lib: narrow `Atomics.wait*` target to SharedArrayBuffer views by Renegade334 · Pull Request #61817 · microsoft/TypeScript

Renegade334 · 2025-06-04T21:54:46Z

The Atomics.wait* methods only accept views over SharedArrayBuffers, and will throw a TypeError if passed a view on an ArrayBuffer. Since #59417, it's now possible to express this in the method declarations.

This change seems like it should have a favourable utility-to-annoyance ratio, but it would be interesting to see what the user tests say.

(The same does not apply to Atomics.notify(), since although it's a no-op if passed a non-shared view, it accepts the argument and completes gracefully.)

typescript-bot · 2025-06-04T21:54:50Z

This PR doesn't have any linked issues. Please open an issue that references this PR. From there we can discuss and prioritise.

jakebailey · 2025-06-04T23:17:13Z

@typescript-bot test it

typescript-bot · 2025-06-04T23:17:17Z

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
`test top400`	✅ Started	✅ Results
`user test this`	✅ Started	✅ Results
`run dt`	✅ Started	✅ Results
`perf test this faster`	✅ Started	👀 Results

typescript-bot · 2025-06-04T23:39:13Z

Hey @jakebailey, the results of running the DT tests are ready.

Everything looks the same!

You can check the log here.

typescript-bot · 2025-06-04T23:42:12Z

@jakebailey Here are the results of running the user tests with tsc comparing main and refs/pull/61817/merge:

Everything looks good!

typescript-bot · 2025-06-05T00:07:23Z

@jakebailey
The results of the perf run you requested are in!

Here they are:

