yada-async-test

Testing an async endpoint with Yada

What I expect from an async endpoint:

• Other endpoints remain responsive no matter how many request to async endpoints are being processed.

How to reproduce?

• Clone this repository
• In a terminal sesssion: cd yada-async-test/edge
• boot dev and wait for a webserver to be started at port 3010
• Visit The Swagger UI in a browser. There you'll see two endpoints, async and hello.
• In another terminal session: cd yada-async-test/external.
• lein repl
• (dev)
• (go) and wait for a webserver to be started at port 3000. This service has one endpoint called example which will wait 5 seconds before it returns a response.

Now for the test:

• In another browser tab, visit http://localhost:3010/api/hello while having a Network tab open in devtools so you can see the response time. On my machine this was about 6ms. Click preserve log, so you can compare requests when you hit refresh.

• In the The Swagger UI fire 20 request. Meanwhile, refresh the tab with the call to api/hello a couple of times and notice how it becomes less responsive. On my machine it sometimes takes a couple of seconds before a request comes back. This is different from my expectation:

Solution

ab -n 20 -c 20 -v 10 -H 'Accept: application/json' 'http://localhost:3010/api/async'
ab -n 20 -c 20 -v 999 -H 'Accept: text/plain' 'http://localhost:3010/api/hello'

The problem was that there is a maximum number of concurrent requests to the same domain in browsers. Use a different tool like Apache Bench. Thanks to thegeez for pointing me to the solution.