build-cache: ConcurrentExceptionModification

[romain-grecourt]

Version: 4.0.16

java.util.concurrent.ExecutionException: java.util.ConcurrentModificationException
    at java.util.concurrent.FutureTask.report (FutureTask.java:122)
    at java.util.concurrent.FutureTask.get (FutureTask.java:191)
    at org.apache.maven.lifecycle.internal.builder.multithreaded.MultiThreadedBuilder.multiThreadedProjectTaskSegmentBuild (MultiThreadedBuilder.java:140)
    at org.apache.maven.lifecycle.internal.builder.multithreaded.MultiThreadedBuilder.build (MultiThreadedBuilder.java:101)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:118)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:261)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:173)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:101)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:906)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:283)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:206)
    at jdk.internal.reflect.DirectMethodHandleAccessor.invoke (DirectMethodHandleAccessor.java:103)
    at java.lang.reflect.Method.invoke (Method.java:580)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:255)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:201)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:361)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:314)
Caused by: java.util.ConcurrentModificationException
    at java.util.ArrayList$ArrayListSpliterator.tryAdvance (ArrayList.java:1687)
    at java.util.stream.ReferencePipeline.forEachWithCancel (ReferencePipeline.java:129)
    at java.util.stream.AbstractPipeline.copyIntoWithCancel (AbstractPipeline.java:527)
    at java.util.stream.AbstractPipeline.copyInto (AbstractPipeline.java:513)
    at java.util.stream.AbstractPipeline.wrapAndCopyInto (AbstractPipeline.java:499)
    at java.util.stream.MatchOps$MatchOp.evaluateSequential (MatchOps.java:230)
    at java.util.stream.MatchOps$MatchOp.evaluateSequential (MatchOps.java:196)
    at java.util.stream.AbstractPipeline.evaluate (AbstractPipeline.java:234)
    at java.util.stream.ReferencePipeline.noneMatch (ReferencePipeline.java:642)
    at io.helidon.build.maven.cache.ProjectState.lambda$merge$14 (ProjectState.java:471)
    at java.util.stream.ReferencePipeline$2$1.accept (ReferencePipeline.java:178)
    at java.util.ArrayList$ArrayListSpliterator.forEachRemaining (ArrayList.java:1708)
    at java.util.stream.AbstractPipeline.copyInto (AbstractPipeline.java:509)
    at java.util.stream.AbstractPipeline.wrapAndCopyInto (AbstractPipeline.java:499)
    at java.util.stream.StreamSpliterators$WrappingSpliterator.forEachRemaining (StreamSpliterators.java:310)
    at java.util.stream.Streams$ConcatSpliterator.forEachRemaining (Streams.java:734)
    at java.util.stream.AbstractPipeline.copyInto (AbstractPipeline.java:509)
    at java.util.stream.AbstractPipeline.wrapAndCopyInto (AbstractPipeline.java:499)
    at java.util.stream.ReduceOps$ReduceOp.evaluateSequential (ReduceOps.java:921)
    at java.util.stream.AbstractPipeline.evaluate (AbstractPipeline.java:234)
    at java.util.stream.ReferencePipeline.collect (ReferencePipeline.java:682)
    at io.helidon.build.maven.cache.ProjectState.merge (ProjectState.java:472)
    at io.helidon.build.maven.cache.ProjectStateManager.save (ProjectStateManager.java:130)
    at io.helidon.build.maven.cache.LifecycleManager$ExecutionListenerImpl.projectSucceeded (LifecycleManager.java:158)
    at org.apache.maven.lifecycle.internal.DefaultExecutionEventCatapult.fire (DefaultExecutionEventCatapult.java:67)
    at org.apache.maven.lifecycle.internal.DefaultExecutionEventCatapult.fire (DefaultExecutionEventCatapult.java:38)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:114)
    at org.apache.maven.lifecycle.internal.builder.multithreaded.MultiThreadedBuilder$1.call (MultiThreadedBuilder.java:193)
    at org.apache.maven.lifecycle.internal.builder.multithreaded.MultiThreadedBuilder$1.call (MultiThreadedBuilder.java:180)
    at java.util.concurrent.FutureTask.run (FutureTask.java:317)
    at java.util.concurrent.Executors$RunnableAdapter.call (Executors.java:572)
    at java.util.concurrent.FutureTask.run (FutureTask.java:317)
    at java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1144)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:642)
    at java.lang.Thread.run (Thread.java:1583)

[tomas-langer]

Encountered the same (probably) in a pipeline during spotbugs processing (spotbugs/others):

Error: [ERROR] ConcurrentModificationException
java.util.ConcurrentModificationException
    at java.util.ArrayList$ArrayListSpliterator.forEachRemaining (ArrayList.java:1714)
    at java.util.stream.Streams$ConcatSpliterator.forEachRemaining (Streams.java:735)
    at java.util.stream.AbstractPipeline.copyInto (AbstractPipeline.java:509)
    at java.util.stream.AbstractPipeline.wrapAndCopyInto (AbstractPipeline.java:499)
    at java.util.stream.ReduceOps$ReduceOp.evaluateSequential (ReduceOps.java:921)
    at java.util.stream.AbstractPipeline.evaluate (AbstractPipeline.java:234)
    at java.util.stream.ReferencePipeline.collect (ReferencePipeline.java:682)
    at io.helidon.build.maven.cache.ProjectState.merge (ProjectState.java:472)
    at io.helidon.build.maven.cache.ProjectStateManager.save (ProjectStateManager.java:130)
    at io.helidon.build.maven.cache.LifecycleManager$ExecutionListenerImpl.projectSucceeded (LifecycleManager.java:158)
    at org.apache.maven.lifecycle.internal.DefaultExecutionEventCatapult.fire (DefaultExecutionEventCatapult.java:67)
    at org.apache.maven.lifecycle.internal.DefaultExecutionEventCatapult.fire (DefaultExecutionEventCatapult.java:38)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:114)
    at org.apache.maven.lifecycle.internal.builder.multithreaded.MultiThreadedBuilder$1.call (MultiThreadedBuilder.java:193)
    at org.apache.maven.lifecycle.internal.builder.multithreaded.MultiThreadedBuilder$1.call (MultiThreadedBuilder.java:180)
    at java.util.concurrent.FutureTask.run (FutureTask.java:317)
    at java.util.concurrent.Executors$RunnableAdapter.call (Executors.java:572)
    at java.util.concurrent.FutureTask.run (FutureTask.java:317)
    at java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1144)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:642)
    at java.lang.Thread.run (Thread.java:1583)

[romain-grecourt]

This is caused by an issue in Maven 3.9.10 where the modules are executed multiple times.

The newExecution argument to ProjectState.merge comes from ProjectExecutionManager.recordedExecutions.

This code is executed after completion of a module, see this part of the stack trace:

    at io.helidon.build.maven.cache.ProjectState.merge (ProjectState.java:472)
    at io.helidon.build.maven.cache.ProjectStateManager.save (ProjectStateManager.java:130)
    at io.helidon.build.maven.cache.LifecycleManager$ExecutionListenerImpl.projectSucceeded (LifecycleManager.java:158)

Because of duplicate executions, the list of recorded executions is modified concurrently while its being saved to a file.

helidon-build-tools/maven-plugins/build-cache-maven-extension/src/main/java/io/helidon/build/maven/cache/ProjectExecutionManager.java

Line 156 in 2b05f5f

recordedExecutions.computeIfAbsent(project, p -> new ArrayList<>())

We can mitigate the issue by using a CopyOnWriteArrayList instead of an ArrayList.