In computer science, a thread typically refers to a sequence of software code the computer and its CPU must execute. In programming, a thread is the smallest series of related instructions involved in a process, which can involve many threads.

In multi-threaded computer programming, a function is thread-safe when it can be invoked or accessed concurrently by multiple threads without causing unexpected behavior, race conditions, or data corruption.

A procedure is thread safe when it is logically correct when executed simultaneously by several threads. At a practical level, it is convenient to recognize three levels of safety.

The Thread-safe Interface pattern is related to the Decora- tor pattern [2], which extends an object transparently by dy- namically attaching additional responsibilities. The intent of the Thread-safe Interface pattern is similar, in that it attaches robust and efficient locking strategies to thread-safe compo- nents.