new_audit(preload-audit): Adding preload audit #3450

wardpeet · 2017-10-01T13:36:52Z

fixes #931

paulirish · 2017-10-16T20:44:09Z

Let's let this guy chill while we focus on the bootup PRs..

wardpeet · 2017-10-21T13:08:33Z

Some examples:
https://www.paulirish.com/
https://www.theverge.com/
https://www.washingtonpost.com/
https://mobile.nytimes.com/

patrickhulce

nice! I think #3618 could've really helped with this one in particular, seems like a great first start though!

can probably remove gcloud-credentials too :)

patrickhulce · 2017-10-23T18:04:55Z

lighthouse-core/audits/uses-rel-preload.js

+        if (
+          !networkRecord._isLinkPreload && networkRecord.protocol !== 'data'
+        ) {
+          const wastedMs = (request.endTime - request.startTime) * 1000;


Hmmm I'm not sure we can really count this entire request time as wasted, I'm not really sure of a fantastic alternative in absence of a fastmode-based approach. Maybe we can Math.min it with the time spent delayed instead (request.startTime - mainResource.endTime) for now?

Not 100% following the fast-mode part. I kinda missed that whole part..

patrickhulce · 2017-10-23T18:06:05Z

lighthouse-core/config/test-config.js

+'use strict';
+
+module.exports = {
+  extends: 'lighthouse:default',


this was a temporary config right, we can remove this now?

yeah, sorry need to check my PR's a bit better!

patrickhulce · 2017-10-23T18:08:59Z

lighthouse-core/audits/uses-rel-preload.js

+      failureDescription: 'Scripts were discovered late but fetching them earlier may have ' +
+        'improved how quickly the page was interactive',
+      helpText: 'Consider using <link rel=preload> to prioritize fetching late-discovered ' +
+        'resources sooner [Learn more]().',


Maybe we use https://developers.google.com/web/updates/2016/03/link-rel-preload?

not sure, it 100% explains to beginners what it does but I have no better resource

patrickhulce · 2017-10-23T18:10:17Z

lighthouse-core/audits/uses-rel-preload.js

+      category: 'Performance',
+      name: 'uses-rel-preload',
+      description: 'Preload key requests',
+      failureDescription: 'Scripts were discovered late but fetching them earlier may have ' +


we shouldn't need a failureDescription here, scoringMode: numeric I think is what we're looking for

scoringMode? haven't heard about that, what does it do?

oh it basically means that there's no pass/fail state it's just a numeric score :)

wardpeet · 2017-10-25T20:29:20Z

nice! I think #3618 could've really helped with this one in particular, seems like a great first start though!

I can still move the page dep graph if you like :)

patrickhulce · 2018-01-16T18:03:47Z

@wardpeet I wouldn't expect that smoketest to fail this test since we're trying to target resources that were requested very late but still blocking

the only real common case I can think of that will fail this in Chrome is a font requested by a render-blocking stylesheet and document.write

the main case I would want to catch would be font related

root document

<link rel="stylesheet" href="style.css">

style.css

@font-face {
 font-family: "Open Sans";
 src: url("/fonts/OpenSans-Regular-webfont.woff2") format("woff2"),
        url("/fonts/OpenSans-Regular-webfont.woff") format("woff");
}

body {
  font-family: "Open Sans";
}

the main case I would want to catch for document.write would be something like level-2.js and level-3.js in the example below, but we already have a document.write audit telling you not to use it at all so not as concerned about working around document.write with preload :)

root document

<script src="level-1.js"></script>

level-1.js

document.write('<script src="level-2.js"></script>')

level-2.js

document.write('<script src="level-3.js"></script>')

level-3.js

document.body.appendChild(createDiv('Hello!'))

wardpeet · 2018-01-16T21:52:16Z

@patrickhulce thanks! implemented smoketests as you stated. What I see now is that fonts from stylesheets are loaded from the document so they are not part of the depdency tree of critical requests
https://googlechrome.github.io/lighthouse/viewer/?gist=886a702680576c0c9b648f0cc87cecf3

Looking at the page dependencygraph gatherer I have the same issue. It seems like chrome tells us that a font is loaded by the document and not by an external stylesheet so we do not consider it as preloadable.

wardpeet · 2018-02-04T12:22:39Z

@patrickhulce @patrickhulce wasn't 100% sure what was needed here. If not mistaking we were going to do a followup PR to expand this audit to other things than critical request chains.

patrickhulce

yeah we'll punt the criticalness and same-origin changes for a future PR :)

few other odds and ends

patrickhulce · 2018-02-05T17:53:45Z

lighthouse-core/gather/computed/critical-request-chains.js

-      };
+      // add url to be backwards compatible with old CRC
+      // TODO remove in version 3.0
+      request.url = request._url;


what's the purpose of this function now then? .url is already a getter on the request object

I'm slightly nervous about doing this since I'm assuming we needed it for a reason at some point :)

fixed removed indeed

patrickhulce · 2018-02-05T17:54:33Z

lighthouse-core/audits/critical-request-chains.js

+      }
+
+      const request = opts.node.request;
+      chain.request = {


maybe that flatten function is needed over here now?

patrickhulce · 2018-02-05T17:55:07Z

lighthouse-cli/test/smokehouse/smokehouse.js

@@ -265,8 +265,10 @@ const cli = yargs
    'config-path': 'The path to the config JSON file',
    'expectations-path': 'The path to the expected audit results file',
  })
+  .array('save-assets-path')


same story about nixing this here I believe :)

patrickhulce · 2018-02-05T17:55:53Z

lighthouse-cli/test/smokehouse/perf/expectations.js

-    initialUrl: 'http://localhost:10200/online-only.html',
-    url: 'http://localhost:10200/online-only.html',
+    initialUrl: 'http://localhost:10200/preload.html',
+    url: 'http://localhost:10200/preload.html',


if we're changing this URL do we need the separate entry below still?

