perf(turbo-tasks): Filter out and do not cache unused arguments #75261

bgw · 2025-01-24T06:19:23Z

For trait methods, we often have underscore-prefixed arguments that are unused in method implementations, but must exist on the method signature because the trait requires it.

For example, look at code_generation: https://github.com/search?q=repo%3Avercel%2Fnext.js%20fn%20code_generation&type=code

We can filter those arguments as soon as we resolve the real method, and avoid storing them as part of the task's cache key.

This should mean less data stored per task, and better cache hit rates (so less tasks overall).

This appears to give a roughly 5% memory win:

(Spreadsheet: https://docs.google.com/spreadsheets/d/1fz9Q-tDE6LebS9p4Mci8vZG7jkBSajiMYF1WbZEPnts/edit?usp=sharing)

Full data:

Tested with next-site in front.

Command run:

rm -rf .next && TURBOPACK=1 TURBOPACK_BUILD=1 TURBO_ENGINE_READ_ONLY=1 /bin/time -v pnpm next build --experimental-build-mode=compile

Before, run 1

Compiled in: 19.3s

        Command being timed: "pnpm next build --experimental-build-mode=compile"
        User time (seconds): 121.88
        System time (seconds): 16.74
        Percent of CPU this job got: 501%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:27.61
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 5607868
        Average resident set size (kbytes): 0
        Major (requiring I/O) page faults: 58
        Minor (reclaiming a frame) page faults: 1816374
        Voluntary context switches: 1280636
        Involuntary context switches: 361414
        Swaps: 0
        File system inputs: 102088
        File system outputs: 738000
        Socket messages sent: 0
        Socket messages received: 0
        Signals delivered: 0
        Page size (bytes): 4096
        Exit status: 0

Before, run 2

Compiled in: 19.3s

        Command being timed: "pnpm next build --experimental-build-mode=compile"
        User time (seconds): 124.34
        System time (seconds): 16.97
        Percent of CPU this job got: 516%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:27.36
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 5455968
        Average resident set size (kbytes): 0
        Major (requiring I/O) page faults: 8
        Minor (reclaiming a frame) page faults: 2014509
        Voluntary context switches: 1267794
        Involuntary context switches: 358175
        Swaps: 0
        File system inputs: 6496
        File system outputs: 737296
        Socket messages sent: 0
        Socket messages received: 0
        Signals delivered: 0
        Page size (bytes): 4096
        Exit status: 0

Before, run 3

Compiled in: 18.4s

        Command being timed: "pnpm next build --experimental-build-mode=compile"
        User time (seconds): 117.81
        System time (seconds): 15.86
        Percent of CPU this job got: 505%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:26.46
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 5655912
        Average resident set size (kbytes): 0
        Major (requiring I/O) page faults: 5
        Minor (reclaiming a frame) page faults: 1868540
        Voluntary context switches: 1271444
        Involuntary context switches: 337236
        Swaps: 0
        File system inputs: 7784
        File system outputs: 737480
        Socket messages sent: 0
        Socket messages received: 0
        Signals delivered: 0
        Page size (bytes): 4096
        Exit status:

Before, run 4

Compiled in: 18.2s

        Command being timed: "pnpm next build --experimental-build-mode=compile"
        User time (seconds): 116.98
        System time (seconds): 15.09
        Percent of CPU this job got: 504%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:26.15
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 5962764
        Average resident set size (kbytes): 0
        Major (requiring I/O) page faults: 0
        Minor (reclaiming a frame) page faults: 1861147
        Voluntary context switches: 1253759
        Involuntary context switches: 333116
        Swaps: 0
        File system inputs: 0
        File system outputs: 737304
        Socket messages sent: 0
        Socket messages received: 0
        Signals delivered: 0
        Page size (bytes): 4096
        Exit status: 0

Before, run 5

Compiled in: 17.9s

        Command being timed: "pnpm next build --experimental-build-mode=compile"
        User time (seconds): 119.02
        System time (seconds): 14.84
        Percent of CPU this job got: 516%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:25.92
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 5745780
        Average resident set size (kbytes): 0
        Major (requiring I/O) page faults: 0
        Minor (reclaiming a frame) page faults: 1542655
        Voluntary context switches: 1238600
        Involuntary context switches: 357049
        Swaps: 0
        File system inputs: 0
        File system outputs: 737000
        Socket messages sent: 0
        Socket messages received: 0
        Signals delivered: 0
        Page size (bytes): 4096
        Exit status: 0

