perf(genAdds): refactor recursive procedure to iterative #1277

JonasBa · 2023-08-07T19:52:34Z

Not sure how representative the benchmark is, so I'm adding the screenshot of the profile (deep DOM tree benchmark). Looking at timings, it seems to take ~18ms before and 13ms after my change, or about ~30% gain. Feel free to do more extensive benchmarking and take those timings with a grain of salt as I just ran the benchmarks once

Before

After

We can see the stack is shallower as expected (and uses less memory, sadly no metrics on that).
A small benefit is that we also remove the overhead of calling into the polymorphic genAdds fn.

The queue has a magic default size of 1000 - feel free to tweak that to some better value, I'm not sure what a sensible default could be here

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JonasBa · 2023-08-15T13:37:38Z

@eoghanmurray nice find on the blocked, I moved that too quickly. Feel free to just leave a review next time and I'm happy to work on the changes

eoghanmurray · 2023-08-17T13:06:52Z

I'm tempted to leave the Array pre-allocation out of this PR for code readability reasons.
If it's important likely we should be doing it in other places; unless there's a particular reason for it here?

Also, this article suggests the V8 engine is much more performant with .push anyway:
https://dev.to/henryjw/populating-a-pre-allocated-array-slower-than-a-pushing-to-a-regular-array-4l43

eoghanmurray · 2023-08-17T13:08:33Z

We should also include the test changes in this PR also for further review — see the yarn test:update command (I can run this for you if you prefer, but you mentioned you had checked the output?)

JonasBa · 2023-08-17T13:18:36Z

@eoghanmurray no problem, let me make the change.

Is there a reason that you decided to move genAdds inside the childlist case here btw?

JonasBa · 2023-08-17T13:24:50Z

@eoghanmurray I updated the PR based on your review

eoghanmurray · 2023-08-24T11:15:49Z

Is there a reason that you decided to move genAdds inside the childlist case here btw?

Do you mean f5f9789 ?
I imagine genAdds was originally separate only because it was recursive.

JonasBa · 2023-08-25T19:06:12Z

Yeah, thats what I meant. Lmk if I need to update anything else

eoghanmurray · 2023-08-30T14:00:24Z

I'm not sure why the test is failing

JonasBa · 2023-08-30T15:07:49Z

Seems unrelated, I will rebase the PR

JonasBa · 2023-08-31T00:53:09Z

I think my dev env must have picked up a different TS version.
What I see in serialize-args is this error

which gets corrected to another error...

I reverted the changes, it should now be ok.

JonasBa · 2023-08-31T00:57:52Z

packages/rrweb/src/record/mutation.ts

+            const next = genAddsQueue.pop();
+            if (!next) {
+              throw new Error(
+                'Add queue is corrupt, there is no next item to process',


this should be unreachable. I can add a continue clause in case we don't want to throw, or just silence ts if that's the preference

JonasBa · 2023-09-25T03:33:28Z

@eoghanmurray friendly ping :)

JonasBa · 2023-10-05T17:27:03Z

@eoghanmurray small ping here :)

eoghanmurray · 2023-10-09T13:58:15Z

Apologies for delay; do you have this running in production?

I've just cherry-picked this PR today and am putting it out in a 'canary' environment to a subset of customers.

Reasons to be cautious: I've fixed a completely separate 'node ordering' issue on the replay side of things, where non-anticipated ordering of nodes in a mutation produced worst case performance and ultimately broke the replay (as it triggered a timeout).
Fix is here #1320 so hopefully that acts as a vote in favour of this one as we should be more robust at replay time now.

JonasBa · 2023-10-09T14:47:49Z

Apologies for delay; do you have this running in production?

We do not.

I've just cherry-picked this PR today and am putting it out in a 'canary' environment to a subset of customers.

Perfect, let me know.

I looked at your PR about node ordering issue, but since it's been a while since I looked at this code I lost some context and requirements, so I have a hard time imagining the exact issue you are fixing.

JonasBa · 2023-11-20T13:12:30Z

@eoghanmurray any findings from the canary builds here?

eoghanmurray · 2023-11-23T15:42:18Z

No issues that I know of

bruno-garcia · 2023-12-01T19:00:15Z

I've just cherry-picked this PR today and am putting it out in a 'canary' environment to a subset of customers.

