async io. Locking primitives are completely unnecessary in any single threaded program. Also mutexes in C or otherwise are way older than 1990. They go back to the 1950s. When your program is single threaded, a simple boolean flag variable can act as a mutex, you don't need a mutex primitive for this. Mutexes are for situations where flag variables can change state between your instructions to check and set a flag. This can only happen in multithreaded or interrupt driven code. Infact, the entire purpose of async programming is to stop the use of mutexes and multiple threads to perform concurrent io, which is something that can be performed by a single thread. This is the foundational premise of nodejs.