cursor-based SSR, Suspense, out-of-order streaming#8431
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cursor-based SSR, Suspense, out-of-order streaming#8431
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Use-id E2E hang investigation results: The hang occurs for deeply nested component trees (3+ levels with multiple children per level) Root cause identified: When the emit loop's BLOCKED_DIRTY case awaits (via setImmediate or microtask), the triggerCursors microtask from addCursor runs processCursorQueue with unlimited timeBudget: 0. This microtask-driven walk somehow completes the cursor but leaves $renderPromise$ unresolved, causing the emit loop to hang on await this.$renderPromise$ Setting yieldBudget: 0 (no yielding) fixes the use-id hang but breaks projection tests that need async yielding for microtask processing Fix applied: Changed BLOCKED_DIRTY yield from setImmediate (macrotask, ~10ms overhead) to Promise.resolve() (microtask, near-zero overhead). This fixes the O(n) macrotask overhead but doesn't fully resolve the deep nesting hang Defensive fix applied: Added $checkPendingCount$() in processCursorQueue's catch block to prevent hangs when a cursor errors out The use-id E2E test hang is a pre-existing issue on the ssr-cursors branch that needs deeper investigation into the interaction between triggerCursors microtasks and the emit loop's $renderPromise$ handling.
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