» For other uses of the term, see Reentrant (disambiguation)A computer program or routine is described as reentrant if it can be safely executed concurrently; that is, the routine can be re-entered while it's already running. To be reentrant, a function must: Hold no static (global) non-constant data. Must not return the address to static (global) non-constant data. Must work only on the data provided to it by the caller. Must not rely on locks to singleton resources. Must not call non-r… (More on Reentrant)