Jenkins Pipeline NotSerializableException: groovy.json.internal.LazyMap

Solved: Thanks to below answer from S.Richmond. I needed to unset all stored maps of the groovy.json.internal.LazyMap type which meant nullifying the variables envServers and object after use.

Additional: People searching for this error might be interested to use the Jenkins pipeline step readJSON instead - find more info here.

I am trying to use Jenkins Pipeline to take input from the user which is passed to the job as json string. Pipeline then parses this using the slurper and I pick out the important information. It will then use that information to run 1 job multiple times in parallel with differeing job parameters.

Up until I add the code below "## Error when below here is added" the script will run fine. Even the code below that point will run on its own. But when combined I get the below error.

I should note that the triggered job is called and does run succesfully but the below error occurs and fails the main job. Because of this the main job does not wait for the return of the triggered job. I could try/catch around the build job: however I want the main job to wait for the triggered job to finish.

Can anyone assist here? If you need anymore information let me know.

Cheers

def slurpJSON() {
return new groovy.json.JsonSlurper().parseText(BUILD_CHOICES);
}

node {
  stage 'Prepare';
  echo 'Loading choices as build properties';
  def object = slurpJSON();

  def serverChoices = [];
  def serverChoicesStr = '';

  for (env in object) {
     envName = env.name;
     envServers = env.servers;

     for (server in envServers) {
        if (server.Select) {
            serverChoicesStr += server.Server;
            serverChoicesStr += ',';
        }
     }
  }
  serverChoicesStr = serverChoicesStr[0..-2];

  println("Server choices: " + serverChoicesStr);

  ## Error when below here is added

  stage 'Jobs'
  build job: 'Dummy Start App', parameters: [[$class: 'StringParameterValue', name: 'SERVER_NAME', value: 'TestServer'], [$class: 'StringParameterValue', name: 'SERVER_DOMAIN', value: 'domain.uk'], [$class: 'StringParameterValue', name: 'APP', value: 'application1']]

}

Error:

java.io.NotSerializableException: groovy.json.internal.LazyMap
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:860)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:569)
    at org.jboss.marshalling.river.BlockMarshaller.doWriteObject(BlockMarshaller.java:65)
    at org.jboss.marshalling.river.BlockMarshaller.writeObject(BlockMarshaller.java:56)
    at org.jboss.marshalling.MarshallerObjectOutputStream.writeObjectOverride(MarshallerObjectOutputStream.java:50)
    at org.jboss.marshalling.river.RiverObjectOutputStream.writeObjectOverride(RiverObjectOutputStream.java:179)
    at java.io.ObjectOutputStream.writeObject(Unknown Source)
    at java.util.LinkedHashMap.internalWriteEntries(Unknown Source)
    at java.util.HashMap.writeObject(Unknown Source)
...
...
Caused by: an exception which occurred:
    in field delegate
    in field closures
    in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@5288c

Solution

I ran into this myself today and through some bruteforce I've figured out both how to resolve it and potentially why.

Probably best to start with the why:

Jenkins has a paradigm where all jobs can be interrupted, paused, and resumable through server reboots. To achieve this the pipeline and its data must be fully serializable - IE it needs to be able to save the state of everything. Similarly, it needs to be able to serialize the state of global variables between nodes and sub-jobs in the build, which is what I think is happening for you and me and why it only occurs if you add that additional build step.

For whatever reason JSONObject isn't serializable by default. I'm not a Java dev so I cannot say much more on the topic sadly. There are plenty of answers out there about how one may fix this properly though I do not know how applicable they are to Groovy and Jenkins. See this post for a little more info.

How you fix it:

If you know how you can make the JSONObject serializable somehow. Otherwise, you can resolve it by ensuring no global variables are of that type.

Try unsetting your object var or wrapping it in a method so its scope isn't node global.