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  1. Jenkins
  2. JENKINS-17125

FingerprintAction deserialization leads to NPE


      FingerprintAction has the following field:

      private final AbstractBuild build;

      This field links to an AbstractBuild, which in turn has the following field:

      protected transient final JobT project;

      Once Jenkin persists a run to a file, the build from the FingerprintAction will be saved, but the project itself will not get saved. An example fragment from one of the build files looks like this:

            <build class="build">
                <hudson.model.ParametersAction reference="../../../../hudson.model.ParametersAction"/>
                <hudson.model.CauseAction reference="../../../../hudson.model.CauseAction"/>
                <hudson.plugins.copyartifact.CopyArtifact_-EnvAction reference="../../../../hudson.plugins.copyartifact.CopyArtifact_-EnvAction"/>
                <hudson.tasks.Fingerprinter_-FingerprintAction reference="../../.."/>
              <scm class="hudson.scm.NullChangeLogParser"/>
              <culprits class="com.google.common.collect.EmptyImmutableSortedSet"/>

      When the files are read and the objects are created, the project field remains empty. During intialization, the onLoad() method is called:

          protected R retrieve(File d) throws IOException {
              if(new File(d,"build.xml").exists()) {
                  // if the build result file isn't in the directory, ignore it.
                  try {
                      R b = cons.create(d);
                      if (LOGGER.isLoggable(FINE))
                          LOGGER.log(FINE,"Loaded " + b.getFullDisplayName(),new ThisIsHowItsLoaded());
                      return b;
                  } catch (IOException e) {
                      LOGGER.log(Level.WARNING, "could not load " + d, e);
                  } catch (InstantiationError e) {
                      LOGGER.log(Level.WARNING, "could not load " + d, e);
              return null;

      This method invokes onLoad() on all actions that implement RunAction:

              for (Action a : getActions())
                  if (a instanceof RunAction)
                      ((RunAction) a).onLoad();

      The FingerprintAction does implement the RunAction interface, and the method is implemented as follows:

              public void onLoad() {
                  // share data structure with nearby builds, but to keep lazy loading efficient,
                  // don't go back the history forever.
                  if (rand.nextInt(2)!=0) {
                      Run pb = build.getPreviousBuild();
                      if (pb!=null) {
                          FingerprintAction a = pb.getAction(FingerprintAction.class);
                          if (a!=null)

      Build is set, so getPreviousBuild() can be called, this will however fail because the project is null (due to the transient field) and will throw a NullPointerException.

      This causes very strange behavior as sometimes pages are working, sometimes they are not. There are a lot of stack traces around that actually look like as if they were caused by the same problem, for example: https://issues.jenkins-ci.org/browse/JENKINS-16845

      Stack Trace looks like this:

      Caused by: java.lang.NullPointerException
      	at hudson.model.AbstractBuild.getPreviousBuild(AbstractBuild.java:207)
      	at hudson.tasks.Fingerprinter$FingerprintAction.onLoad(Fingerprinter.java:349)
      	at hudson.model.Run.onLoad(Run.java:315)
      	at hudson.model.RunMap.retrieve(RunMap.java:221)
      	at hudson.model.RunMap.retrieve(RunMap.java:59)
      	at jenkins.model.lazy.AbstractLazyLoadRunMap.load(AbstractLazyLoadRunMap.java:638)
      	at jenkins.model.lazy.AbstractLazyLoadRunMap.load(AbstractLazyLoadRunMap.java:601)
      	at jenkins.model.lazy.AbstractLazyLoadRunMap.search(AbstractLazyLoadRunMap.java:344)
      	at hudson.model.AbstractBuild.getPreviousBuild(AbstractBuild.java:207)
      	at hudson.model.AbstractBuild.getPreviousBuild(AbstractBuild.java:100)
      	at hudson.model.RunMap$1.next(RunMap.java:107)
      	at hudson.model.RunMap$1.next(RunMap.java:96)
      	at hudson.widgets.HistoryWidget.getRenderList(HistoryWidget.java:133)
      	... 122 more

            jglick Jesse Glick
            homes2001 Dominik Bieringer
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