I use git polling to trigger my jobs. I recognized a Exception within the "Git Polling Log":
Started on 17.03.2015 15:40:08 Using strategy: Default [poll] Last Built Revision: Revision ae505d729d3b76e43782b351d7628024e065db61 (refs/remotes/origin/master) ERROR: Failed to record SCM polling for hudson.maven.MavenModuleSet@42caa9c4[(BUILD) mp-modules master unit] java.lang.RuntimeException: Unable to determine Maven version at org.jfrog.hudson.maven3.extractor.MavenExtractorEnvironment.isMavenVersionValid(MavenExtractorEnvironment.java:151) at org.jfrog.hudson.maven3.extractor.MavenExtractorEnvironment.buildEnvVars(MavenExtractorEnvironment.java:106) at hudson.model.AbstractBuild.getEnvironment(AbstractBuild.java:914) at hudson.maven.AbstractMavenBuild.getEnvironment(AbstractMavenBuild.java:56) at hudson.maven.MavenModuleSetBuild.getEnvironment(MavenModuleSetBuild.java:167) at hudson.plugins.git.GitSCM.compareRemoteRevisionWithImpl(GitSCM.java:564) at hudson.plugins.git.GitSCM.compareRemoteRevisionWith(GitSCM.java:526) at hudson.scm.SCM.compareRemoteRevisionWith(SCM.java:380) at hudson.scm.SCM.poll(SCM.java:397) at hudson.model.AbstractProject._poll(AbstractProject.java:1446) at hudson.model.AbstractProject.poll(AbstractProject.java:1349) at jenkins.triggers.SCMTriggerItem$SCMTriggerItems$Bridge.poll(SCMTriggerItem.java:119) at hudson.triggers.SCMTrigger$Runner.runPolling(SCMTrigger.java:515) at hudson.triggers.SCMTrigger$Runner.run(SCMTrigger.java:544) at hudson.util.SequentialExecutionQueue$QueueEntry.run(SequentialExecutionQueue.java:118) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745) Caused by: java.lang.NullPointerException at org.jfrog.hudson.util.MavenVersionHelper.getMavenInstallation(MavenVersionHelper.java:105) at org.jfrog.hudson.util.MavenVersionHelper.isAtLeastVersion(MavenVersionHelper.java:81) at org.jfrog.hudson.util.MavenVersionHelper.isAtLeastResolutionCapableVersion(MavenVersionHelper.java:72) at org.jfrog.hudson.maven3.extractor.MavenExtractorEnvironment.isMavenVersionValid(MavenExtractorEnvironment.java:149) ... 19 more
The exception occurs when the the git polling is triggered while the job is already in progress. The changes will not be polled again. If there is another change after the job has finished also the changes in the aborted poll will be build.