Shared memory and shared variables
Shared memory and shared variables are huge topics in concurrent programming and the most common ways for UNIX threads to communicate with each other. The same principles apply to Go and goroutines, which is what this section is about. A mutex variable, which is the abbreviation for a mutual exclusion variable, is mainly used for thread synchronization and for protecting shared data when multiple writes or a write and a read can occur at the same time. A mutex works like a buffered channel with a capacity of one, which allows, at most, one goroutine to access a shared variable at any given time. This means that there is no way for two or more goroutines to be able to update that variable simultaneously. Go offers the sync.Mutex and sync.RWMutex data types.
A critical section of a concurrent program is the code that cannot be executed simultaneously by all processes, threads, or, in this case, goroutines. It is the code that needs to be protected...
