Probably related to diesel -> Weird Rust / Hyper / Async behaviour. Why ??

[goriunov]

Setup

Versions

• Rust: 1.30
• Diesel: latest
• Database: PG 10
• Operating System Arch linux

Feature Flags

• diesel: PG r2d2

Problem Description

https://www.reddit.com/r/rust/comments/9ulbj3/weird_rust_hyper_async_behaviour_why/

Video shows everything, i have run multiple times and have gotten that this happens mostly on diesel::insert_into execution.

Steps to reproduce

Check out my repo https://github.com/goriunov/rust-test you can find a comment in code in main.rs

      // uncomment next line to speed up everything
      // println!("Print me");

try running with and without println!("Print me"); line and then bench mark with wrk for example

wrk -t1 -c100 -d10s --latency http://127.0.0.1:3000

Checklist

• I have already looked over the issue tracker for similar issues.
• This issue can be reproduced on Rust's stable channel. (Your issue will be
  closed if this is not the case)

Thank you very much :)