python-safethread is a large modification of CPython intended to provide safe, easy, and scalable concurrency mechanisms. It focuses on local concurrency, not distributed or parallel programs.
Note: As an implementation, python-safethread is dead. It is not worth the effort to continue rewriting CPython to have a true tracing GC.
However, the semantics presented are still viable and I intend to reuse them in future projects.
Some major features:
* Exceptions from threads propagate naturally and cause the program to shut down gracefully.
* No memory model is necessary. All mutable objects are safely contained with monitors (similar to Concurrent Pascal's monitors, but different from Java's monitors), or otherwise provide explicit semantics.
* Deadlocks are detected and broken automatically.
* Finalization is thread-safe (and uses a much simpler mechanism at a low-level.)
* Most existing single-threaded code will continue to be correct (and in good style) when used amongst threads. Some boilerplate may be necessary to share module and class objects between threads.
* The GIL is removed. Each additional thread should run at or near 100% throughput. However, the base (single-threaded) throughput is only around 60-65% that of normal CPython, so you'll need several threads for this to be worthwhile.
What little documentation there is exists at http://
Discussion may be done on the mailing list, http://