core(computed-artifacts): fix cache and add perf timing #6619
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brendankenny
commented
Nov 20, 2018
| const artifactPromise = /** @type {ReturnType<C['compute_']>} */ | ||
| (computableArtifact.compute_(artifacts, context)); | ||
| cache.set(artifacts, artifactPromise); | ||
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| artifactPromise.then(() => log.timeEnd(status)).catch(() => log.timeEnd(status)); |
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this is unfortunate until we have Promise.finally :) (standard in Node 10)
Otherwise if there's a error thrown in the computed artifact this branch is considered an unhandled rejection and we try to kill Lighthouse early.
paulirish
approved these changes
Nov 20, 2018
| @@ -12,7 +12,7 @@ const assert = require('assert'); | |||
| const makeComputedArtifact = require('../../computed/computed-artifact.js'); | |||
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| describe('ComputedArtifact base class', () => { | |||
| it.skip('caches computed artifacts by strict equality', async () => { | |||
| it('caches computed artifacts by strict equality', async () => { | |||
| let computeCounter = 0; | |||
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| const TestComputedArtifact = makeComputedArtifact(class TestComputedArtifact { | |||
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class as expression hurts my head, especially since it has the same name as something different
can you extract?
effect isn't huge huge, but it helps. An |
| @@ -12,19 +12,19 @@ const assert = require('assert'); | |||
| const makeComputedArtifact = require('../../computed/computed-artifact.js'); | |||
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| describe('ComputedArtifact base class', () => { | |||
| it.skip('caches computed artifacts by strict equality', async () => { | |||
| @@ -3474,6 +3474,12 @@ | |||
| "duration": 100, | |||
| "entryType": "measure" | |||
| }, | |||
| { | |||
| "startTime": 0, | |||
| "name": "lh:computed:NetworkRecords", | |||
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split off from #6618
log timing was added at the same time that core: convert computed artifact loading to regular require() #6204 updated computed artifacts, so timing info hasn't actually been collected for computed artifacts (timing was still accounted for in the audits that called them, though). This PR adds timing to the new version.
core: convert computed artifact loading to regular require() #6204 messed up and was using strict equality testing for the computed artifact cache, not deep equality. Computed artifacts that take a bare artifact (e.g.
trace-of-tab) had no issue with this and cached correctly. Any computed artifact that take a more complicated input (e.g. all the metrics) always found keys to be unequal, and so reran their computations every time they were called. This was especially bad in the lantern metrics, which tend to call each other a lot and benefit a good deal from caching.This PR defaults
ArbitraryEqualityMapto using deep equality now (since that's the only way we use it), and the kind of goofball test updated incomputed-artifact-test.jsproved it's worth and will prevent this from regressing again.Good news: runs should speed up :)