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

Question

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$3.run(LightArrayRevolverScheduler.scala:235)
at java.lang.Thread.run(Thread.java:748)
I have tried to increase heap space to 10 GB (-Xmx10g) in different ways:
via environment property MAVEN_OPTS=-Xmx10g
via local project maven options .mvn/jvm.config
via maven-surefire-plugin configuration as suggested here
Although 10GB is allocated for maven process as you can see at the start of maven process:
VM settings:
Min. Heap Size: 1.00G
Max. Heap Size: 10.00G
Ergonomics Machine Class: client
Using VM: Java HotSpot(TM) 64-Bit Server VM
but the OutOfMemoryError is still thrown during each gatling-plugin execution.
When analyzing each heap dump eclipse memory analyzer indicates always the same results:
84 instances of "com.intuit.karate.core.StepResult", loaded by "sun.misc.Launcher$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?

Answer 1

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>

Answer 2

You can try this
<configuration>
<meminitial>1024m</meminitial>
<maxmem>4096m</maxmem>
</configuration>