Could not find Paint event in trace after last mark

[lifeart]

This issue is not regular, but appear quite often on same HAR file if we have a lot of samples and it cause the whole compare run to fail.

wondering, is a way to enforce paint event inside tracerbench or ignore this assert?

or rerun exact experiment, because it's quite painful to catch this event on attempt №99 (of 100)

looks like closest logic to it landed in https://github.com/TracerBench/tracerbench/pull/200, especially https://github.com/TracerBench/tracerbench/pull/200/files#diff-0f54ca8abebf7489fe5914256d43426b584a7cbca147eeb2bb25c506c62a4299R41

in theory, we could enforce Paint event, like Modernizr do it: https://github.com/Modernizr/Modernizr/blob/master/test/browser/src/mq.js#L29

function enforcePaintEvent() {

    const docElem = document.documentElement;
    const refNode = docElem.firstElementChild || docElem.firstChild;
    const fakeBody = document.createElement('body');
    const div = document.createElement('div');

    div.id = 'mq-test-1';
    div.style.cssText = 'position:absolute;top:-100em';
    fakeBody.style.background = 'none';
    fakeBody.appendChild(div);
    div.innerHTML = '&shy;<style> #mq-test-1 { width: 42px; }</style>';
    docElem.insertBefore(fakeBody, refNode);

    try {
        return div.offsetWidth === 42;
    } finally {
        fakeBody.removeChild(div);
        docElem.removeChild(fakeBody);
    }

}


requestAnimationFrame(() => {
    enforcePaintEvent();
    requestIdleCallback(() => {          __tracerbench.stop();        });
});

[krisselden]

@lifeart can we observe observe({type: 'largest-contentful-paint', buffered: true}) when using the navigation timing marks? also, you shouldn't need to use both requestAnimationFrame and requestIdleCallback, requestIdleCallback is supposed to come in the idle space after paint already.

[krisselden]

We have a todo to add web-vitals metrics, so waiting for them maybe a good idea.

[lifeart]

@krisselden I think so, but this code sometimes throw mentioned error:

without paint event fired