Correct.
a := make(map[int]string)
b := a
means that b and a point to the same map.
> Do you know any way in go to copy a map? Or the only way to do it is to
use json Marshal and Unmarshal?
That is called a "deep copy" and there are third party libraries for this.
But if you think you need it - just to access a map safely - then almost
certainly you are Doing It Wrong™.
One option is to use sync.Map, which is safe for concurrent access.
Better: protect your map properly against concurrent access. See
"Rethinking Classical Concurrency Patterns" by Bryan C. Mills - although if
you're not familiar with traditional approaches to concurrency, you may
find this hard to understand (it's worth the effort though)
https://www.youtube.com/watch?v=5zXAHh5tJqQ
One of the patterns which comes out of this video is to use a 1-element
channel as a way to hold a protected value. Every time you want to use
this value, you pop it out of the channel, use it, and then push it back in
(without keeping a copy). This gives you the same sort of protection as a
mutex, but cleaner and simpler.
Here is an example: two goroutines both concurrently updating the same map.
https://go.dev/play/p/nY3ujWh3Mfj
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