flamelens

flamelens is an interactive flamegraph viewer in the terminal.

What is it?

Flamegraph tools such as FlameGraph and inferno process output from various profiling tools and generate intermediate data in the "folded" format ready for flamegraph plotting. Instead of plotting the flamegraph as an SVG file, flamelens takes the folded stacks data and generate an interactive flamegraph in the terminal.

No more hauling SVG files and opening a browser just to have a quick look at the profiling result!

Usage

Run flamelens with the filename of the profiling data in the form of "folded stacks":

flamelens <folded-stacks-filename>

You can also pipe data directly to flamelens without providing a filename.

cargo-flamegraph

You can use flamelens as the viewer of cargo flamegraph this way:

cargo flamegraph --post-process 'flamelens --echo' [other cargo flamegraph arguments]

The --echo flag ensures that the flamegraph SVG file is also generated by cargo flamegraph on exit.

Viewing perf data

If have a perf.data file generated by perf (e.g. by using cargo flamegraph to profile your program in Linux), you can visualize it in flamelens this way with the help of inferno:

perf script -i perf.data | inferno-collapse-perf | flamelens

See inferno on generating folded stacks data from profiling data of different formats.

Python

Display a live flamegraph of a running Python program using py-spy as the profiler:

flamelens --pid <pid-of-python-program>

This requires enabling the python feature when installing.

Key bindings

Installation

If you have Rust installed, flamelens is available on crates.io and you can install it using:

cargo install flamelens --locked

If you want the live flamegraph functionality, install with the --all-features option:

cargo install flamelens --locked --all-features

Alternatively, build and install from source after cloning this repo:

cargo install --path $(pwd) --locked