Uploading some modules fails

[lucacasonato]

Currently some file uploads fail with the error with error trying to connect: Connection reset by peer (os error 104). I am not 100% sure what causes this. I assume it is because we are sending requests to S3 too quickly.

Previously we also had issues with DNS rate limiting. I was able to mostly resolve this by introducing a upload rate limit of 6 files a second.

I think both issues could be tackled by reusing the HTTP connections to S3. This is something that needs to be fixed upstream in Deno. It should also increase the overall speed of uploading, because many uploads can be multiplexed onto a single HTTP/2 connection and the client side rate limit can be removed.

[lucacasonato]

Status update: Deno now uses a connection pool (single reqwest client), but this uncovered an issue with reqwests http/2 connection pooling implementation: seanmonstar/reqwest#976

[lucacasonato]

I am going to remove the high priority flag, because this issue occurs very, very rarely now.