The right thing is not to modify a global state once you have started all the threads. If you need to do that, use your own data structures. The case of getaddr

The right thing is not to modify a global state once you have started all the threads. If you need to do that, use your own data structures. The case of getaddrinfo - would need a copy of the entire env. in a thread safe manner, then return the result. That would pretty much apply to anything that uses env