I have been interested in using Python to program simulated swarms of interacting agents. For this purpose, I have implemented what I call "microthreads" in Python, modifying Python's virtual machine, and maintaining a frame stack for each thread. I have successfully run 1500 threads simultaneously. Source code and some example usages are available at ftp://ftp.std.com/pub/wware/uthread.tgz for anybody interested in this. This is a pre-pre-thinking-about- alpha-some-day release, and probably buggy, but the examples run as expected. == - - - - - - - - - - - - - - - - - - - - - - - - Resistance is futile. Capacitance is efficacious. Will Ware email: wware @ world.std.com [Moderator's note: the following is taken from the package's README file.] ************************************************************************** Microthreads for Python Will Ware <wware@world.std.com> It would be nice to use Python for programs involving huge numbers of very light-weight threads. This would make it easy to simulate large swarms of interacting agents, which sounds like fun. Python functions are compiled to a bytecode, which runs on a virtual machine, defined in Python/ceval.c in the eval_code2 function. Python uses frame objects to administer information involved in nested function calls. In ceval.c, the frame stack is implicitly embedded in the C stack, because eval_code2 calls itself recursively when one Python function calls another. Microthreads are implemented with a modified version of the eval_code2 function. This version allows different threads to maintain different frame stacks explicitly. This version also executes a predetermined number of opcodes, whereas eval_code2 normally runs an infinite loop, terminating only when a function reaches either an error or a return statement. Two data structures have been defined. One is a thread object, which includes a frame stack, and also stacks for program counters and stack pointers. The other is a semaphore object, which provides an ability for threads to coordinate with one another. Using a semaphore it is possible to define a mailbox in Python, whereby one thread can send messages to another. The included example files demonstrate how threads and semaphores work, and how to implement a mailbox. ************************************************************************** <P><A HREF="ftp://ftp.std.com/pub/wware/">Python microthreads</A> - experimental implementation of interpreter-level threads using a modified Python byte code interpreter. (01-Aug-99) -- ----------- comp.lang.python.announce (moderated) ---------- Article Submission Address: python-announce@python.org Python Language Home Page: http://www.python.org/ Python Quick Help Index: http://www.python.org/Help.html ------------------------------------------------------------