Timeout fails for items in browser concurrency queue

Most browsers have a limit of 6 concurrent connections per origin, after which they queue requests. I’m using AwsS3 Uploader. If user uploads 7 files and 6 of them are large enough to take more than 30 seconds to transfer, the 7th upload gets canceled due to timeout, as its first progress event is only triggered after one of the other files is finished.

This behavior doesn’t occur with Tus Uploader.

Tested with 0.29.0 versions of @uppy/core, @uppy/aws-s3 and @uppy/tus.

Could we delay setting the aliveTimer from XHRUpload until XHR has left the browser queue (e.g. after a minimal amount of bytes were loaded on progress event)? It seems we couldn’t use the uploadStarted flag because it is set as soon as the xhr has its send() method invoked.

[leods92]

I agree with your approach, @davilima6. This probably also fixes #1188 because the timeout would never happen unless progress has been reported. I think it makes a lot of sense to only timeout after something successful started.

Do you know what happens if the server rejects a request after the connection is opened? Is the error properly handled by Uppy? If yes, I think it’s a solid solution.

[davilima6]

Update: 0.29.1 was released 6 days ago including this fix. Thanks!