How can I increase max concurrent request of Phoenix on fly.io?

nallwhy · June 25, 2022, 3:21am

I made a toy project that provides a simple API for testing.

This project is served via fly.io.
Here is my fly.io configuration below. I configured services.concurrency.hard_limit to 10000 and services.concurrency.type to requests following max concurrency can not be greater than 300 - #4 by fxsjy.

github.com

nallwhy/json_corp/blob/main/fly.toml

# fly.toml file generated for json-corp on 2022-06-03T02:31:32+09:00

app = "json-corp"

kill_signal = "SIGINT"
kill_timeout = 5
processes = []

[build]
  builder = "heroku/buildpacks:20"
  buildpacks = ["https://cnb-shim.herokuapp.com/v1/hashnuke/elixir"]

[env]
  PORT = "8080"

[experimental]
  allowed_public_ports = []
  auto_rollback = true

[[services]]

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I wanted to do a load test for this project. Below is the code I used for the load test.

github.com

nallwhy/test_api/blob/main/notebooks/load_test.livemd

# Load Test

```elixir
Mix.install([:chaperon, :req])
```

## Section

<!-- livebook:{"branch_parent_index":0} -->

## With Req

```elixir
require Logger

count = 500
timeout = 2

url = "https://json.media/test_api/api?timeout=#{timeout}"
# url = "http://localhost:4000/test_api/api?timeout=#{timeout}"

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When I run the code that tests with req, about 200 requests returns ok and other requests returns error %Mint.TransportError{reason: :closed}.

How can I increase max concurrent request over 200?

kurt · June 25, 2022, 8:25pm

These kinds of load tests are hard. We won’t allow that many requests from a single IP address. So the app may not be the bottleneck.

To do a proper load test, you’ll need to generate traffic from multiple sources in multiple regions.

Or, if you want to test your app directly, run a load test over the private network directly against its IP.

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How can I increase max concurrent request of Phoenix on fly.io?

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