stream: avoid duplicated endReadableNT scheduling - #65310
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Calling read() on an ended stream multiple times before the microtask queue drains scheduled one endReadableNT tick per call, as the only guard was endEmitted, which is set inside the tick itself. A hello-world HTTP server was scheduling it four times per request while dumping the unread request body. Introduce a kEndScheduled flag armed when the tick is scheduled and cleared when it runs. Clearing it unconditionally matters for reused sockets: undestroy() resets endEmitted through the state descriptors but cannot reach this flag, and a stale value would block the 'end' event after a net.Socket reconnect.
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jasnell
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Aug 15, 2026
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Calling read() on an ended stream multiple times before the microtask queue drains scheduled one endReadableNT tick per call, since the only guard (endEmitted) is set inside the tick itself. A hello-world HTTP server was scheduling it four times per request while dumping the unread request body.
Add a kEndScheduled flag, armed on scheduling and cleared when the tick runs. It must be cleared unconditionally: undestroy() resets endEmitted through the state descriptors but cannot reach this flag, and a stale value would block 'end' after a net.Socket reconnect.
Benchmarks vs main:
streams/finished.jsreadable +10.45% (99.9% confidence), no significant regressions across the streams suite; ~+1-3% on HTTP server benchmarks (10 → 7 nextTicks per request).