After, run 1

Compiled in: 19.0s

        Command being timed: "pnpm next build --experimental-build-mode=compile"
        User time (seconds): 121.85
        System time (seconds): 16.69
        Percent of CPU this job got: 508%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:27.22
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 5402708
        Average resident set size (kbytes): 0
        Major (requiring I/O) page faults: 41
        Minor (reclaiming a frame) page faults: 1822829
        Voluntary context switches: 1221091
        Involuntary context switches: 361604
        Swaps: 0
        File system inputs: 110200
        File system outputs: 737048
        Socket messages sent: 0
        Socket messages received: 0
        Signals delivered: 0
        Page size (bytes): 4096
        Exit status: 0

After, run 2

Compiled in: 18.5s

        Command being timed: "pnpm next build --experimental-build-mode=compile"
        User time (seconds): 119.46
        System time (seconds): 15.32
        Percent of CPU this job got: 506%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:26.60
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 5413980
        Average resident set size (kbytes): 0
        Major (requiring I/O) page faults: 1
        Minor (reclaiming a frame) page faults: 1695775
        Voluntary context switches: 1269774
        Involuntary context switches: 328448
        Swaps: 0
        File system inputs: 800
        File system outputs: 736952
        Socket messages sent: 0
        Socket messages received: 0
        Signals delivered: 0
        Page size (bytes): 4096
        Exit status: 0

After, run 3

Compiled in: 18.5s

        Command being timed: "pnpm next build --experimental-build-mode=compile"
        User time (seconds): 118.15
        System time (seconds): 15.12
        Percent of CPU this job got: 503%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:26.48
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 5312528
        Average resident set size (kbytes): 0
        Major (requiring I/O) page faults: 0
        Minor (reclaiming a frame) page faults: 1893778
        Voluntary context switches: 1277325
        Involuntary context switches: 324591
        Swaps: 0
        File system inputs: 128
        File system outputs: 737304
        Socket messages sent: 0
        Socket messages received: 0
        Signals delivered: 0
        Page size (bytes): 4096
        Exit status: 0

After, run 4

Compiled in: 18.2s

        Command being timed: "pnpm next build --experimental-build-mode=compile"
        User time (seconds): 115.60
        System time (seconds): 15.30
        Percent of CPU this job got: 499%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:26.22
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 5240892
        Average resident set size (kbytes): 0
        Major (requiring I/O) page faults: 1
        Minor (reclaiming a frame) page faults: 1514837
        Voluntary context switches: 1296049
        Involuntary context switches: 312076
        Swaps: 0
        File system inputs: 32
        File system outputs: 737664
        Socket messages sent: 0
        Socket messages received: 0
        Signals delivered: 0
        Page size (bytes): 4096
        Exit status: 0

After, run 5

Compiled in: 19.4s

        Command being timed: "pnpm next build --experimental-build-mode=compile"
        User time (seconds): 125.91
        System time (seconds): 15.63
        Percent of CPU this job got: 514%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:27.50
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 5346672
        Average resident set size (kbytes): 0
        Major (requiring I/O) page faults: 1
        Minor (reclaiming a frame) page faults: 1839175
        Voluntary context switches: 1280293
        Involuntary context switches: 358863
        Swaps: 0
        File system inputs: 32
        File system outputs: 737720
        Socket messages sent: 0
        Socket messages received: 0
        Signals delivered: 0
        Page size (bytes): 4096
        Exit status: 0

Closes PACK-3833

bgw · 2025-01-24T06:19:44Z

perf(turbo-tasks): Filter out and do not cache unused arguments #75261 👈 (View in Graphite)
perf(turbo-tasks): Add a 'local' option to #[turbo_tasks::function(..)] #75259 : 1 other dependent PR (#75260 )
refactor(turbo-tasks): Merge dynamic_call/native_call with dynamic_this_call/native_this_call #75253
chore(turbo-tasks): Remove argument resolution from backends, only allow local-task-based argument resolution #75214
chore(turbo-tasks): Delete non_local_return support from #[turbo_tasks::function] #75209
canary

This stack of pull requests is managed by Graphite. Learn more about stacking.

ijjk · 2025-01-24T06:26:43Z

Tests Passed

ijjk · 2025-01-24T16:51:21Z

Stats from current PR

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Commit: 100c6a7

sokra

Some of the turbo-tasks test cases use _key arguments to make unqiue tasks. Maybe we need to update them to use let _ = arg;

bgw · 2025-01-28T21:21:13Z

Some of the turbo-tasks test cases use _key arguments to make unqiue tasks. Maybe we need to update them to use let _ = arg;

It looks like none of those cases are trait methods, and this PR only impacts trait methods, but I think we should generate a compiler error in the future on non-trait-methods/functions with unused arguments to help ensure some consistency (i.e. that underscored arguments are never used as cache keys).

Using underscored arguments on non-trait-methods/functions is likely a mistake, and there are workarounds (wrapper functions, let _ = arg) if you really need to do that.

