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perf(@angular/build): avoid reading external component stylesheets twice - #34434
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alan-agius4 merged 2 commits intoOct 21, 2026
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- Skip calling `this.readFile(filename)` in `host.readResource(filename)` when `!hasTemplateExtension(filename)` so external component stylesheets (`styleUrl` / `styleUrls`) are not read from disk on the Angular compiler worker thread and serialized over the worker `MessagePort` only to be ignored by `transformStylesheet`. - Only short-circuit empty `data` in `host.transformResource(data, context)` for inline styles (`!context.resourceFile`) so external stylesheets still proceed to `transformStylesheet`.
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October 21, 2026 06:44
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This pull request optimizes resource loading and transformation in the Angular compiler host. Specifically, readResource is updated to only read template files, bypassing external stylesheets which are bundled during transformResource. Additionally, transformResource is adjusted to only short-circuit empty inline styles, ensuring empty external stylesheets are still processed. Unit tests have been added to verify these changes. As there are no review comments, I have no feedback to provide.
clydin
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Oct 21, 2026
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host.readResource(filename), return''directly when!hasTemplateExtension(filename)instead of reading the external stylesheet file from disk on the Angular compiler worker thread and serializing its contents over the workerMessagePort, sincetransformStylesheetignoresdatawhenstylesheetFileis provided and reads/bundles the file viastylesheetBundler.bundleFile(stylesheetFile).host.transformResource(data, context), only short-circuit emptydatafor inline styles (!context.resourceFile && data.trim().length === 0) so external stylesheets proceed tohostOptions.transformStylesheet.