go mutex basics

tags: learning go programming

content

• Mutex: mutual exclusion
  • make sure at any given time, there’s only one go routine that’s accessing a variable to avoid conflicts
• achieve by Lock and Unlock variables

Note

mutex is a specific kind of locks

usage

• firstly, we need to create some variable that will be shared across different go routines, and a mutex to protect the shared resource:

var mutex sync.Mutex
counter := 0

• then we need to lock and unlock the mutex

increment := func(value *int) {
 mutex.Lock()
 defer mutex.Unlock()
 fmt.Println("im in go routine")
 *value++
 fmt.Println(*value)
}

• if we trigger increment in parallel

for range 10 {
 go increment(&counter)
}

• the result from fmt.Println in go routines:

  • will always be from 1 to 10, in order
  • "im in go routine" is printed before counter

• if there’s no mutex like shown below:

  • counter’s value printed out might not be in order
  • all "im in go routine"s are printed out all at once

increment := func(value *int) {
 fmt.Println("im in go routine")
 *value++
 fmt.Println(*value)
}

up

• go-routine-basics

down

• go-mutex-example-explain

reference