eio-trace can be used to record and display traces of programs using the Eio library (requires Eio 0.14 or later).
To install eio-trace:
git clone --recursive https://github.com/ocaml-multicore/eio-trace.git
cd eio-trace
dune build
To run an Eio program and display the trace:
dune exec -- eio-trace run -- myprog ...
You might like to start by tracing the example that comes with eio-trace:
dune exec -- eio-trace run -- ./_build/default/examples/net/main.exe
To record a trace:
dune exec -- eio-trace record -f trace.fxt -- myprog ...
This runs myprog ... with the OCAML_RUNTIME_EVENTS_START environment variable set, which causes it to record events to a ring buffer.
eio-trace saves these events to trace.fxt.
The trace can be viewed using generic tools such as Perfetto, but eio-trace's own visualisation is more useful, as it takes advantage of Eio's structured concurrency:
dune exec -- eio-trace show trace.fxt
To convert a trace to SVG format:
dune exec -- eio-trace render -f trace.fxt trace.svg