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fix: avoid microtask in flushSync#16394

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Merged

Rich-Harris merged 4 commits intomainfromavoid-microtask-in-flushsync

Jul 16, 2025

Merged

fix: avoid microtask in flushSync#16394

Rich-Harris merged 4 commits intomainfromavoid-microtask-in-flushsync

Jul 16, 2025

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Rich-Harris commentedJul 16, 2025

file this under 'things that don't matter at all in the real world but matter a great deal in benchmarks'

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fix: avoid microtask in flushSync

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Latest commit:282cd94

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github-actionsbot commentedJul 16, 2025

Playground

pnpm add https://pkg.pr.new/svelte@16394

Rich-Harris added2 commits

July 16, 2025 11:25

fix/simplify

eac029c

on second thoughts

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Rich-Harris commentedJul 16, 2025

In case this seems unnecessary:

sbench_create_signals  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼  370.47ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 385.32ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼  160.90ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 173.83mssbench_create_0to1  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 5.50ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 5.54mssbench_create_1to1  time: fastest is b (main)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 20.92ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 20.86ms  gc_time: fastest is b (main)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 2.95ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 2.88mssbench_create_2to1  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 18.23ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 18.39ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 2.95ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 2.97mssbench_create_4to1  time: fastest is b (main)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 16.94ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 16.82ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼  2.91ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 2.99mssbench_create_1000to1  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 15.17ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 15.31ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼  3.03ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 3.13mssbench_create_1to2  time: fastest is b (main)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 10.14ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 10.13ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼  0.75ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 0.78mssbench_create_1to4  time: fastest is b (main)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 8.60ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 8.50ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼    0.55ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 0.63mssbench_create_1to8  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼   6.32ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 6.90mssbench_create_1to1000  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 8.21ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 8.28ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼  0.63ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 0.68mskairo_avoidable_owned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼              496.03ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 1397.77ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼                    35.21ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 679.47mskairo_avoidable_unowned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼            595.58ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 1307.73ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼                    36.39ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 609.89mskairo_broad_owned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼  476.75ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 509.22ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼                   1.93ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 17.15mskairo_broad_unowned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼  473.87ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 508.22ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼                   1.93ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 17.46mskairo_deep_owned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼   205.71ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 228.45ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼                   1.69ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 16.43mskairo_deep_unowned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼  949.68ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 980.03ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼                   2.03ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 17.07mskairo_diamond_owned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼         411.28ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 684.22ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼                   19.78ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 223.92mskairo_diamond_unowned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼        506.73ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 778.16ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼                   19.53ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 222.74mskairo_triangle_owned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼      126.25ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 167.67ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼                   3.43ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 31.46mskairo_triangle_unowned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼    245.34ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 288.21ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼                   3.39ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 32.83mskairo_mux_owned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼  328.86ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 344.89ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼               2.62ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 9.41mskairo_mux_unowned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼  486.95ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 507.78ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼               3.30ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 10.61mskairo_repeated_owned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼        78.36ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 123.92ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼                   2.94ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 34.61mskairo_repeated_unowned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼         75.80ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 122.41ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼                   3.34ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 32.98mskairo_unstable_owned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼      114.68ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 158.05ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼                   3.48ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 33.52mskairo_unstable_unowned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼      129.37ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 173.25ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼                   3.52ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 33.59msmol_bench_owned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼  286.24ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 294.20ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼                  1.03ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 6.22msmol_bench_unowned  time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼  304.55ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 312.96ms  gc_time: fastest is a (avoid-microtask-in-flushsync)    a: ◼◼◼                  0.85ms    b: ◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼◼ 6.57ms