Always read the documentation of your libraries to see if they give any thread-safety assurances - if they don't mention thread-safety, assume they do not have

Always read the documentation of your libraries to see if they give any thread-safety assurances - if they don't mention thread-safety, assume they do not have it. Concurrency in general, is really hard: hard to express and hard to debug - none of the languages I know do it perfectly. However, I like Go's concurrency primitives & tooling the most. Javascript and Erlang are runners up - for the record, the languages I'm familiar with are Erlang, Go, Python, Java, Javascript and C. I wouldn't know where C# or Rust would fit.