Gnat
A nats.io client for elixir. The goals of the project are resiliency, performance, and ease of use.
Usage
{:ok, gnat} = Gnat.start_link(%{host: '127.0.0.1', port: 4222})
# Or if the server requires TLS you can start a connection with:
# {:ok, gnat} = Gnat.start_link(%{host: '127.0.0.1', port: 4222, tls: true})
{:ok, subscription} = Gnat.sub(gnat, self(), "pawnee.*")
:ok = Gnat.pub(gnat, "pawnee.news", "Leslie Knope recalled from city council (Jammed)")
receive do
{:msg, %{body: body, topic: "pawnee.news", reply_to: nil}} ->
IO.puts(body)
end
Benchmarks
Part of the motivation for building this library is to get better performance.
To this end I've started a bench.exs script that we can use to check our performance.
As of this commit the most recent numbers from running on my macbook pro are:
| ips | average | deviation | median | |
|---|---|---|---|---|
| parse-128 | 81.86 K | 12.22 μs | ±177.12% | 11.00 μs |
| pub - 128 | 146.22 K | 6.84 μs | ±450.03% | 6.00 μs |
| sub-unsub-pub16 | 9.06 K | 110.37 μs | ±68.61% | 102.00 μs |
| req-reply-4 | 5.67 K | 176.45 μs | ±19.81% | 165.00 μs |
These benchmarks all show single-actor performance with a locally running gnats server. Running 32 client actors on an 8-core ubuntu server sending requests to another 8-core ubuntu server running 2 gnat subscriber actors we achieved:
- 19,920 requests/sec
- 90th % latency of 2.2ms
see details in the performance issue
Development
To run the tests the typical mix test will run all the basic unit tests.
You can also run the multi_server set of tests that test connectivity to different
gnatsd with different configurations. You can run these with mix test --only multi_server.
There are also some property-based tests that generate a lot of test cases.
You can tune how many test cases by setting the environment variable N=200 mix test --only property (default it 100).
For more details you can look at how Travis runs these things in the CI flow.