tsc

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-Unions - node (v18.15.0, x64)}
_Errors	₃₄	₃₄	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_62,390	_62,390	_~	_~	_~	_{p=1.000 n=6}
_Types	_50,395	_50,395	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{194,121k (± 0.94%)}	_{192,930k (± 0.01%)}	_{-1,191k (- 0.61%)}	_192,903k	_192,943k	_{p=0.020 n=6}
_{Parse Time}	_{1.31s (± 0.79%)}	_{1.32s (± 0.42%)}	_~	_1.31s	_1.32s	_{p=0.138 n=6}
_{Bind Time}	_0.73s	_0.73s	_~	_~	_~	_{p=1.000 n=6}
_{Check Time}	_{9.74s (± 0.15%)}	_{9.72s (± 0.24%)}	_~	_9.69s	_9.74s	_{p=0.192 n=6}
_{Emit Time}	_{2.72s (± 0.50%)}	_{2.74s (± 0.88%)}	_~	_2.71s	_2.77s	_{p=0.363 n=6}
_{Total Time}	_{14.50s (± 0.20%)}	_{14.50s (± 0.16%)}	_~	_14.46s	_14.53s	_{p=0.683 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₅₆	₅₆	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_949,240	_949,240	_~	_~	_~	_{p=1.000 n=6}
_Types	_411,065	_411,065	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{1,225,111k (± 0.00%)}	_{1,225,067k (± 0.00%)}	_~	_1,225,027k	_1,225,111k	_{p=0.173 n=6}
_{Parse Time}	_{6.60s (± 0.86%)}	_{6.63s (± 0.79%)}	_~	_6.57s	_6.68s	_{p=0.224 n=6}
_{Bind Time}	_{1.88s (± 0.55%)}	_{1.89s (± 0.40%)}	_~	_1.88s	_1.90s	_{p=0.351 n=6}
_{Check Time}	_{31.83s (± 0.12%)}	_{31.76s (± 0.55%)}	_~	_31.50s	_31.96s	_{p=0.375 n=6}
_{Emit Time}	_{14.87s (± 0.20%)}	_{14.86s (± 0.72%)}	_~	_14.77s	_15.00s	_{p=0.374 n=6}
_{Total Time}	_{55.18s (± 0.11%)}	_{55.14s (± 0.45%)}	_~	_54.77s	_55.52s	_{p=0.748 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,577,125	_2,577,125	_~	_~	_~	_{p=1.000 n=6}
_Types	_892,437	_892,437	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,856,018k (± 0.00%)}	_{2,856,052k (± 0.00%)}	_~	_2,855,997k	_2,856,183k	_{p=0.810 n=6}
_{Parse Time}	_{9.08s (± 0.22%)}	_{9.09s (± 0.41%)}	_~	_9.03s	_9.12s	_{p=0.519 n=6}
_{Bind Time}	_{2.29s (± 0.53%)}	_{2.29s (± 0.18%)}	_~	_2.28s	_2.29s	_{p=0.863 n=6}
_{Check Time}	_{87.67s (± 0.41%)}	_{87.65s (± 0.27%)}	_~	_87.27s	_87.94s	_{p=0.748 n=6}
_{Emit Time}	_0.30s	_0.30s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{99.33s (± 0.36%)}	_{99.32s (± 0.28%)}	_~	_98.88s	_99.63s	_{p=0.810 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,228,521	_1,228,521	_~	_~	_~	_{p=1.000 n=6}
_Types	_267,368	_267,368	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,665,319k (±13.48%)}	_{2,360,198k (± 0.03%)}	_{🟩-305,121k (-11.45%)}	_2,359,609k	_2,360,834k	_{p=0.045 n=6}
_{Parse Time}	_{5.27s (± 1.76%)}	_{5.20s (± 0.67%)}	_~	_5.13s	_5.22s	_{p=0.297 n=6}
_{Bind Time}	_{1.81s (± 1.43%)}	_{1.81s (± 0.76%)}	_~	_1.78s	_1.82s	_{p=0.934 n=6}
_{Check Time}	_{35.38s (± 0.82%)}	_{35.51s (± 0.49%)}	_~	_35.29s	_35.70s	_{p=0.377 n=6}
_{Emit Time}	_{3.01s (± 1.18%)}	_{2.99s (± 0.34%)}	_~	_2.98s	_3.01s	_{p=0.376 n=6}
_{Total Time}	_{45.46s (± 0.72%)}	_{45.51s (± 0.45%)}	_~	_45.21s	_45.72s	_{p=0.748 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,228,521	_1,228,521	_~	_~	_~	_{p=1.000 n=6}
_Types	_267,368	_267,368	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,794,253k (±14.30%)}	_{2,794,249k (±14.27%)}	_~	_2,428,992k	_3,159,223k	_{p=0.936 n=6}
_{Parse Time}	_{6.82s (± 1.91%)}	_{6.80s (± 1.13%)}	_~	_6.71s	_6.91s	_{p=0.936 n=6}
_{Bind Time}	_{2.19s (± 1.10%)}	_{2.21s (± 1.89%)}	_~	_2.15s	_2.26s	_{p=0.572 n=6}
_{Check Time}	_{42.77s (± 0.55%)}	_{42.80s (± 0.45%)}	_~	_42.51s	_43.02s	_{p=0.873 n=6}
_{Emit Time}	_{3.58s (± 2.97%)}	_{3.57s (± 2.42%)}	_~	_3.46s	_3.69s	_{p=0.873 n=6}
_{Total Time}	_{55.38s (± 0.30%)}	_{55.39s (± 0.40%)}	_~	_55.11s	_55.61s	_{p=0.936 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_263,435	_263,435	_~	_~	_~	_{p=1.000 n=6}
_Types	_107,110	_107,110	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{441,763k (± 0.02%)}	_{441,723k (± 0.01%)}	_~	_441,658k	_441,776k	_{p=0.471 n=6}
_{Parse Time}	_{3.54s (± 0.52%)}	_{3.55s (± 0.93%)}	_~	_3.51s	_3.59s	_{p=1.000 n=6}
_{Bind Time}	_{1.32s (± 0.89%)}	_{1.32s (± 1.39%)}	_~	_1.30s	_1.35s	_{p=0.934 n=6}
_{Check Time}	_{18.95s (± 0.26%)}	_{18.96s (± 0.61%)}	_~	_18.82s	_19.13s	_{p=0.809 n=6}
_{Emit Time}	_{1.54s (± 0.97%)}	_{1.53s (± 1.23%)}	_~	_1.51s	_1.56s	_{p=0.121 n=6}
_{Total Time}	_{25.36s (± 0.22%)}	_{25.36s (± 0.55%)}	_~	_25.15s	_25.52s	_{p=0.872 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₇₁	₇₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_225,981	_225,981	_~	_~	_~	_{p=1.000 n=6}
_Types	_94,356	_94,356	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{371,320k (± 0.05%)}	_{371,309k (± 0.04%)}	_~	_371,204k	_371,616k	_{p=0.936 n=6}
_{Parse Time}	_{2.89s (± 1.45%)}	_{2.89s (± 0.83%)}	_~	_2.87s	_2.92s	_{p=1.000 n=6}
_{Bind Time}	_{1.60s (± 1.02%)}	_{1.58s (± 1.11%)}	_~	_1.57s	_1.61s	_{p=0.256 n=6}
_{Check Time}	_{16.46s (± 0.34%)}	_{16.50s (± 0.20%)}	_~	_16.47s	_16.56s	_{p=0.148 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{20.94s (± 0.26%)}	_{20.98s (± 0.30%)}	_~	_20.91s	_21.08s	_{p=0.470 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₃₈	₃₈	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_3,495,222	_3,495,222	_~	_~	_~	_{p=1.000 n=6}
_Types	_1,180,280	_1,180,282	_{+2 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{3,536,957k (± 0.00%)}	_{3,536,933k (± 0.01%)}	_~	_3,536,756k	_3,537,255k	_{p=0.630 n=6}
_{Parse Time}	_{14.89s (± 0.61%)}	_{14.89s (± 0.23%)}	_~	_14.83s	_14.92s	_{p=0.572 n=6}
_{Bind Time}	_{4.83s (± 0.24%)}	_{4.83s (± 0.52%)}	_~	_4.79s	_4.86s	_{p=0.807 n=6}
_{Check Time}	_{95.95s (± 2.63%)}	_{99.31s (± 2.64%)}	_~	_94.10s	_101.14s	_{p=0.066 n=6}
_{Emit Time}	_{31.32s (±10.75%)}	_{30.35s (± 1.96%)}	_~	_29.16s	_30.74s	_{p=0.810 n=6}
_{Total Time}	_{146.99s (± 3.73%)}	_{149.38s (± 2.14%)}	_~	_143.00s	_151.59s	_{p=0.298 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_320,086	_320,086	_~	_~	_~	_{p=1.000 n=6}
_Types	_140,412	_140,414	_{+2 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{474,322k (± 0.03%)}	_{474,350k (± 0.02%)}	_~	_474,218k	_474,502k	_{p=0.575 n=6}
_{Parse Time}	_{4.34s (± 0.84%)}	_{4.32s (± 0.54%)}	_~	_4.28s	_4.35s	_{p=0.252 n=6}
_{Bind Time}	_{1.78s (± 0.98%)}	_{1.76s (± 1.17%)}	_~	_1.73s	_1.79s	_{p=0.373 n=6}
_{Check Time}	_{20.72s (± 0.23%)}	_{20.71s (± 0.32%)}	_~	_20.62s	_20.79s	_{p=0.469 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{26.83s (± 0.33%)}	_{26.80s (± 0.23%)}	_~	_26.71s	_26.89s	_{p=0.466 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_571,458	_571,458	_~	_~	_~	_{p=1.000 n=6}
_Types	_191,798	_191,798	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{501,863k (± 0.01%)}	_{501,795k (± 0.05%)}	_~	_501,463k	_502,137k	_{p=0.378 n=6}
_{Parse Time}	_{3.43s (± 0.59%)}	_{3.42s (± 1.00%)}	_~	_3.37s	_3.46s	_{p=0.570 n=6}
_{Bind Time}	_{1.24s (± 0.83%)}	_{1.24s (± 0.79%)}	_~	_1.23s	_1.25s	_{p=0.452 n=6}
_{Check Time}	_{20.02s (± 0.38%)}	_{20.42s (± 3.26%)}	_~	_20.01s	_21.68s	_{p=0.230 n=6}
_{Emit Time}	_0.00s	_{0.00s (±244.70%)}	_~	_0.00s	_0.01s	_{p=0.405 n=6}
_{Total Time}	_{24.69s (± 0.34%)}	_{25.08s (± 2.55%)}	_~	_24.65s	_26.28s	_{p=0.170 n=6}

