fix(@angular/ssr): avoid retaining rendered HTML in memory post-request #31278
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The previous implementation for server-side rendering could lead to memory leaks where the rendered HTML content was not properly garbage-collected after the HTTP request was fulfilled. This was caused by inefficiencies in the critical CSS caching and how the response stream was handled. This commit addresses the issue by: 1. Refactoring the `criticalCssLRUCache` to store `Uint8Array` directly and use a more robust caching strategy. 2. Using the request URL as the cache key to prevent storing multiple cache entries for the same resource. 3. Ensuring the response stream controller enqueues the final HTML as a `Uint8Array`, avoiding unnecessary string conversions and dangling references. These changes prevent the SSR response from being retained in memory, improving the stability and performance of the server. Closes angular#31277
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The previous implementation for server-side rendering could lead to memory leaks where the rendered HTML content was not properly garbage-collected after the HTTP request was fulfilled.
This was caused by inefficiencies in the critical CSS caching and how the response stream was handled. This commit addresses the issue by:
criticalCssLRUCacheto storeUint8Arraydirectly and use a more robust caching strategy.Uint8Array, avoiding unnecessary string conversions and dangling references.These changes prevent the SSR response from being retained in memory, improving the stability and performance of the server.
Closes #31277