Feb 16, 2021

Grouping Quarkus extension tests for faster execution

Testing is a substantial ingredient of software quality. Projects producing Quarkus extensions are not an exception. While testing on traditional JVMs is rather fast and well understood, testing GraalVM native executables brings new challenges, especially because it takes long: It is one or more minutes for common test projects that we have in Camel Quarkus. Multiply it with our ~300 extensions and you end up with tens of hours for a single pass of the CI. Let’s discuss some ways how to speed up the native testing, esp. by merging several test modules into a single test module.

Quarkus extension testing: An intro

(Feel free to skip this if you know well how Quarkus extension tests work.)

Here we primarily speak about integration tests that typically consist of a small application in src/main and a couple of tests in src/test that validate the behavior of the application. The test module is supposed to depend on the tested extension and the application is supposed to make use of that extension. As an example, look at e.g. the ActiveMQ test in Camel Quarkus source tree.

There are test classes of two kinds in src/test/java:

  1. Ending with Test - those are for testing in JVM mode

  2. Ending with IT - for testing in native mode.

While the JVM tests are run in the same JVM as the application under test, the native tests are run in a process separate from the application. This is because in the latter case the application is compiled to native executable and that executable is run standalone (without any JVM).

For this very reason, native tests must communicate with the tested application via network (or filesystem, etc.). In JVM tests, there are a couple of other options, like directly injecting beans via CDI. We avoid using this in Camel Quarkus, because our *IT tests inherit from their *Test counterparts so that JVM tests generally check the same functionality as native tests.

As we have pointed out already, compiling the test application to native executable takes a substantial portion of the overall testing time.

Which options are there to speed it up?

Parallelize the execution

Of course Quarkus integration tests can be run in parallel on multiple worker nodes. It is easy to implement in environments like GitHub Actions and indeed, we are keen on utilizing it in Camel Quarkus.

The not-so-good news is that GitHub Actions limits the number of concurrent jobs to 20 (in the free tier at least). That currently makes our pull request verification to take around two hours which is still outside of my comfort zone.

What other optimizations can be implemented?

Incremental testing

Falko Modler works on introducing Gitflow incremental builder to Quarkus. While it has tremendous potential, it is still work in progress. Let’s wait and see how well it goes in Quarkus.

Grouping of extension tests

This is actually the idea I wanted this blog post to be about 🙂.

The core hypothesis of this approach is that the native compilation of an application consisting of JARs A, B and C generally takes less time than the sum of compilation times of two separate applications consisting of (1) A and B and (2) A and C respectively.

Here, A is thought to be some common base that is found in both (1) and (2). We typically have this situation in our integration tests - they all contain quarkus-core, camel-quarkus-core, quarkus-resteasy (plus all their transitive dependencies) and last but not least all the Java runtime classes.

We assume that especially for test modules, whose dependency sets differ by just a few small JARs, "merging" them together into a single module may save some native compilation time.

We actually did this since a log time, e.g. with our AWS extensions, but nobody bothered to gather some real numbers to confirm or deny the hypothesis.

What could go wrong?

Before I show you the benchmarks, let’s discuss what are the risks and drawbacks of test grouping.

James pointed out once that "extensions may fix each other". If extension A forgets to register some class for reflection that extension B does register, then, when the two are used together in an application, B provides the necessary config and the tests pass. However, if A would be alone without B in a test application the tests would fail because the registration for reflection is missing.

For this reason, hard coding multiple extensions' tests into a single test module might be risky. Ideally, it should be possible to have both: the faster grouped setup for pull request verification and the slower but methodologically cleaner isolated setup for proper nightly/weekly/pre-release verification.

Semi-automatic grouping

I have recently split a couple of AWS tests properly and I have also put some tooling in place that generates the grouped module semi-automatically.

In that way it is easy to run the tests both in isolation and grouped whichever suits better for the given use case.

And thanks to this setup, it is also quite easy to compare the duration of the grouped and isolated execution.


My measurements were not perfectly scientific, because I performed just a single round and I had other programs running.

My machine:

  • AMD Ryzen Threadripper 1920X, 12 cores @ 2162 MHz

  • 64 GB RAM

  • HDD SSD Samsung 970 EVO

  • Fedora 31

Here are the numbers:

Grouping vs. duration


Duration (sec)





The time difference is about 5 minutes and it might be a bit more on slowish CI worker nodes. That’s definitely worth the effort!

Possible next step

We are planning to add more AWS tests in the near future. It will be interesting to see how the grouped module scales with the number of tested extensions.

Steps to reproduce

export GRAALVM_HOME=...
$ $GRAALVM_HOME/bin/java -version
openjdk version "11.0.10" 2021-01-19
OpenJDK Runtime Environment GraalVM CE 20.3.1 (build 11.0.10+8-jvmci-20.3-b09)
OpenJDK 64-Bit Server VM GraalVM CE 20.3.1 (build 11.0.10+8-jvmci-20.3-b09, mixed mode, sharing)

# clone Camel Quarkus
$ git clone git@github.com:apache/camel-quarkus.git
$ cd camel-quarkus
$ CQ_HOME=$(pwd)

# This is the revision I worked with:
$ git reset --hard 83e5c768b6196de7a7fb04990c3a40e2a22d24f7

# Build the whole tree without tests
$ mvn clean install -Dquickly

# Run the isolated tests, both JVM and native
$ cd $CQ_HOME/integration-tests-aws2
$ mvn clean verify -Pnative
# record the duration reported by Maven

# Run the grouped tests, both JVM and native
$ cd $CQ_HOME/integration-tests/aws2-grouped
$ mvn clean verify -Pnative
# record the duration reported by Maven


Thanks for reading and stay tuned for more posts about Quarkus, GraalVM, Apache Camel and mvnd!

Edit this post

Related posts