BlockHound VS coyote

There is a great tool called Blockhound we can use to detect if/when we have a blocking call in our application. This way, we can ensure that we don't break the non-blocking nature of our application by mistake while developing new features. Setting it up is fairly straightforward.

There's even a test library to detect them: https://github.com/reactor/BlockHound

One of the talks in my current portfolio is Migrating from Imperative to Reactive. The talk is based on a demo migrating from Spring WebMVC to Spring WebFlux in a step-by-step approach. One of the steps involves installing BlockHound: it allows to check whether a blocking call occurs in a thread it shouldn't happen and throws an exception at runtime when it happens.

The first step is to make the application compatible with GraalVM. We need to remove Blockhound from the code. Blockhound allows verifying that no blocking code runs in unwanted places. It's a Java agent that requires a JDK, not a JRE. It's great for a demo, but it has nothing to do with a production application.

ex: https://github.com/microsoft/coyote/blob/main/Samples/Accoun...

Microsoft has a library/tool called Coyote* that helps with testing distributed systems; you can write tests/specifications, Coyote will systematically explore nondeterminism in your system and check if your tests still pass. If there's a failure, it'll show the sequence of events that led to the failing test.

I started a project to implement Raft with a KV-store on top, similar to the article, meaning to use Coyote to test it; I didn't get that far before losing interest, though. It's reassuring to read that it took Phil several months to write the code in the post, it's good to know that this is a decidedly nontrivial problem.

* https://github.com/microsoft/coyote

Something like coyote by MS?

If you're looking for similar concurrency testing in the dotnet world, checkout Coyote:

https://microsoft.github.io/coyote/

https://innovation.microsoft.com/en-us/exploring-project-coy...

MS provides a framework for testing for concurrency issues: https://microsoft.github.io/coyote/.

I suggest you try Microsoft Coyote

Visualizations do help a lot when model checkers and concurrency schedule exploration tools like Coyote find bugs. Coyote include the ability to visualize the traces if you express your concurrency using actors (see https://microsoft.github.io/coyote/#concepts/actors/state-ma...)

It also allows you to implement your own "logger" through which you can emit enough information to construct some cool visualizations. I had a lot of fun working on visualizing an implementation of Paxos using Coyote (then P#) (screenshot at https://ibb.co/TTk2hYb)

If curious, you can learn more in the Coyote website https://microsoft.github.io/coyote

Hi HN,

The tweet links to a couple of tutorials showing how to test an extremely simple CRUD service using Coyote to find concurrency bugs. Developers write simple unit tests whose concurrency is explored by Coyote to find bugs. You might be surprised to learn how we can write a number of interesting concurrency tests for even the simplest of CRUD services.

https://microsoft.github.io/coyote/#tutorials/first-concurre...