Does it give the confidence we need to merge this one in? Wondering if we should be cherry-picking it too or it merges here and update our fork

eoghanmurray · 2024-04-14T07:03:13Z

See also #1398 ... I'm trying to work out how these two PRs might interact

JonasBa · 2024-04-14T14:38:47Z

@eoghanmurray I think my PR already implements the changes from that PR as it performs an in-order traversal to enqueue items and then proceeds to pop the items from the queue (lifo), which is the essentially the same as iterating backwards as you process items with the added benefit that we remove recursion

eoghanmurray · 2024-04-15T09:27:26Z

Super, I missed that it was LIFO.
No need for unshift so

JonasBa · 2024-04-15T13:19:52Z

Yeah, you want to avoid unshift in this case because it's On. We would have had to use a list in this case. Btw, whats the status of this PR, can we merge this or do you want me to do anything else here?

eoghanmurray · 2024-04-15T22:15:53Z

I think we should have merged a long time ago, however with something like this it's hard to tell if there isn't some case where it makes things worse (not that I believe this is the case from having examined it).

I meant to put together another 'throw everything at it' mutation benchmark test today with this in mind, but ran into some technical issues.

I think it will be merged soon.

eoghanmurray · 2024-04-15T22:17:07Z

You could rebase/merge on master which will re-trigger fresh tests; not sure if the indicated test failure is significant (it is no longer available for viewing).

eoghanmurray · 2024-04-17T14:16:03Z

To summarize benchmarks: they don't show any difference (so probably aren't exacting enough?)

JonasBa · 2024-04-17T14:24:39Z

@eoghanmurray I need to look more into it. There is a chance that benchmarks are not impacted because the depth of the benchmarked DOM is in most cases fairly shallow, which could mean recursive calls are never deep enough to impact these benchmarks.

I may create a separate benchmark to test adding deep DOM trees, it should be something we should benchmark for.

JonasBa · 2024-04-24T12:14:59Z

@eoghanmurray I wont have the time to look into adding a proper benchmark here soon. Can this still be merged or should we wait for that?

JonasBa · 2024-04-29T15:29:14Z

@eoghanmurray Any chance we could merge this? I would like to move over to splitting down the other larger PR I had

JonasBa · 2024-05-16T16:47:05Z

@eoghanmurray ping

JonasBa · 2024-05-28T13:19:49Z

@eoghanmurray I realized that the benchmarks were so similar because I wasnt rebuilding the packages and running yarn benchmark from within the rrweb package.

I've reran the benchmarks with the following results. The largest change was observed on the append 1000 elements and reverse their order benchmark where perf seems to have improved by 15%. The other benchmarks seem to have all stayed within a few % of the current value. The metrics of each these runs look like standard error, so I dont think we can take them into account

1121ms -> 1075ms
'append 70 x 70 x 70 elements' │ 3 │ 1121.3333333333333 │ '1128, 1117, 1119'
'append 70 x 70 x 70 elements' │ 3 │ 1075.6666666666667 │ '1071, 1094, 1062'

165ms -> 140ms -15% (largest change)
'append 1000 elements and reverse their order' │ 3 │ 165.33333333333334 │ '165, 168, 163'
'append 1000 elements and reverse their order' │ 3 │ 140.33333333333334 │ '139, 141, 141'

1390ms -> 1401ms
'real events recorded on bugs.chromium.org' │ 3 │ 1390 │ '1430, 1348, 1392'
'real events recorded on bugs.chromium.org' │ 3 │ 1401.3333333333333 │ '1465, 1388, 1351'

81.7m -> 82.9ms
'create 1000x10x2 DOM nodes and remove a bunch of them' │ 'benchmark-dom-mutation-add-and-remove.html' │ 'window.workload()' │ 10 │ 81.7 │ '84, 77, 81, 92, 76, 77, 95, 80, 79, 76'
'create 1000x10x2 DOM nodes and remove a bunch of them' │ 'benchmark-dom-mutation-add-and-remove.html' │ 'window.workload()' │ 10 │ 82.9 │ '82, 80, 79, 91, 79, 85, 96, 79, 75, 83'

54ms -> 56ms
'create 1000x10 DOM nodes' │ 'benchmark-dom-mutation.html' │ 'window.workload()' │ 10 │ 54 │ '53, 53, 54, 52, 53, 57, 53, 52, 56, 57'
'create 1000x10 DOM nodes' │ 'benchmark-dom-mutation.html' │ 'window.workload()' │ 10 │ 56.1 │ '52, 55, 55, 53, 55, 56, 54, 51, 71, 59'

22.8 -> 21.8
'create 1000 DOM nodes and append into its previous looped node' │ 'benchmark-dom-mutation-multiple-descendant-add.html' │ 'window.workload()' │ 5 │ 22.8 │ '23, 23, 22, 23, 23'
'create 1000 DOM nodes and append into its previous looped node' │ 'benchmark-dom-mutation-multiple-descendant-add.html' │ 'window.workload()' │ 5 │ 21.8 │ '21, 22, 22, 22, 22'

