go mutex example explain

tags: learning go programming

question

• in the example in go-mutex-basics, mutex and counter are two different and unrelated example, why does mutex.Lock/Unlock affect counter?

content

• they ARE different and separate variables
• mutex doesn’t directly affect counter
• they have no intrinsic connection to each other

Note

• a mutex has no intrinsic connection with the things it’s protecting.
• it’s only a way of communication between threads.
• it’s basically a flag variable that a thread checks before doing something.

how does mutex actually work?

• a Mutex doesn’t lock variables
  • a mutex has no knowledge of what’s the variable being protected
  • a mutex itself is just a variable
  • it’s a variable with two states, locked and unlocked
• when a go routine calls mutex.Lock(), it simply:
  • either occupies the lock if the lock is free
  • or blocks and waits until the lock is free
• it’s more like a way to “communicate” between go routines
  • one go routine uses mutex to tell other go routines whether they can proceed or not
• it’s a synchronization mechanism between go routines

up

• go-mutex-basics

down

• go-rwmutex

reference