Going AOT

As stated in Quarkus documentation, we try to build a native executable running :

mvn install -Dnative

Which will lead to a few errors, starting with :

Error: Detected a started Thread in the image heap. Thread name: Java2D Disposer. Threads running in the image generator are no longer running at image runtime. If these objects should not be stored in the image heap, you can use

    '--trace-object-instantiation=java.lang.Thread'

It is often possible to achieve AOT compatibility tweaking a few parameters. GraalVM is very good at providing hints on what to do (like in the example above). There are also a few techniques helping to configure the application in order to create a native image (for instance the tracing agent).

Generally speaking the framework we are using, Venus, is already configured for AOT. Unfortunately not all modules are native ready. In particular the mod-fop extension it is not easy to be built with GraalVM.

This is partly explained in a Quarkus Camel issue about pdfbox 2.

Our goal is to show a demo for the mixed JIT to AOT conversion approach.

In this scenario we modify the applicatin to run both in JIT and AOT mode, but in latter the PDF document feature will be disabled.

We will achieve with three simple modifications.

1. Update the maven pom file

The main reason why we get the error is that GraalVM fails on this dependency at build time :

    <dependency>
      <groupId>org.fugerit.java</groupId>
      <artifactId>fj-doc-mod-fop</artifactId>
      <exclusions>
        <exclusion>
          <groupId>xml-apis</groupId>
          <artifactId>xml-apis</artifactId>
        </exclusion>
      </exclusions>
    </dependency>

So we will move it to the profiles sectionas and make it only available in JIT profile :

<profile>
      <id>jit</id>
      <activation>
        <property>
          <name>!native</name>
        </property>
      </activation>
      <dependencies>
        <dependency>
          <groupId>org.fugerit.java</groupId>
          <artifactId>fj-doc-mod-fop</artifactId>
          <exclusions>
            <exclusion>
              <groupId>xml-apis</groupId>
              <artifactId>xml-apis</artifactId>
            </exclusion>
          </exclusions>
        </dependency>
      </dependencies>
    </profile>
    <profile>
      <id>native</id>
      <activation>
        <property>
          <name>native</name>
        </property>
      </activation>
      <properties>
        <skipITs>true</skipITs>
        <quarkus.native.enabled>true</quarkus.native.enabled>
      </properties>
      <dependencies>
        <dependency>
          <groupId>org.fugerit.java</groupId>
          <artifactId>fj-doc-mod-fop</artifactId>
          <scope>provided</scope>
          <exclusions>
            <exclusion>
              <groupId>xml-apis</groupId>
              <artifactId>xml-apis</artifactId>
            </exclusion>
          </exclusions>
        </dependency>
      </dependencies>
    </profile>

Of course the PDF document using Apache FOP will fail when running the native executables.

2. Update the project config file

This application use the file src/main/resources/graalkus/fm-doc-process-config.xml to load doc handlers classes by reflection, we will mark as unsafe the handlers not available in AOT mode :

<freemarker-doc-process-config>
<!-- Type handler generating xls:fo style sheet -->
<docHandler id="fo-fop" info="fo" type="org.fugerit.java.doc.mod.fop.FreeMarkerFopTypeHandlerUTF8" unsafe="true"/>
<!-- Type handler generating pdf -->
<docHandler id="pdf-fop" info="pdf" type="org.fugerit.java.doc.mod.fop.PdfFopTypeHandler" unsafe="true">
</freemarker-doc-process-config>

3. Disable relevant tests

We are going to add the JUnit 5 DisabledInNativeImage annotation to the tests that would fail :

    @Test
    @DisabledInNativeImage
    void testPdf() {
        given().when().get("/doc/example.pdf").then().statusCode(200);
    }

So now we can try again to build native image :

mvn package -Dnative

This time the build is successful and features for HTML, AsciiDoc and MarkDown documents will be available, for instance http://localhost:8080/doc/example.adoc, while the pdf version will fail http://localhost:8080/doc/example.pdf.

So we have now a project which can be built both in JIT and AOT mode.

Now it’s time for the docker images.