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Quarkus demo: Quartz scheduling

This is an application demoing a clustered scheduler. It exposes a REST API tasks to visualize the executed jobs which run every 10 seconds.

Requirements

To compile and run this demo you will need:

  • JDK 1.8+
  • GraalVM

In addition, you will need either a PostgreSQL database, or Docker to run one.

Configuring GraalVM and JDK 1.8+

Make sure that both the GRAALVM_HOME and JAVA_HOME environment variables have been set, and that a JDK 1.8+ java command is on the path.

See the Building a Native Executable guide for help setting up your environment.

Building the demo

Launch the Maven build on the checked out sources of this demo:

./mvnw install

Running the demo

Prepare a PostgreSQL instance

Make sure you have a PostgreSQL instance running. To set up a PostgreSQL database with Docker:

docker-compose up postgres

Connection properties for the Agroal datasource, and Quartz are defined in the standard Quarkus configuration file, src/main/resources/application.properties.

Live coding with Quarkus

The Maven Quarkus plugin provides a development mode that supports live coding. To try this out:

mvn compile quarkus:dev

In this mode you can make changes to the code and have the changes immediately applied, by just refreshing your browser.

Run Quarkus in JVM mode

When you're done iterating in developer mode, you can run the application as a conventional jar file.

First compile it:

./mvnw install

Note that running this command will start a PostgreSQL instance and run the tests. To skip tests use the command below

./mvnw install -DskipTests

Then run the application with:

docker-compose up --scale tasks=2 --scale nginx=1

To start two instances of single instance of the application along side the nginx load balancer.

Run Quarkus as a native application

You can also create a native executable from this application without making any source code changes. A native executable removes the dependency on the JVM: everything needed to run the application on the target platform is included in the executable, allowing the application to run with minimal resource overhead.

Compiling a native executable takes a bit longer, as GraalVM performs additional steps to remove unnecessary codepaths. Use the native profile to compile a native executable:

./mvnw install -Dnative

After getting a cup of coffee, you'll be able to run this binary directly:

./target/quartz-quickstart-1.0-SNAPSHOT-runner

Please brace yourself: don't choke on that fresh cup of coffee you just got.

Now observe the time it took to boot, and remember: that time was mostly spent to migrate the quartz tables in your database.

Visualize created tasks

curl http://localhost:8080/tasks

Have fun, and join the team of contributors!