Sandboxing
PyPy's sandboxing is a working prototype for the idea of running untrusted user programs. Unlike other sandboxing approaches for Python, PyPy's does not try to limit language features considered “unsafe”. Instead we replace all calls to external libraries (C or platform) with a stub that communicates with an external process handling the policy.
To run the sandboxed process, get a sandboxed pypy-c and run:
pypy_interact.py pypy-c-sandbox
To read more about its features, go to our dev site.