System info unknown

Hosts

node (v18.15.0, x64)

Scenarios

Compiler-Unions - node (v18.15.0, x64)
angular-1 - node (v18.15.0, x64)
mui-docs - node (v18.15.0, x64)
self-build-src - node (v18.15.0, x64)
self-build-src-public-api - node (v18.15.0, x64)
self-compiler - node (v18.15.0, x64)
ts-pre-modules - node (v18.15.0, x64)
vscode - node (v18.15.0, x64)
webpack - node (v18.15.0, x64)
xstate-main - node (v18.15.0, x64)

_Benchmark	_Name	_Iterations
_Current	_pr	₆
_Baseline	_baseline	₆

Developer Information:

Download Benchmarks

typescript-bot · 2025-06-05T01:10:26Z

@jakebailey Here are the results of running the top 400 repos with tsc comparing main and refs/pull/61817/merge:

Everything looks good!

jakebailey · 2026-02-06T06:16:54Z

Failed to look at this properly until now. I am shocked this isn't super breaky?

Renegade334 · 2026-02-06T06:39:56Z

I guess the shared view is often going to appear in a context where its type is inferred, rather than annotated? But yes, somewhat surprising

jakebailey · 2026-02-06T20:37:44Z

I searched github for Atomics.wait, and immediately found places that this will break. Probably going to hold off on this one.

lib: narrow Atomics.wait* target to SharedArrayBuffer views

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jakebailey reopened this Feb 6, 2026

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lib: narrow `Atomics.wait*` target to SharedArrayBuffer views#61817

lib: narrow `Atomics.wait*` target to SharedArrayBuffer views#61817
Renegade334 wants to merge 1 commit intomicrosoft:mainfrom
Renegade334:atomics-explicit-sharedarraybufferview

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