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WebKit: skip eager timezone prewarm in VM::VM (1.3.14 startup regression) - #35258

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WebKit: skip eager timezone prewarm in VM::VM (1.3.14 startup regression)#35258
robobun wants to merge 3 commits into
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farm/91fe31b9/webkit-defer-tz-prewarm

WebKit: bump to 9bded08f48 (skip eager timezone prewarm in VM::VM)

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Claude / Claude Code Review completed Jul 23, 2026 in 13m 3s

Code review found 1 potential issue

Found 2 candidates, confirmed 1. See review comments for details.

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🔴 Important 0
🟡 Nit 1
🟣 Pre-existing 0
Severity File:Line Issue
🟡 Nit test/js/web/intl/intl.test.ts:331 Main-thread probe() pre-warms the process-global timezone cache before Workers can race

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Check warning on line 331 in test/js/web/intl/intl.test.ts

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@claude claude / Claude Code Review

Main-thread probe() pre-warms the process-global timezone cache before Workers can race

In `[probe(), ...await Promise.all(workers)]`, array elements evaluate left-to-right, so `probe()` runs synchronously on the main thread's already-constructed VM *before* the `await` yields — while the 8 Workers are still spinning up threads and fresh VMs. The main thread therefore almost deterministically wins the process-global `std::call_once` for `initializeAvailableTimeZones`, so the Workers observe an already-filled cache instead of racing on cold init. Consider `const wr = await Promise.a