Abstract Processes vs. User-Level Threads in Scsh

The new version of scsh enables concurrent system programming with portable user-level threads. In scsh, threads behave like processes in many ways. Each thread receives its own set of process resources. Like Unix processes, forked threads can inherit resources from the parent thread. To store these resources scsh uses preserved thread fluids, a special kind of fluid variables. The paper gives a detailed description of an efficient implementation for thread-local process resources. Scsh also provides an interface to thefork system calls which avoids common pitfalls which arise with a userlevel thread system. Scsh contains a binding for fork that forks “only the current thread.”