Moving Hibernate instrumentation to build time

Question

I have an application with about 3000 entities (I know it's a lot but I can't change it). When the application loads it takes Hibernate a minutes to do all the instrumentation and the SessionFactory setup stuff.
I was wondering if I can configure Hibernate to do the instrumentation on the original classes during build time.
This way I can avoid 3000 additional generated proxy classes and the huge overhead on application start-up.
I've found some information on Hibernate build time instrumentation (org.hibernate.tool.instrument.javassist.InstrumentTask) but it isn't clear whether this replaces totally the run-time instrumentation or only handles the Hibernate lazy property fetching mechanism.
Any information on how to move the proxy generation to build time will be appreciated.

Answer 1

Yes, you can. There is an Ant task in the Hibernate code : org.hibernate.tool.instrument.javassist.InstrumentTask.

<target name="instrument" depends="compile">
    <taskdef name="instrument" classname="org.hibernate.tool.instrument.javassist.InstrumentTask">
        <classpath refid="<some-ant-path-including-hibernate-core-jar>"/>
        <classpath path="<your-classes-path>"/>
    </taskdef>

    <instrument verbose="true">
        <fileset dir="<your-classes>">
            <include name="*.class"/>
        </fileset>
    </instrument>
</target>

I have seen some Maven based ones as well.

Answer 2

Since Hibernate 4.2.8 you can use the hibernate-enhance-maven-plugin:

<build>
    <plugins>
        <plugin>
            <groupId>org.hibernate.orm.tooling</groupId>
            <artifactId>hibernate-enhance-maven-plugin</artifactId>
            <executions>
                <execution>
                    <phase>process-test-resources</phase>
                    <goals>
                        <goal>enhance</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Answer 3

Found the solution on the internet. Tried it rapidly, and it seems to work. Hope I am not to late..

The idea is to use maven-antrun-plugin. You need to had this in your pom.xml in the build/plugins section.

In the exemple bellow, don't forget: - to replace the ${hibernate.version} and ${javassist.version} with the version you are using. - to modify the include rules to have InstrumentTask runs only on your entity

<plugin>
            <artifactId>maven-antrun-plugin</artifactId>
            <executions>
                <execution>
                    <id>Instrument domain classes</id>
                    <configuration>
                        <tasks>
                            <taskdef name="instrument"
                                     classname="org.hibernate.tool.instrument.javassist.InstrumentTask">
                                <classpath>
                                    <path refid="maven.dependency.classpath"/>
                                    <path refid="maven.plugin.classpath"/>
                                </classpath>
                            </taskdef>
                            <instrument verbose="true">
                                <fileset dir="${project.build.outputDirectory}">
                                    <include name="**/model/**/*.class"/>
                                </fileset>
                            </instrument>
                        </tasks>
                    </configuration>
                    <phase>process-classes</phase>
                    <goals>
                        <goal>run</goal>
                    </goals>
                </execution>
            </executions>
            <dependencies>
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-core</artifactId>
                    <version>${hibernate.version}</version>
                </dependency>

                <dependency>
                    <groupId>javassist</groupId>
                    <artifactId>javassist</artifactId>
                    <version>${javassist.version}</version>
                </dependency>
            </dependencies>
        </plugin>