Jenkins pipeline: java.io.NotSerializableException: java.util.HashMap$Node

Question

I have a very simple Jenkins pipline code - read properties from text and call httpRequest in a loop to post this set of properties to a server. However whenever httpRequest is called in the loop, jenkins throws up this exception, it is almost impossible to tell what the error is.

If I move the httpRequest outside of the loop, it works fine - but then not sure how to iterate and post all the properties.

props = readProperties text:"hello1=world1\nhello2=world2"

for (prop in props) {
    String name = prop.key
    String value = prop.value
    println "prop $name is $value"
    httpRequest  httpMode: 'POST', url: "http://myUrl", requestBody: "Name=$name&Value=$value",  contentType: 'APPLICATION_FORM'

}

The exception is:

an exception which occurred:
    in field com.cloudbees.groovy.cps.impl.BlockScopeEnv.locals
    in object com.cloudbees.groovy.cps.impl.LoopBlockScopeEnv@69ea9f29
    in field com.cloudbees.groovy.cps.impl.ProxyEnv.parent
    in object com.cloudbees.groovy.cps.impl.BlockScopeEnv@628b19b4
    in field com.cloudbees.groovy.cps.impl.ProxyEnv.parent
    in object com.cloudbees.groovy.cps.impl.BlockScopeEnv@31a17e1b
    in field com.cloudbees.groovy.cps.impl.CallEnv.caller
    in object com.cloudbees.groovy.cps.impl.FunctionCallEnv@1b791013
    in field com.cloudbees.groovy.cps.Continuable.e
    in object org.jenkinsci.plugins.workflow.cps.SandboxContinuable@4de530bb
    in field org.jenkinsci.plugins.workflow.cps.CpsThread.program
    in object org.jenkinsci.plugins.workflow.cps.CpsThread@7c155bf7
    in field org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.threads
    in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@5269cced
    in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@5269cced
Caused: java.io.NotSerializableException: java.util.HashMap$Node
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:860)
    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(ObjectOutputStream.java:344)
    at java.util.HashMap.internalWriteEntries(HashMap.java:1785)
    at java.util.HashMap.writeObject(HashMap.java:1362)
    at sun.reflect.GeneratedMethodAccessor113.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.jboss.marshalling.reflect.SerializableClass.callWriteObject(SerializableClass.java:273)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:976)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1032)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:988)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:967)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1032)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:988)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:967)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1032)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:988)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:967)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1032)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:988)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:967)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1032)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:988)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:967)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1032)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:988)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854)
    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(ObjectOutputStream.java:344)
    at java.util.TreeMap.writeObject(TreeMap.java:2438)
    at sun.reflect.GeneratedMethodAccessor132.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.jboss.marshalling.reflect.SerializableClass.callWriteObject(SerializableClass.java:273)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:976)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1032)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:988)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854)
    at org.jboss.marshalling.AbstractObjectOutput.writeObject(AbstractObjectOutput.java:58)
    at org.jboss.marshalling.AbstractMarshaller.writeObject(AbstractMarshaller.java:111)
    at org.jenkinsci.plugins.workflow.support.pickles.serialization.RiverWriter.lambda$writeObject$0(RiverWriter.java:144)
    at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.GroovySandbox.runInSandbox(GroovySandbox.java:108)
    at org.jenkinsci.plugins.workflow.support.pickles.serialization.RiverWriter.writeObject(RiverWriter.java:143)
    at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgram(CpsThreadGroup.java:467)
    at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgram(CpsThreadGroup.java:443)
    at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgramIfPossible(CpsThreadGroup.java:430)
    at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:367)
    at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$200(CpsThreadGroup.java:82)
    at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:243)
    at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:231)
    at org.jenkinsci.plugins.workflow.cps.CpsVmExecutorService$2.call(CpsVmExecutorService.java:64)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at hudson.remoting.SingleLaneExecutorService$1.run(SingleLaneExecutorService.java:112)
    at jenkins.util.ContextResettingExecutorService$1.run(ContextResettingExecutorService.java:28)
    at java.util.concurrent.Executors$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)

Answer 1

You are getting the exception not serializable exception because Jenkins will from time to time save the current state on the pipeline to disk making the assumption that every object in env is serializable.

Unfortunately, HashMap$Node is not serializable so you will have to do something else. And I suggest

def props = readProperties text:"hello1=world1\nhello2=world2"

for(def key : props.keySet()){
     def value = props.get(key)
     println "prop $key is $value"
}

Answer 2

I installed this plugin and created the following pipeline (I couldn't test the request of course without more info but the iteration is showed).

pipeline {
    agent any 

    stages {
        stage('test'){
            steps {
                script {
                    def props = readProperties text:"hello1=world1\nhello2=world2"
                    for (prop in props) {
                        String name = prop.key
                        String value = prop.value
                        println "prop $name is $value"
                        //httpRequest  httpMode: 'POST', url: "http://myUrl", requestBody: "Name=$name&Value=$value",  contentType: 'APPLICATION_FORM'
                    }
                }
            }
        }
    }  
}