[MCHECKSTYLE-230] ConcurrentModificationException in FileResourceLoader.getResource

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 2.12.1
• Assignee: Herve Boutemy
• Reporter: Andrew Gaul
• Created: 20/May/14 22:09
• Updated: 06/Jan/16 20:46
• Resolved: 18/Aug/14 07:53

Description

I encountered a ConcurrentModificationException when running:

mvn checkstyle:checkstyle -e -T 4

against the jclouds code base:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-checkstyle-plugin:2.12.1:checkstyle (default-cli) on project ultradns-ws: Execution default-cli of goal org.apache.maven.plugins:maven-checkstyle-plugin:2.12.1:checkstyle failed. ConcurrentModificationException -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-checkstyle-plugin:2.12.1:checkstyle (default-cli) on project ultradns-ws: Execution default-cli of goal org.apache.maven.plugins:maven-checkstyle-plugin:2.12.1:checkstyle failed.
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:224)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
        at org.apache.maven.lifecycle.internal.LifecycleThreadedBuilder$1.call(LifecycleThreadedBuilder.java:169)
        at org.apache.maven.lifecycle.internal.LifecycleThreadedBuilder$1.call(LifecycleThreadedBuilder.java:165)
        at java.util.concurrent.FutureTask.run(FutureTask.java:262)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
        at java.util.concurrent.FutureTask.run(FutureTask.java:262)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) 
        at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default-cli of goal org.apache.maven.plugins:maven-checkstyle-plugin:2.12.1:checkstyle failed.  
        at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:115)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:208)
        ... 11 more
Caused by: java.util.ConcurrentModificationException
        at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:859)
        at java.util.ArrayList$Itr.next(ArrayList.java:831)
        at org.codehaus.plexus.resource.loader.FileResourceLoader.getResource(FileResourceLoader.java:56)
        at org.apache.maven.plugin.checkstyle.resource.LicenseResourceManager.getResource(LicenseResourceManager.java:70)
        at org.codehaus.plexus.resource.DefaultResourceManager.getResourceAsFile(DefaultResourceManager.java:91)
        at org.apache.maven.plugin.checkstyle.DefaultCheckstyleExecutor.getOverridingProperties(DefaultCheckstyleExecutor.java:460)
        at org.apache.maven.plugin.checkstyle.DefaultCheckstyleExecutor.getConfiguration(DefaultCheckstyleExecutor.java:299)
        at org.apache.maven.plugin.checkstyle.DefaultCheckstyleExecutor.executeCheckstyle(DefaultCheckstyleExecutor.java:185)
        at org.apache.maven.plugin.checkstyle.AbstractCheckstyleReport.executeReport(AbstractCheckstyleReport.java:488)
        at org.apache.maven.plugin.checkstyle.CheckstyleReport.executeReport(CheckstyleReport.java:156)
        at org.apache.maven.reporting.AbstractMavenReport.generate(AbstractMavenReport.java:196)
        at org.apache.maven.reporting.AbstractMavenReport.execute(AbstractMavenReport.java:104)
        at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:106)
        ... 12 more

The underlying problem appears to be within plexus resources and I have opened an issue and submitted a possible fix:

http://jira.codehaus.org/browse/PLXCOMP-237

Issue Links

• is related to: MCHECKSTYLE-138 Checkstyle plugin is @threadSafe if checkstyle itself is threadsafe
• relates to: MCHECKSTYLE-238 ConcurrentModificationException
• relates to: MCHECKSTYLE-244 LicenseResourceManager component is not thread safe and causes parallel build failures