使变量更新对其他例程可见

Question

Golang newbie. In my program, a back group go-routine check environment and update a variable periodically. This variable is used in http handler method servers client request. So basically it is kind of single value cache has one updater and many consumers.

In language like Java, simply make this variable volatile could make sure updated value are visible to all those consumers. But since volatile is not an option in Go, what is the recommended solution here?

RW lock could work, but it seems overkill for this simple scenario.

Or this problem could be converted to communication via channel somehow?

Answer 1

If Java atomic variables would meet your needs in a Java app, then consider using Go's atomic memory primitives or the higher-level sync.Mutex / sync.RWMutex .

There's not enough information in the question to know if the application can be structured to make good use of channels.

Answer 2

I agree with @Volker that atomic functions should be used with care however for this simple scenario using atomic.Value is fairly straightforward:

var envVar atomic.Value
envVar.Store("")

...

// in write goroutine:
envVar.Store(os.Getenv("ENVVAR"))

...

// in read goroutine:
v := envVar.Load().(string)