I've fixed the cases I could find in the tests.

bgw · 2025-01-28T21:25:09Z

Follow up work: https://linear.app/vercel/issue/PACK-3828/argument-filtering-follow-ups

Add unit tests for the trait method behavior
Error if underscore-prefixed arguments are used on functions or non-trait methods.
Filter unused self arguments on all methods (hard/tricky?).
Add some mention of this behavior to the docs. Ideally after getting the self filtering working as well.

sokra

A test case would be great

bgw · 2025-01-29T21:51:38Z

A test case would be great

I will do this in a follow up. I'm pretty confident nothing's broken by this, but there's some risk we could silently break this optimization without a unit test.

This is a follow-up to: #75261 Tracking issue for these follow-ups: https://linear.app/vercel/issue/PACK-3828/argument-filtering-follow-ups

ijjk added the created-by: Turbopack team PRs by the Turbopack team. label Jan 24, 2025

bgw mentioned this pull request Jan 24, 2025

perf(turbo-tasks): Mark a bunch of stuff as local #75260

Closed

bgw marked this pull request as ready for review January 24, 2025 15:26

bgw marked this pull request as draft January 24, 2025 15:26

bgw force-pushed the bgw/fn-local-option branch from a7429b6 to 40fd0db Compare January 24, 2025 16:30

bgw force-pushed the bgw/filter-unused-args branch from 4dcf00f to f22bdcd Compare January 24, 2025 16:30

bgw force-pushed the bgw/fn-local-option branch from 40fd0db to 2a987b0 Compare January 24, 2025 17:46

bgw force-pushed the bgw/filter-unused-args branch from f22bdcd to 28e47be Compare January 24, 2025 17:46

bgw force-pushed the bgw/fn-local-option branch from 2a987b0 to dd12daa Compare January 24, 2025 18:33

bgw force-pushed the bgw/filter-unused-args branch from 28e47be to 25ef396 Compare January 24, 2025 18:34

bgw force-pushed the bgw/fn-local-option branch 2 times, most recently from 51a826a to 35fc3ed Compare January 24, 2025 19:18

bgw force-pushed the bgw/filter-unused-args branch from 25ef396 to c8519e8 Compare January 24, 2025 19:18

bgw force-pushed the bgw/fn-local-option branch from 35fc3ed to 0151e49 Compare January 24, 2025 19:24

bgw force-pushed the bgw/filter-unused-args branch from c8519e8 to 5c57296 Compare January 24, 2025 19:24

bgw force-pushed the bgw/fn-local-option branch from 0151e49 to 0c17996 Compare January 24, 2025 22:05

bgw changed the base branch from bgw/fn-local-option to graphite-base/75261 January 24, 2025 22:29

bgw force-pushed the bgw/filter-unused-args branch from 5c57296 to 3e43193 Compare January 24, 2025 22:31

bgw force-pushed the graphite-base/75261 branch from 0c17996 to 7578b8f Compare January 24, 2025 22:31

bgw changed the base branch from graphite-base/75261 to canary January 24, 2025 22:31

bgw force-pushed the bgw/filter-unused-args branch 3 times, most recently from 46bad4f to f1e477b Compare January 28, 2025 19:34

bgw requested review from mischnic, sokra and kdy1 January 28, 2025 19:59

bgw marked this pull request as ready for review January 28, 2025 19:59

sokra reviewed Jan 28, 2025

View reviewed changes

bgw added 3 commits January 28, 2025 13:19

perf(turbo-tasks): Filter out and do not cache unused arguments

917171a

Perform filtering in local resolution task

2c3faa5

Don't use underscored arguments in turbo-tasks unit tests

100c6a7

bgw force-pushed the bgw/filter-unused-args branch from f1e477b to 100c6a7 Compare January 28, 2025 21:19

bgw requested a review from sokra January 29, 2025 17:22

sokra approved these changes Jan 29, 2025

View reviewed changes

bgw merged commit 8ed8716 into canary Jan 29, 2025
131 checks passed

bgw deleted the bgw/filter-unused-args branch January 29, 2025 21:51

bgw mentioned this pull request Feb 3, 2025

chore(turbo-tasks): Add test for argument filtering #75585

Merged

bgw added a commit that referenced this pull request Feb 3, 2025

chore(turbo-tasks): Add test for argument filtering (#75585)

73ab21a

This is a follow-up to: #75261 Tracking issue for these follow-ups: https://linear.app/vercel/issue/PACK-3828/argument-filtering-follow-ups

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perf(turbo-tasks): Filter out and do not cache unused arguments #75261

perf(turbo-tasks): Filter out and do not cache unused arguments #75261

bgw commented Jan 24, 2025 •

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perf(turbo-tasks): Filter out and do not cache unused arguments #75261

perf(turbo-tasks): Filter out and do not cache unused arguments #75261

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