devtrace

chrome-tracing

Chrome tracing allows you to automate Chrome benchmarking. It's goal is to provide a JavaScript variant of Telemetry.

Basic Usage

The most basic benchmark is the InitialRenderBenchmark.

import { InitialRenderBenchmark, Runner } from "chrome-tracing";

let control = new InitialRenderBenchmark({
  name: "control",
  url: "http://localhost:8001/",
  endMarker: "renderEnd",
  browser: {
    type: "canary"
  }
});

let experiment = new InitialRenderBenchmark({
  name: "experiment",
  url: "http://localhost:8002/",
  endMarker: "renderEnd",
  browser: {
    type: "canary"
  }
});

let runner = new Runner([control, experiment]);
runner.run(50).then(result => {
  console.log(result);
}).catch(err => {
  console.error(err);
  process.exit(1);
});

In the app you must place a marker to let Chrome Tracing know that you are done rendering. This is done by using a performance.mark function call.

function endTrace() {
  // just before paint
  requestAnimationFrame(function () {
    // after paint
    requestAnimationFrame(function () {
      document.location.href = "about:blank";
    });
  });
}

renderMyApp();
performance.mark("renderEnd");
endTrace();

In the example above we would mark right after we render the app and then call an endTrace function that ensures that we schedule a micro-task after paint that transitions to a blank page. Internally Chrome-Tracing will see this as the cue to start a new sample.

Extending Benchmarks

TODO