title: Can different threads insert into a map if they always use different keys?
body: <p>I'm trying to design a message queue for an object. There is a set of X threads that can all send message (to be processed later) to this object. If I have a <code>std::map&lt;thread_id_t, message&gt;</code>, is this thread safe, assuming thread one only adds messages with a key of 1, thread 2 to key 2, etc..?</p>