Profiling

A profiler is shipped by lde, using LuaJIT’s highly performant sampling profiler that can be used in production environments due to its minimal overhead.

lde run --profile

The report shows two things:

• A VM state breakdown: JIT compiled, interpreted, C code, GC, and JIT compiler time.
  • This is useful to try and minimize the amount of time spent in interpreted code and in GC.
• A hotspot table with the top 20 functions by sample count.
  • Helpful to figure out which functions are taking up the most time.

Flamegraphs

lde run --flamegraph writes an interactive flamegraph:

lde run --flamegraph

This generates a self contained profile.html file. You can open it in any browser, hover over frames, click to expand.

JSON output

lde run --profile --json writes the raw sampled data as JSON. This is useful for historical metrics, or feeding into tooling like llms for analysis.

lde run --profile --json profile.json