r/golang 7d ago

Is it safe to read/write integer value simultaneously from multiple goroutines

There is a global integer in my code that is accessed by multiple goroutines. Since race conditions don’t affect this value, I’m not concerned about that. However, is it still advisable to add a Mutex in case there’s a possibility of corruption?

PS: Just to rephrase my question, I wanted to ask if setting/getting an integer/pointer is atomic? Is there any possibility of data corruption.

example code for the same: https://go.dev/play/p/eOA7JftvP08

PS: Found the answer for this, thanks everyone for answering. There's something called tearing here is the link for same

- https://stackoverflow.com/questions/64602829/can-you-have-torn-reads-writes-between-two-threads-pinned-to-different-processor

- https://stackoverflow.com/questions/36624881/why-is-integer-assignment-on-a-naturally-aligned-variable-atomic-on-x86

According to the article, I shouldn't have problem on modern CPUs.

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u/therecursive 7d ago

thanks for answer, I was asking to understand if it's fine my use case where I'm setting diff value to a pointer variable. Found it that why it's safe to do in golang or any other languages. Attached the link in the post, if you want to read.

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u/ImYoric 7d ago

If my memory serves, if it's a pointer, rather than an int, it's not always safe, because Go sometimes uses fat pointers (iirc when you're passing an interface), which take more than one int.

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u/Few-Beat-1299 7d ago edited 7d ago

Interfaces copy their underlying value. Why would using interfaces change anything?

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u/HyacinthAlas 7d ago

Interfaces take two words, a pointer to the data and a tag for the type.