fix(@angular/build): prevent concurrent stylesheet bundling esbuild context leaks#33318
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This pull request introduces request deduplication and write tracking to the Cache class to handle concurrent getOrCreate calls safely, alongside improvements to BundlerContext to manage active bundle promises and disposal. The review feedback highlights a potential race condition in Cache.getOrCreate where an active request might be incorrectly deleted after an await gap, a failing assertion in the new unit tests regarding promise resolution after a cache override, and a potential memory leak due to #writeCounts entries never being cleaned up.
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…ontext leaks When multiple components in the same file define identical inline styles, concurrent calls to the stylesheet bundler invoke Cache.getOrCreate concurrently with the same key. Because getOrCreate is not concurrency-safe, multiple BundlerContext instances are created. Additionally, if multiple bundle() requests occur concurrently on a BundlerContext when the esbuild context is not yet initialized, they both invoke context(), causing one to overwrite and leak the other. Leaked esbuild contexts keep the Node event loop active forever, hanging the test runner. Resolve the Cache race by using an internal Map of in-flight promises to share the same active request, along with a version counter to detect mid-flight writes and safely retry. Resolve the BundlerContext race by memoizing and sharing the active performBundle promise. Fixes angular#33317
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When multiple components in the same file define identical inline styles, concurrent calls to the stylesheet bundler invoke Cache.getOrCreate concurrently with the same key. Because getOrCreate is not concurrency-safe, multiple BundlerContext instances are created.
Additionally, if multiple bundle() requests occur concurrently on a BundlerContext when the esbuild context is not yet initialized, they both invoke context(), causing one to overwrite and leak the other. Leaked esbuild contexts keep the Node event loop active forever, hanging the test runner.
Resolve the Cache race by using an internal Map of in-flight promises to share the same active request, along with a version counter to detect mid-flight writes and safely retry. Resolve the BundlerContext race by memoizing and sharing the active performBundle promise.
Fixes #33317