add lock for value operation.

[zhanglp92]

When I concurrent running program, has some wrong. I don‘t use metex with my code.
I think locks should be added here.

[metalmatze]

Is this still necessary when using atomic 🤔

[grobie]

No. client_golang is concurrency safe and uses the atomic package to reduce the footprint. Mutex are not only unnecessary here, they would incur a huge performance penalty.

Björn gave a talk explaining the design at the GopherCon 2015, here are the slides.

[beorn7]

The only concurrency issue I know of is #275 (for which I have a solution in my head, I just need to find time to write it down).

[zhanglp92]

If you do not use the lock, there will be concurrency issue.
eg: I concurrent implementation of the program.

func test() {
gauge.Inc()
defer gauge.Dec()
}

[beorn7]

Could you provide the full code to replicate the problem? The above is not sufficient to do that.