bloomberg/pystack

PyStack is a debugging tool that prints stack traces from running Python processes or Python core dump files.

PyStack solves the problem of understanding what a Python process is doing or was doing when it crashed, without requiring manual interpretation of CPython internals. It attaches to a running process or reads a core dump file and extracts stack frame information. The tool works by reading process memory and can optionally show native C/C++/Rust function calls interleaved with Python frames, automatically demangle symbols, include inlined functions when debug information is available, and display local variable values in Python stack frames.

The tool is designed for Linux systems and suits developers who need rapid diagnosis of hanging or crashed Python processes. It is particularly valuable for analyzing optimized Python binaries that lack symbols or debug information, and it tolerates memory corruption well, often reconstructing stacks even when a process crashed due to corruption. PyStack can analyze core files significantly faster than general-purpose tools like GDB. The tool is safe to use on running processes, either with minimal impact through non-pausing analysis or with brief attachment that does not modify memory or execute code. It requires only the Python interpreter and standard Linux libraries, with no external tool dependencies.

The project maintains active test coverage through continuous integration workflows. Development follows a consistent code style standard. The tool supports multiple Python implementations and versions across the PyPI ecosystem.