events: optimize condition for optimal scenario #20452
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Instead of always checking whether we've already warned about a possible EventEmitter memory leak, first run the rest of the code as accessing random properties on an Array is expensive.
apapirovski
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Can you share benchmark results? |
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@mscdex I'm not claiming it's huge or anything but it's like 1.5-2% with 100 runs. IMO it's a pretty sensible change. The code inside the |
jasnell
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May 1, 2018
lpinca
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bnoordhuis
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May 2, 2018
lib/events.js
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| process.emitWarning(w); | ||
| } | ||
| m = $getMaxListeners(target); | ||
| if (m && m > 0 && existing.length > m && !existing.warned) { |
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If you have time and inclination to test: does reducing m && m > 0 to m > 0 make a difference?
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Not sure if it makes a difference yet but it seems a harmless change and simplifies the conditional further. I don't see why we shouldn't do it.
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CI after the change proposed by @bnoordhuis: https://ci.nodejs.org/job/node-test-pull-request/14621/ |
BridgeAR
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cjihrig
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tniessen
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trivikr
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May 3, 2018
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Landed in fe87945 |
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Instead of always checking whether we've already warned about a possible EventEmitter memory leak, first run the rest of the code as accessing random properties on an Array is expensive. In addition, remove an unnecessary truthy check. PR-URL: #20452 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: Ben Noordhuis <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Tobias Nießen <[email protected]> Reviewed-By: Trivikram Kamat <[email protected]>
MylesBorins
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Instead of always checking whether we've already warned about a possible EventEmitter memory leak, first run the rest of the code as accessing random properties on an Array is expensive. In addition, remove an unnecessary truthy check. PR-URL: #20452 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: Ben Noordhuis <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Tobias Nießen <[email protected]> Reviewed-By: Trivikram Kamat <[email protected]>
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MylesBorins
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Instead of always checking whether we've already warned about a possible EventEmitter memory leak, first run the rest of the code as accessing random properties on an Array is expensive. In addition, remove an unnecessary truthy check. PR-URL: #20452 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: Ben Noordhuis <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Tobias Nießen <[email protected]> Reviewed-By: Trivikram Kamat <[email protected]>
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Instead of always checking whether we've already warned about a possible EventEmitter memory leak, first run the rest of the code as accessing custom properties on an Array is decently slow.
I believe it makes more sense to optimize for well written user-code than code that is already attaching too many listeners and getting this warning, without having set a higher number of maxListeners.
I've also adjusted the benchmark to be a bit more representative as there's too much noise with the current iteration count.
Checklist
make -j4 test(UNIX), orvcbuild test(Windows) passes