util: improve format performance #15422

BridgeAR · 2017-09-15T03:38:54Z

After working on util.inspect I thought it might be worth also checking util.format as that is called by console.log.

 util/format.js type="many-%" n=4000000             19.53 %        *** 5.126437e-12
 util/format.js type="no-replace-2" n=4000000       -1.31 %            4.251080e-01
 util/format.js type="no-replace" n=4000000        105.66 %        *** 4.607428e-46
 util/format.js type="number" n=4000000             17.39 %        *** 3.052166e-20
 util/format.js type="only-objects" n=4000000       17.92 %        *** 6.714987e-15
 util/format.js type="replace-object" n=4000000      8.11 %         ** 1.005488e-03
 util/format.js type="string-2" n=4000000           29.12 %        *** 2.679828e-26
 util/format.js type="string" n=4000000             19.40 %        *** 3.171563e-18
 util/format.js type="unknown" n=4000000           103.28 %        *** 1.826116e-40

Checklist

make -j4 test (UNIX), or vcbuild test (Windows) passes
tests and/or benchmarks are included
documentation is changed or added
commit message follows commit guidelines

Affected core subsystem(s)

util

mscdex · 2017-09-15T04:14:08Z

lib/util.js

  }
  if (lastPos === 0)
    str = f;
  else if (lastPos < f.length)
    str += f.slice(lastPos);
  while (a < arguments.length) {
    const x = arguments[a++];
-    if (x === null || (typeof x !== 'object' && typeof x !== 'symbol')) {
+    if (typeof x !== 'object' && typeof x !== 'symbol' || x === null) {


I think this is harder to reason about, which is why I always add extra parentheses so it's always immediately clear (especially to newcomers).

It is interesting to see many people preferring this style. I personally always feel like my brain has to compute a tiny bit more when there are extra braces^^. I changed it back though.

jasnell

LGTM with the exception of @mscdex's comment

BridgeAR · 2017-09-15T19:37:37Z

I found a even better way to optimize for unknown types (e.g. if someone uses a percent as a percent).
I updated the code accordingly and also the benchmark results. So PTAL.

apapirovski · 2017-09-15T21:03:46Z

lib/util.js

@@ -196,8 +196,9 @@ function format(f) {
  var lastPos = 0;
  for (i = 0; i < f.length - 1; i++) {
    if (f.charCodeAt(i) === 37) { // '%'
+      const nextChar = f.charCodeAt(++i);
      if (a !== arguments.length) {


Would it make sense to store arguments.length in a const given the extensive usage throughout format?

Actually, that might be worse for perf after reviewing how V8 handles it. You can ignore, I believe.

BridgeAR · 2017-09-19T20:31:14Z

CI https://ci.nodejs.org/job/node-test-pull-request/10140/

BridgeAR · 2017-09-19T23:06:21Z

Landed in faaefa8

PR-URL: #15422 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>

PR-URL: nodejs/node#15422 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>

MylesBorins · 2017-10-17T18:15:42Z

should this land in LTS? If so it will need to bake a bit longer.

Please change labels as appropriate

BridgeAR · 2018-03-08T11:57:23Z

@MylesBorins I think we could still backport this to 8.x but I am not sure if it applies without conflicts or not. Would you be so kind and check that?

MylesBorins · 2018-03-20T01:41:44Z

@BridgeAR this already landed on 8.x, has conflicts on 6.x

BridgeAR · 2018-03-20T01:48:54Z

Oh, right, I missed that. As 6.x is soon in maintenance only, I do not really think that this has to be backported. I changed the label accordingly.

MylesBorins · 2018-03-20T14:52:13Z

thanks @BridgeAR

in future please add the dont-land label so that things don't show up in tooling

nodejs-github-bot added the util Issues and PRs related to the built-in util module. label Sep 15, 2017

BridgeAR added the performance Issues and PRs related to the performance of Node.js. label Sep 15, 2017

mscdex reviewed Sep 15, 2017

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jasnell approved these changes Sep 15, 2017

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util: improve format performance

d2125d5

BridgeAR force-pushed the improve-util-format branch from 58e8c26 to d2125d5 Compare September 15, 2017 19:37

[squash] improve code readability

c4cce9a

apapirovski reviewed Sep 15, 2017

View reviewed changes

refack approved these changes Sep 19, 2017

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BridgeAR closed this Sep 19, 2017

BridgeAR added a commit that referenced this pull request Sep 19, 2017

util: improve format performance

faaefa8

PR-URL: #15422 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>

jasnell pushed a commit that referenced this pull request Sep 21, 2017

util: improve format performance

fc1448f

PR-URL: #15422 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>

Qard pushed a commit to Qard/ayo that referenced this pull request Sep 21, 2017

util: improve format performance

be98bf9

PR-URL: nodejs/node#15422 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>

Qard pushed a commit to Qard/ayo that referenced this pull request Sep 21, 2017

util: improve format performance

a413129

PR-URL: nodejs/node#15422 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>

MylesBorins added baking-for-lts PRs that need to wait before landing in a LTS release. lts-watch-v6.x labels Oct 17, 2017

BridgeAR mentioned this pull request Dec 20, 2017

doc: warn about using util.inspect/util.format in prod #17791

Closed

3 tasks

BridgeAR removed the baking-for-lts PRs that need to wait before landing in a LTS release. label Mar 8, 2018

BridgeAR removed the lts-watch-v6.x label Mar 20, 2018

MylesBorins added the dont-land-on-v6.x label Mar 20, 2018

BridgeAR deleted the improve-util-format branch April 1, 2019 23:37

BridgeAR mentioned this pull request Dec 20, 2019

for ... of replacing for(;;) in library networking code? #31024

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util: improve format performance #15422

util: improve format performance #15422

BridgeAR commented Sep 15, 2017 •

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BridgeAR commented Mar 20, 2018

MylesBorins commented Mar 20, 2018

util: improve format performance #15422

util: improve format performance #15422

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BridgeAR commented Sep 15, 2017 • edited Loading

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mscdex Sep 15, 2017

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BridgeAR commented Sep 19, 2017

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BridgeAR commented Sep 15, 2017 •

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