replacement for GNU Pth using system threads

 nPth is a non-preemptive threads implementation using an API very
 similar to the one known from GNU Pth. It has been designed as a
 replacement of GNU Pth for non-ancient operating systems. In
 contrast to GNU Pth is based on the system's standard threads
 implementation. Thus nPth allows the use of libraries which are not
 compatible to GNU Pth.