A New Safe External Debugger Interface for CPython

Learn about PEP 768, a groundbreaking proposal for Python 3.14 that introduces a safe, zero-overhead debugging interface to CPython in this 45-minute conference talk from EuroPython 2025. Discover the unique challenges Python developers face when trying to debug live production applications without stopping them, and understand why current debugging tools resort to unsafe methods that can crash interpreters and corrupt memory. Explore how PEP 768 revolutionizes Python debugging by introducing a cooperative debugging protocol that works harmoniously with the interpreter rather than against it. Gain insights into the technical implementation details of this zero-overhead solution, including how it enables safe debugging through interpreter cooperation and supports real-world applications like live process attachment for pdb. Examine the security considerations and safeguards built into this new debugging interface, and understand why attaching debuggers to Python processes presents such unique technical challenges compared to languages like C/C++. This presentation is particularly valuable for tool developers, system administrators, and anyone interested in Python internals or advanced debugging techniques, providing a comprehensive understanding of both the problems with current debugging approaches and the elegant solutions offered by PEP 768.