89.6ms -> 89.8ms
'create 10000 DOM nodes and move it to new container' │ 'benchmark-dom-mutation-add-and-move.html' │ 'window.workload()' │ 5 │ 89.6 │ '90, 95, 86, 91, 86'
'create 10000 DOM nodes and move it to new container' │ 'benchmark-dom-mutation-add-and-move.html' │ 'window.workload()' │ 5 │ 89.8 │ '87, 100, 89, 87, 86'

19.3ms -> 17.9ms
'modify attributes on 10000 DOM nodes' │ 'benchmark-dom-mutation-attributes.html' │ 'window.workload()' │ 10 │ 19.3 │ '18, 24, 17, 18, 28, 17, 18, 16, 17, 20'
'modify attributes on 10000 DOM nodes' │ 'benchmark-dom-mutation-attributes.html' │ 'window.workload()' │ 10 │ 17.9 │ '17, 16, 18, 20, 15, 19, 19, 16, 23, 16'

…ersion

…o#1489)

eoghanmurray · 2024-07-12T17:56:32Z

I've rebased on master and cleaned up a little in https://github.com/eoghanmurray/rrweb/tree/genadds-recursion
One of the tests has already been introduced in #1489 so I wasn't sure what the intention was there; I've added a new benchmark-dom-mutation command in package.json (although I haven't tested whether it does what it's supposed to, i.e. just call that one new benchmark test)

If that branch is acceptable you can git reset --hard 2b8de82f9bbe04819b230189ac70bb2a71270823 and git push --force to this branch; I don't have write access to this PR even though Maintainers are allowed to edit this pull request.
I get the following error in console:

$ git push -f JonasBa
...
To github.com:JonasBa/rrweb.git
 ! [remote rejected]     genadds-recursion -> genadds-recursion (permission denied)
error: failed to push some refs to 'github.com:JonasBa/rrweb.git'

eoghanmurray · 2024-07-12T17:57:06Z

(I thought this branch was already merged)

JonasBa · 2024-07-18T15:20:15Z

@eoghanmurray the tests fail because the order of iteration is reversed, which is expected given the changes (iirc this doesnt have an effect), but please lmk if it does and I can see if there is something I can fix

eoghanmurray · 2024-07-24T15:15:53Z

So do I understand it correctly again that this changes things from depth first to breadth first?
If that's the case, is there any sense in reversing the order of breadth so that at least the first 'level' will match? This would be just to minimize the test changes and make them easier to review; this is likely a crazy notion.

Otherwise we'll need to test:update the snapshots and really review those changes very carefully to make sure nothing unexpected slips in.

JonasBa · 2024-09-19T15:47:14Z

@eoghanmurray I'm going to close this PR as it has been broken down into individual prs

eoghanmurray · 2025-02-04T19:03:08Z

Is #1539 the equivalent? Are you sure this isn't still important?

JonasBa mentioned this pull request Aug 7, 2023

fix(perf): improve perf of mutation and snapshot #1271

Closed

eoghanmurray force-pushed the jb/perf/genadds-recursion branch 2 times, most recently from a0284c0 to f5f9789 Compare August 15, 2023 09:52

JonasBa commented Aug 31, 2023

View reviewed changes

eoghanmurray force-pushed the jb/perf/genadds-recursion branch from 3ef5f64 to cd2ea39 Compare December 4, 2023 14:51

JonasBa force-pushed the jb/perf/genadds-recursion branch from cd2ea39 to ebe0db6 Compare April 17, 2024 11:27

colingm mentioned this pull request May 1, 2024

perf(genadds) traverse children in reverse order #1398

Closed

JonasBa mentioned this pull request May 30, 2024

perf(mutation): refactor parent removed detection to iterative procedure #1489

Merged

JonasBa and others added 7 commits July 12, 2024 18:50

ref(genAdds): refactor to iterative

0d630e4

return should have been converted to continue for the iterative v…

82dab76

…ersion

No need for a separately named genAdds function if it's not recursive

337b05d

ref(mutation): use arr push

deeb233

ref(mutation): update snapshot

d23ce75

perf(mutation): dont reschedule nodes if they exist in the set

30548a2

eoghan: add way to call deep recursive test (already added in rrweb-i…

2b8de82

…o#1489)

JonasBa force-pushed the jb/perf/genadds-recursion branch from 0435984 to 2b8de82 Compare July 17, 2024 21:28

fix test cmd

20f1ca7

JonasBa added 5 commits July 18, 2024 14:17

fix benchmark boilerplate code

bfe56c4

run prettier

6059038

reverse iterate to fix test

77d8762

run prettier

5e3808a

use for loop

4a984b0

JonasBa closed this Sep 19, 2024

eoghanmurray mentioned this pull request Feb 4, 2025

perf(rrweb): optimize random shuffled addList #1302

Draft

perf(genAdds): refactor recursive procedure to iterative #1277

perf(genAdds): refactor recursive procedure to iterative #1277

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