Excellent article on thread safety and synchronisation from Herb Sutter.
A race condition occurs when two threads access the same shared variable concurrently, and at least one is a non-const operation (writer). Concurrent const operations are valid, and do not race with each other.
Guideline: A type should only be fully internally synchronized if and only if its purpose is to provide inter-thread communication (e.g., a message queue) or synchronization (e.g., a mutex).
musingstudio 