Using wasmer from goroutines

[maxim-ge]

Summary

What is the safe way to use wasmer from multiple goroutines?

Additional details

If instance (result of wasm.NewInstance) is used by only one goroutine at any time - is it enough? The potential problem is that one goroutine might be executed by few threads.

[Hywan]

Since wasmerio/wasmer#807, I would say it is safe to use Instance in multiple threads yes, but I'm double-checking with some other members of the team.

[Hywan]

Some precisions:

• It is safe to use an instance from multiple threads (since Instance implements Send in the runtime, written in Rust),
• It isn't safe to re-enter the Instance from a Go function called as an imported function of the same instance (since Instance doesn't implement Sync in the runtime).

[Hywan]

https://golang.org/pkg/runtime/#LockOSThread can be useful for reentrance.

[maxim-ge]

Thanks a lot! Can I re-conclude a bit?

1. It is safe to use Instance from goroutines provided goroutines are synced (only one goroutine uses Instances at a time, but Instance can be safely re-used by another goroutine)
2. It is not safe to re-enter Instance from imported functions even provided (1) is satisfied

Correct?

[Hywan]

Instance can be used by any goroutines at a time, but cannot be sent to another goroutine.

[maxim-ge]

Ok, https://golang.org/pkg/runtime/#LockOSThread does the job, thank you very much!

[Hywan]

#84 (comment) isn't true. I didn't know that goroutines can run on a same thread or can be moved to another thread.