Using continuations in high order languages such as Common Lisp is notvery efficient because they do not work close to the compiler . Other optionssuch as making an scheduler in C can be efficient when the sources of theinterpreter are available and they can be modified, otherwise, making aninterface with C using FFI causes an overhead, making it impossible toachive “lighweight”.To make an efficient implementation of lighweight threads in CommonLisp it is required to analyze the type of applications which will use thethreads. For example, for a Concurrent Constraint Programming (CCP)interpreter using Gecode, event driven programming seams very natural,but for the Omax system, it is not be appropriate.
How to Implement Lightweight Threads