karate-gatling: how to resolve java heap space OutOfMemoryError?

Currently I'm trying to run our functional tests (about 300 requests) with 10 users in parallel using gatling-plugin

mvn clean test-compile gatling:test -Dkarate.env=test

with the following .mvn/jvm.config local maven options in the project folder:

-d64 -Xmx4g -Xms1g -XshowSettings:vm -Djava.awt.headless=true

At some point while processing some big response in parallel the gatling process is aborted:

[ERROR] Failed to execute goal io.gatling:gatling-maven-plugin:3.0.2:test (default-cli) on project np.rest-testing: Gatling failed.: Process exited with an error: -1 (Exit value: -1) -> [Help 1]

with the following stack trace:

java.lang.OutOfMemoryError: Java heap space
Dumping heap to java_pid25960.hprof ...
Heap dump file created [1611661680 bytes in 18.184 secs]
Uncaught error from thread [GatlingSystem-scheduler-1]: Java heap space, shutting down JVM since 'akka.jvm-exit-on-fatal-error' is enabled for ActorSystem[GatlingSystem]
java.lang.OutOfMemoryError: Java heap space
        at akka.actor.LightArrayRevolverScheduler$$anon$3.nextTick(LightArrayRevolverScheduler.scala:269)
        at akka.actor.LightArrayRevolverScheduler$$anon$3.run(LightArrayRevolverScheduler.scala:235)
        at java.lang.Thread.run(Thread.java:748)

I have tried to increase heap space to 10 GB (-Xmx10g) in different ways:

1. via environment property MAVEN_OPTS=-Xmx10g
2. via local project maven options .mvn/jvm.config
3. via maven-surefire-plugin configuration as suggested here

Although 10GB is allocated for maven process as you can see at the start of maven process:

VM settings:
    Min. Heap Size: 1.00G
    Max. Heap Size: 10.00G
    Ergonomics Machine Class: client
    Using VM: Java HotSpot(TM) 64-Bit Server VM

but the OutOfMemoryError is still thrown during each gatling-plugin execution.

When analyzing each heap dump eclipse memory analyzer indicates always the same results:

84 instances of "com.intuit.karate.core.StepResult", loaded by "sun.misc.Launcher$AppClassLoader @ 0xc0000000" occupy 954 286 864 (90,44 %) bytes. 

Biggest instances:
•com.intuit.karate.core.StepResult @ 0xfb93ced8 - 87 239 976 (8,27 %) bytes... 

What can be done to reduce the heap space usage and prevent OutOfMemoryError? Can someone share some thoughts and experience?

After some investigations I've finally noticed, that heap dump shows always 1GB. That means the increased heap space is not used by gatling-plugin.

By adding the following jvm argument to the plugin, the problem is solved even with 4GB:

<jvmArgs>
    <jvmArg>-Xmx4g</jvmArg>
</jvmArgs>

So, with the following gatling-plugin configuration the error doesn't appear any more:

         <plugin>
            <groupId>io.gatling</groupId>
            <artifactId>gatling-maven-plugin</artifactId>
            <version>${gatling.plugin.version}</version>
            <configuration>
                <simulationsFolder>src/test/java</simulationsFolder>
                <includes>
                    <include>performance.test.workflow.WorkflowSimulation</include>
                </includes>
                <compilerJvmArgs>
                    <compilerJvmArg>-Xmx512m</compilerJvmArg>
                </compilerJvmArgs>
                <jvmArgs>
                    <jvmArg>-Xmx4g</jvmArg>
                </jvmArgs>
            </configuration>
        </plugin>