René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"stream/iter: share() does not discard upstream results with \"drop-newest\"","articleBody":"### Version\n\nmain\n\n### Platform\n\n```text\nmacOS 26.5.2\n```\n\n### Subsystem\n\nstream\n\n### What steps will reproduce the bug?\n\n```js\nimport { share } from 'node:stream/iter';\n\nasync function* source() {\n  for (let i = 0; i \u003c 4; i++)\n    yield [new TextEncoder().encode(`${i}`)];\n}\n\nconst shared = share(source(), {\n  highWaterMark: 2,\n  backpressure: 'drop-newest',\n});\n\nconst fast = shared.pull();\nconst slow = shared.pull();\n\nconst read = async (stream) =\u003e (await Array.fromAsync(stream))\n  .flat()\n  .map((chunk) =\u003e new TextDecoder().decode(chunk));\n\nconsole.log('fast:', await read(fast));\nconsole.log('bufferSize:', shared.bufferSize);\nconsole.log('slow:', await read(slow));\n\n```\n\n### How often does it reproduce? Is there a required condition?\n\nAlways\n\n### What is the expected behavior? Why is that the expected behavior?\n\n```console\nfast: [ '0', '1' ]\nbufferSize: 2\nslow: [ '0', '1' ]\n```\n\nOnce the two-slot buffer is full, upstream results `'2'` and `'3'` are discarded under `\"drop-newest\"`.\nNeither consumer receives them, and the buffer never exceeds `highWaterMark`.\n\nFrom [§13.2.2 — “Share buffering and backpressure”](https://stream-iter.jasnell.me/#share-backpressure)\n\u003e With `\"drop-newest\"`, the upstream pull result is discarded.\n\n### What do you see instead?\n\n```console\nfast: [ '0', '1', '2', '3' ]\nbufferSize: 4\nslow: [ '0', '1', '2', '3' ]\n```\n\nThe buffer grows to four entries despite `highWaterMark: 2`, and the stalled consumer eventually receives every batch\n\n### Additional information\n\n_No response_","author":{"url":"https://github.com/trivikr","@type":"Person","name":"trivikr"},"datePublished":"2026-07-11T02:23:25.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/64416/node/issues/64416"}