How to define threadsafe?

Question

Threadsafe is a term that is thrown around documentation, however there is seldom an explanation of what it means, especially in a language that is understandable to someone learning threading for the first time.

So how do you explain Threadsafe code to someone new to threading? My ideas for options are the moment are:

• Do you use a list of what makes code thread safe vs. thread unsafe
• The book definition
• A useful metaphor

Answer 1

Eric Lippert says:

When I'm asked "is this code thread safe?" I always have to push back and ask "what are the exact threading scenarios you are concerned about?" and "exactly what is correct behaviour of the object in every one of those scenarios?".

It is unhelpful to say that code is "thread safe" without somehow communicating what undesirable behaviors the utilized thread safety mechanisms do and do not prevent.