musl, pronounced like “mussel” or “muscle”, is a “libc”, an implementation of the standard library functionality described in the ISO C and POSIX standards, plus common extensions, intended for use on Linux-based systems. It is lightweight, fast, simple, free, and aims to be correct in the sense of standards-conformance and safety.
libpthread-stubs provides stub functions for pthreads as weak aliases for platforms on which libc does not provide these stubs. Linking to both libc and libpthread-stubs will always provide a full set of pthread stubs, allowing programs and libraries to portably use pthreads when linked to pthreads
... [More] and improve single-threaded performance when not linked to pthreads. [Less]