browser_memory_distribution_telemetry.js

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"use strict";

const { TelemetrySession } = ChromeUtils.importESModule(

  "resource://gre/modules/TelemetrySession.sys.mjs"

);

const DUMMY_PAGE_DATA_URI = `data:text/html,

    <html>

      <head>

        <meta charset="utf-8"/>

        <title>Dummy</title>

      </head>

      <body>

        <h1 id='header'>Just a regular everyday normal page.</h1>

      </body>

    </html>`;

/**

 * Tests the MEMORY_DISTRIBUTION_AMONG_CONTENT probe by opening a few tabs, then triggering

 * the memory probes and waiting for the "gather-memory-telemetry-finished" notification.

*/

add_task(async function test_memory_distribution() {

  waitForExplicitFinish();

  if (SpecialPowers.getIntPref("dom.ipc.processCount", 1) < 2) {

    ok(true, "Skip this test if e10s-multi is disabled.");

    finish();

    return;

  Services.telemetry.canRecordExtended = true;

  let histogram = Services.telemetry.getKeyedHistogramById(

    "MEMORY_DISTRIBUTION_AMONG_CONTENT"

);

  histogram.clear();

  let tab1 = await BrowserTestUtils.openNewForegroundTab(

    gBrowser,

    DUMMY_PAGE_DATA_URI

);

  let tab2 = await BrowserTestUtils.openNewForegroundTab(

    gBrowser,

    DUMMY_PAGE_DATA_URI

);

  let tab3 = await BrowserTestUtils.openNewForegroundTab(

    gBrowser,

    DUMMY_PAGE_DATA_URI

);

  let finishedGathering = new Promise(resolve => {

    let obs = function () {

      Services.obs.removeObserver(obs, "gather-memory-telemetry-finished");

      resolve();

};

    Services.obs.addObserver(obs, "gather-memory-telemetry-finished");

});

  TelemetrySession.getPayload();

  await finishedGathering;

  let s = histogram.snapshot();

  ok("0 - 10 tabs" in s, "We should have some samples by now in this bucket.");

  for (var key in s) {

    is(key, "0 - 10 tabs");

    let fewTabsSnapshot = s[key];

    Assert.greater(

      fewTabsSnapshot.sum,

0,

      "Zero difference between all the content processes is unlikely, what happened?"

);

    Assert.less(

      fewTabsSnapshot.sum,

80,

      "20 percentage difference on average is unlikely, what happened?"

);

    let values = fewTabsSnapshot.values;

    for (let [bucket, value] of Object.entries(values)) {

      if (bucket >= 10) {

        // If this check fails it means that one of the content processes uses at least 20% more or 20% less than the mean.

        is(value, 0, "All the buckets above 10 should be empty");

  histogram.clear();

  BrowserTestUtils.removeTab(tab3);

  BrowserTestUtils.removeTab(tab2);

  BrowserTestUtils.removeTab(tab1);

  finish();

});