fetch based library (ky), randomly returns empty string instead of actual body (json)

[dimonnwc3]

What version of Bun is running?

1.0.10+d85bd49d8

What platform is your computer?

Darwin 23.1.0 arm64 arm

What steps can reproduce the bug?

run this code with bun run

import ky from "ky"

setInterval(async () => {
  const data = await ky(`https://dummyjson.com/products`).json()

  if (!data) {
    console.log("no data")
    console.log(data)
  }
}, 500)

wait for 1 minute, it will print randomly "no data" into the console, meaning that some response bodies are empty string

What is the expected behavior?

I expect to get correct response every time I do request

What do you see instead?

I see empty string in response body

Additional information

same code is running in node v18.15.0 returning consistent results

[Electroid]

Did you notice this after upgrading Bun recently? Or did you just run into this

[dimonnwc3]

just run into this randomly

[liz3]

@dimonnwc3 @Electroid #6468 fixes this whenver it gets merged, just confirmed its because ky uses response.clone() internally and that is currently not handled correctly

[liz3]

The issue is a race condition whether the internal network process received the entire body payload before resolving the initial fetch promise, if yes the body is correctly copied and all is good, if data is still coming in the internal body state is locked leading to the clone just having a empty body.

[BrennanColberg]

Experiencing this Response.clone() bug as well with https://www.npmjs.com/package/openapi-fetch.

[liz3]

The pr would be ready for final review and merge(if it passes review) but the maintainers don't prioritize such bug fixes(api compliance) sadly over adding new features because its a "bigger change", so i cant give you a estimate.

[BrennanColberg]

No problem! I've worked around it for now by just replacing response.clone() with response in that library via a well-documented postinstall script, which is unblocking in my use case (do not try this at home)

[dangeredwolf]

I am experiencing this bug because I was using clone() in my own code to prevent "Error: Body already used" when initially calling .text() (to perform cryptographic verification) and later in the code calling .json().

Simplest way to trigger the bug as of Bun v1.0.25 (latest as of time of writing)

const server = Bun.serve({
  fetch: async (req) => {
    console.log(await (await req.clone()).text()) // This is empty instead of containing the body text
    console.log(await req.text()) // Contains the actual body, but now you can't call .text(), .json(), etc. again
  },
});

This looks awfully similar to #913 which was apparently fixed, but does not seem to be. Is this actually a regression of that?

Edit: Turns out this is the same underlying issue as #6348 actually

[Electroid]

Duplicate of #6348

[Electroid]

(We fill fix this)