py-spy

py-spy is a sampling profiler for Python programs. It shows where a program spends its time without restarting it or modifying its code, by attaching to a running process or launching a new one.

It can record flame graphs, display a live top-like view of the busiest functions, or dump the current call stack of every thread, which helps with hung programs. Because it is written in Rust and runs outside the profiled process, its overhead is very low and it can be used on production code.

py-spy runs on Linux, macOS, Windows and FreeBSD and supports CPython 2.3–2.7 and 3.3 onwards. It is installed with pip and is free and open source under the MIT licence.