loom VS coyote

It's more accurate to say Loom is [a particular type of] continuations in the JVM, which can be used to implement green threads / fibers.

You can see the implementation of VirtualThread here: https://github.com/openjdk/loom/blob/fibers/src/java.base/sh...

This uses the internal 'one-shot delimited continuation': https://github.com/openjdk/loom/blob/fibers/src/java.base/sh...

So, at least in principle, there is scope for other styles of concurrency to be implemented over this.

Loom is actively developed https://github.com/openjdk/loom

Currently the Thread public constructor defaults to platform threads to be fully backwards compatible. So all libraries must be updated to support the new model.

I've been casually following the repo ( https://github.com/openjdk/loom ) and the mailing list ( https://mail.openjdk.java.net/mailman/listinfo/loom-dev ) over the last 18 months or so, and it definitely appears that things are ramping up as of late. The implication (as I see it) is that they are relatively happy with the general design are and are at the point where they want help from experts in the various areas of the JDK (GC, Debugging, etc) to make sure that their pieces play well with Loom.

https://github.com/openjdk/loom/blob/fibers/src/java.base/share/classes/sun/nio/ch/NioSocketImpl.java#L177

[1] https://github.com/openjdk/loom/blob/fibers/src/java.base/share/classes/java/lang/VirtualThread.java#L933

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...