René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"CLS store gets reset on the first callback in http scenario","articleBody":"\u003c!--\r\nThank you for reporting an issue.\r\n\r\nThis issue tracker is for bugs and issues found within Node.js core.\r\nIf you require more general support please file an issue on our help\r\nrepo. https://github.com/nodejs/help\r\n\r\n\r\nPlease fill in as much of the template below as you're able.\r\n\r\nVersion: output of `node -v`\r\nPlatform: output of `uname -a` (UNIX), or version and 32 or 64-bit (Windows)\r\nSubsystem: if known, please specify affected core module name\r\n--\u003e\r\n\r\n* **Version**: master\r\n* **Platform**: Linux\r\n* **Subsystem**: async_hooks\r\n\r\n### What steps will reproduce the bug?\r\n\r\nI have been trying to write some new scenarios for AsyncLocalStorage class, as mentioned in https://github.com/nodejs/node/issues/31978, and came across this issue:\r\n\r\n\r\n```js\r\nconst { AsyncLocalStorage } = require('async_hooks');\r\nconst http = require('http')\r\nconst cls = new AsyncLocalStorage();\r\n\r\nconst server = http.createServer((req, res) =\u003e {\r\n  res.write('hello')\r\n  setTimeout(() =\u003e {\r\n    res.end(' world!')\r\n  }, 1000)\r\n})\r\n\r\nserver.listen(12000, () =\u003e {\r\n  cls.run(() =\u003e {\r\n    const req = http.get('http://localhost:12000', (res) =\u003e {\r\n      const store = cls.getStore()\r\n      store.set('foo', '')\r\n      res.on('data', (d) =\u003e { console.log(cls.getStore()) });\r\n    })\r\n    req.end()\r\n  })\r\n})\r\n```\r\n\r\nIn this simple client-server program, the server is sending two chunks of data, forcing the `ondata` handler to be invoked twice.\r\n\r\n### How often does it reproduce? Is there a required condition?\r\n\r\nevery time\r\n\r\n### What is the expected behavior?\r\n\r\nI get an empty Map every time in the ondata callback\r\n\r\n\u003c!--\r\nIf possible please provide textual output instead of screenshots.\r\n--\u003e\r\n\r\n### What do you see instead?\r\n\r\nUnfortunately, the store is `undefined` after the first invocation:\r\n\r\n```trace\r\n$ node foo.js\r\nMap(1) { 'foo' =\u003e '' }\r\nundefined\r\n^C\r\n$\r\n```\r\n\r\n\u003c!--\r\nIf possible please provide textual output instead of screenshots.\r\n--\u003e\r\n\r\n### Additional information\r\n\r\nIf I replace this with a simple timer code, this logic works fine:\r\n\r\n```js\r\nconst { AsyncLocalStorage } = require('async_hooks');\r\nconst cls = new AsyncLocalStorage();\r\n\r\ncls.run(() =\u003e {\r\n  const store = cls.getStore()\r\n  store.set('foo', 'bar')\r\n  setInterval(() =\u003e {\r\n    console.log(cls.getStore().get('foo'))\r\n  }, 1000)\r\n}) \r\n```\r\n\r\n$ node timer.js\r\n```trace\r\nbar\r\nbar\r\nbar\r\nbar\r\n^C\r\n```\r\n\r\n\r\nAm I missing something?\r\n\r\nPing @vdeturckheim \r\n\u003c!--\r\nTell us anything else you think we should know.\r\n--\u003e\r\n","author":{"url":"https://github.com/HarshithaKP","@type":"Person","name":"HarshithaKP"},"datePublished":"2020-03-03T07:23:07.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":7},"url":"https://github.com/32060/node/issues/32060"}