Fix incompatibility with New Relic

[lukeupup]

Fix #345

[lukeupup]

Didn't change 1 to 0, though 0 looks also work

[sindresorhus]

I don't remember why it's 1 and not 0.

@sholladay Do you?

[sindresorhus]

If 0 is fine, we can just remove the argument altogether.

[szmarczak]

@sindresorhus #118

[szmarczak]

I'm not sure if Chrome replaces 0 with 1 or no. In that case it wouldn't matter.

[sholladay]

I don't think you need to wrap the for loop in the new promise, just the fetch.

[sindresorhus]

Please report this to New Relic and then update the code comment with a bug ID.

[sindresorhus]

Not sure what you mean by "parallel promise". Would be great if you could be more specific.

[sindresorhus]

Can you check if queueMicrotask() works?

[sholladay]

@lukeupup I pushed some changes to make the code a bit cleaner. I'm hoping it will still work but have no way to test it. Can you please check?

[lukeupup]

@lukeupup I pushed some changes to make the code a bit cleaner. I'm hoping it will still work but have no way to test it. Can you please check?

@sholladay Amazing, it works indeed on our environment! Although I don't really understand how new relic treat delay and Promise.resolve differently... Not sure if @smblee can see this thread, but it would be better to invite him to have some test as well. If it also works, I think we can solve the problem as you've submitted. Thanks a lot!

[szmarczak]

@lukeupup In case you missed this: #351 (comment)

[smblee]

Just catching up on this thread - we switched to axios for the time being but i'll give this a shot!

[sholladay]

My theory is that the bug has something to do with the fact that delay() first schedules a callback in the task queue and then after that fires it schedules a callback in the job (microtask) queue. Doing one or the other is normal but combined it's pretty unusual so I figure that may be a situation that New Relic's code isn't handling well. It happens because delay() is using both setTimeout() and a promise.

• https://jakearchibald.com/2015/tasks-microtasks-queues-and-schedules/
• https://careersjs.com/magazine/javascript-job-queue-microtask/

I don't see a clean way to use queueMicrotask() here as the code is async. We'd have to wrap queueMicrotask() in a promise, which would effectively queue two microtasks. Seems pointless. That said, I updated the code to use await Promise.resolve(), which is very similar to queueMicrotask().

BTW, I also updated AVA to reduce the amount of noisy console logs during testing.

I think this PR is ready to merge, assuming it works for @smblee.

[lukeupup]

@sholladay This looks convincing. So let's look forward to the verification result from @smblee . Is there anything I should do before we can merge the code?

[smblee]

I can confirm that this definitely addresses it! Thanks!