[Bug 1.25.1] (Deno.serve) - Only handles one request at a time

[sagea]

Description

The new Deno.serve method only appears to be allowing one request at a time.

I have two examples below:

1. Using Deno.serve (Runs all requests synchronously)
2. Using std HTTP serve (Runs all requests in parallel)

Example (Using Deno.serve)

Command: RUST_BACKTRACE=full deno run -A --unstable serve-test.ts

Source:

let active = 0;
const sleep = (time: number) => new Promise(r => setTimeout(r, time));
const start = (pathname: string) => {
  active++;
  console.log(`⏰ Request received  ${pathname}  | Total Active: ${active}`)
};
const end = (pathname: string) => {
  active--;
  console.log(`✅ Request completed ${pathname}  | Total Active: ${active}`);
}

const handler: Deno.ServeHandler = async (event) => {
  const pathname = new URL(event.url).pathname;
  start(pathname);
  await sleep(2000);
  try {
    return new Response('done');
  } finally {
    end(pathname);
  }
};

Deno.serve(
  {
    handler,
    port: 9999,
    onListen({ hostname, port }) {
      console.log(`Server Started... http://${hostname}:${port}/`);
    }
  } 
)

Example (Using std/http/server)

Command: RUST_BACKTRACE=full deno run -A serve-test.ts

Source:

import { serve } from "https://deno.land/std@0.154.0/http/server.ts";

let active = 0;
const sleep = (time: number) => new Promise(r => setTimeout(r, time));
const start = (pathname: string) => {
  active++;
  console.log(`⏰ Request received  ${pathname}  | Total Active: ${active}`)
};
const end = (pathname: string) => {
  active--;
  console.log(`✅ Request completed ${pathname}  | Total Active: ${active}`);
}

const handler: Deno.ServeHandler = async (event) => {
  const pathname = new URL(event.url).pathname;
  start(pathname);
  await sleep(2000);
  try {
    return new Response('done');
  } finally {
    end(pathname);
  }
};

serve(
  handler,
  {
    port: 9999,
    onListen({ hostname, port }) {
      console.log(`Server Started... http://${hostname}:${port}/`);
    }
  } 
)

[littledivy]

Thanks for the detailed reproduction. I can confirm that #15852 fixes the issue:

Screen.Recording.2022-09-11.at.9.40.11.AM.mov

[sagea]

@littledivy Thanks for the fix!