parallel test execution throws ConcurrentModificationException

[vmj]

Task List

• [x] Steps to reproduce provided
• [x] Stacktrace (if present) provided
• [ ] Example that reproduces the problem uploaded to Github
• [x] Full description of the issue provided (see below)

Steps to Reproduce

1. Generate a minimal application: mn create-app -b=gradle --jdk=11 -l=java -t=spock demo
2. Change into demo: cd demo
3. Overwrite the spock version in build.gradle: testImplementation("org.spockframework:spock-core:2.0-M4-groovy-3.0")
4. Make test resources directory: mkdir -p src/test/resources
5. Enable parallel test execution by adding file src/test/resources/SpockConfig.groovy:

   runner {
       parallel {
           enabled true
       }
   }
   

6. Make the example test run a few times, e.g. by adding a where block:

   @MicronautTest
   class DemoSpec extends Specification {
   
       @Inject
       EmbeddedApplication<?> application
   
       void 'test it works'() {
           expect:
           application.running
   
           where:
           id << (0..100).asList()
       }
   }
   

7. Run the tests: ./gradlew --no-build-cache clean test

Expected Behaviour

Tests should pass. I.e. BUILD SUCCESSFUL.

Actual Behaviour

About 3 out of 5 times some of the tests fail with the following error:

java.util.ConcurrentModificationException
	at java.base/java.util.HashMap.compute(HashMap.java:1229)
	at io.micronaut.test.extensions.AbstractMicronautExtension.beforeEach(AbstractMicronautExtension.java:253)
	at io.micronaut.test.extensions.spock.MicronautSpockExtension.lambda$visitSpecAnnotation$5(MicronautSpockExtension.java:133)
	at org.spockframework.runtime.extension.MethodInvocation.proceed(MethodInvocation.java:101)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:136)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
	at org.spockframework.runtime.model.MethodInfo.invoke(MethodInfo.java:136)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
	at org.junit.platform.engine.support.hierarchical.ForkJoinPoolHierarchicalTestExecutorService$ExclusiveTask.compute(ForkJoinPoolHierarchicalTestExecutorService.java:185)
	at java.base/java.util.concurrent.RecursiveAction.exec(RecursiveAction.java:189)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)

Seems to refer to testProperties field in AbstractMicronautExtension class.

Environment Information

• Operating System: macOS 10.15.7
• Micronaut Version: 2.1.2
• JDK Version:

  openjdk version "11.0.9" 2020-10-20 LTS
  OpenJDK Runtime Environment Zulu11.43+21-CA (build 11.0.9+11-LTS)
  OpenJDK 64-Bit Server VM Zulu11.43+21-CA (build 11.0.9+11-LTS, mixed mode)
  

[alvarosanchez]

I guess this maps could be changed to ConcurrentHashMaps.

[graemerocher]

I'm not sure these extensions are designed to be concurrently executed, and not sure I understand why Gradle's parallel test support is allowing parallel access to extensions

[vmj]

I'm not sure these extensions are designed to be concurrently executed, and not sure I understand why Gradle's parallel test support is allowing parallel access to extensions

You probably meant Spock's parallel execution. It's a new feature in Spock 2.0 M4.

Yes, there's a larger question of how spock extensions should be implemented to support it.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ecmel]

JUnit parallel test execution also fails.

[supriya-tw]

Is there any plan to support this?