JVM args issue with gatling maven plugin

[Sandeep Malik]

Hi All,

I was trying to put some custom jvm arguments e.g.

<plugin>

                    <groupId>io.gatling</groupId>

                    <artifactId>gatling-maven-plugin</artifactId>

                    <version>2.0.0-M3a</version>

                    <executions>

                        <execution>

                            <phase>test</phase>

                            <goals>

                                <goal>execute</goal>

                            </goals>

                        </execution>

                    </executions>

                    <configuration>

                        ...

                        <simulationClass>itemstore.simulations.StandaloneProductSimulation</simulationClass>

                        <jvmArgs>

                            <jvmArg>-Xms1024m</jvmArg>

                            <jvmArg>-Xmx4096m</jvmArg>

                        </jvmArgs>

                    ...

but looks like no matter what memory sizes I give here, the simulation code always runs with 512M of min and max memory.

After digging a little deeper (I am using 2.0.0-M3a version of plugin), I found that 512M is default min and max values for heap size. 

I looked at the GatlingMojo.java class and the method which builds jvm args is this:

private List<String> jvmArgs() {

List<String> jvmArguments = (jvmArgs != null) ? jvmArgs : new ArrayList<String>();

jvmArguments.addAll(Arrays.asList(JVM_ARGS));

return jvmArguments;

}

Now, since we're adding default properties in an array list to the existing jvmArgs, the -Xms and _Xmx will be added twice. The final list would look something like "... -Xms1024M ... -Xms512M ..."

In this scenario, looks like JVM is picking up the rightmost arg value and hence ignoring my custom options. 

Is this a bug? 

May be the code should have been:

private List<String> jvmArgs() {

List<String> jvmArguments = (jvmArgs != null) ? jvmArgs : new ArrayList<String>();

Arrays.asList(JVM_ARGS).addAll(jvmArguments) // reverse order:

return jvmArguments;

}

Or may be we could have used a Set (in the same order, custom first, defaults later) to make sure that properties are not overridden by default.

Thanks,

Sandeep

[Stéphane Landelle]

Hi,

This has already been fixed in master: https://github.com/excilys/gatling-maven-plugin/blob/master/src/main/java/io/gatling/mojo/GatlingMojo.java#L257

FYI, how JVM are picked is not specified, you cannot rely on this.

Cheers,

Stéphane

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[Sandeep Malik]

Thanks Stephane! Appreciate quick help, and you're right about JVM agrs order.

Thanks,

Sandeep

[Stéphane Landelle]

You're welcome!

If you plan on using the plugin snapshot, beware, it's only compatible with Gatling modules snapshots.