patrickhulce · 2018-02-05T18:04:27Z

lighthouse-core/audits/uses-rel-preload.js

+        const networkRecord = request;
+        if (!networkRecord._isLinkPreload && networkRecord.protocol !== 'data') {
+          // calculate time between mainresource.endTime and resource start time
+          const wastedMs = (request._startTime - mainResource._endTime) * 1000;


let's also Math.min this with the total length of the request

CNN tells me you could save 20s by preloading a tracking pixel that only took ~700ms to load :)

now Math.min is shown :)

oh @wardpeet I meant doing

const wastedMs = Math.min(request._startTime - mainResource._endTime, request._endTime - request._startTime) * 1000

seems like I misread that...

patrickhulce · 2018-02-05T18:06:11Z

lighthouse-core/audits/uses-rel-preload.js

+    return {
+      category: 'Performance',
+      name: 'uses-rel-preload',
+      description: 'Preload key requests',


let's mark this as informative: true

patrickhulce · 2018-02-07T21:13:48Z

lighthouse-core/config/test.js

+ */
+'use strict';
+
+module.exports = {


seems like we might not need this anymore?

paulirish

let's do it.

what's up october 2017. welcome to the ❕ⓝⓞⓦ❕

wardpeet added this to the Loading Performance Audits milestone Oct 1, 2017

paulirish modified the milestones: Loading Performance Audits, Sprint Uno: Oct 2-13 Oct 2, 2017

patrickhulce mentioned this pull request Oct 13, 2017

Text compression with HTTP2 tip #3548

Closed

paulirish modified the milestones: Sprint Uno: Oct 2-13, Sprint Dos: Oct 16-27 Oct 16, 2017

paulirish removed this from the Sprint Dos: Oct 16-27 milestone Oct 16, 2017

paulirish added the chillin ❄ label Oct 16, 2017

wardpeet force-pushed the feature/preload branch from b02437a to 018df55 Compare October 21, 2017 15:38

wardpeet requested review from brendankenny, patrickhulce and paulirish as code owners October 21, 2017 15:38

wardpeet force-pushed the feature/preload branch from 018df55 to 2cb9f33 Compare October 21, 2017 15:40

patrickhulce suggested changes Oct 23, 2017

View reviewed changes

addyosmani added this to the Sprint Tres: Oct 30 - Nov 12 milestone Oct 30, 2017

wardpeet added the waiting4reviewer label Oct 30, 2017

wardpeet changed the title ~~feature(preload-audit): Adding preload audit~~ new_audit(preload-audit): Adding preload audit Nov 3, 2017

vinamratasingal-zz modified the milestones: Sprint Tres: Oct 30 - Nov 12, Sprint Quatro: November 13-26 Nov 13, 2017

paulirish modified the milestones: Sprint Quatro: November 13-26, Sprint Cinco: November 28 - Dec 9 Nov 27, 2017

paulirish self-assigned this Nov 28, 2017

paulirish mentioned this pull request Nov 28, 2017

Refactor CRChains to use the lantern dependency graph #3938

Open

wardpeet force-pushed the feature/preload branch from 32c5a74 to 8194adc Compare January 13, 2018 14:41

Fix preload, tests and smoketest

31c838d

Fixed smoketests

ae68a0e

wardpeet force-pushed the feature/preload branch from ae978de to ae68a0e Compare January 17, 2018 21:07

paulirish modified the milestones: Sprint Siete: January 8-19, Sprint Ocho: January 29 - Feb 9 Jan 29, 2018

paulirish assigned patrickhulce Jan 31, 2018

patrickhulce suggested changes Feb 5, 2018

View reviewed changes

patrickhulce added waiting4committer and removed waiting4reviewer labels Feb 5, 2018

wardpeet added 2 commits February 5, 2018 22:33

Remove save-assets-path

1164106

Review changes

930cad4

devtools-bot added waiting4reviewer and removed waiting4committer labels Feb 5, 2018

wardpeet added 3 commits February 5, 2018 23:37

Fix unit tests

c468866

Fix review wasted time

c2534f6

Fix smoketest

6acd392

paulirish mentioned this pull request Feb 5, 2018

Preload audit improvements #4425

Closed

2 tasks

wardpeet and others added 3 commits February 6, 2018 08:08

Fix travis

14c36f9

remove unnecessary parens

b9591f0

Merge branch 'master' into feature/preload

d18b045

patrickhulce reviewed Feb 7, 2018

View reviewed changes

lighthouse-core/config/test.js Outdated

*/

'use strict';

module.exports = {

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patrickhulce Feb 7, 2018

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seems like we might not need this anymore?

remove test config

6e4b183

paulirish approved these changes Feb 8, 2018

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paulirish merged commit e9ff105 into master Feb 8, 2018

paulirish deleted the feature/preload branch February 8, 2018 00:18

paulirish removed the waiting4reviewer label Mar 6, 2018

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new_audit(preload-audit): Adding preload audit #3450

new_audit(preload-audit): Adding preload audit #3450

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new_audit(preload-audit): Adding preload audit #3450

new_audit(preload-audit): Adding preload audit #3450

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wardpeet commented Oct 25, 2017

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root document

style.css

root document

level-1.js

level-2.js

level-3.js

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