[JENKINS-27421] Unserializable iterator & entry classes from Java Collections

[jenkins-infra-bot]

Not currently possible to use a Java 5-style for loop on an ArrayList (for example) from within CPS-transformed code, since its Iterator implementation is not marked Serializable.

---

Originally reported by jglick, imported from: Unserializable iterator & entry classes from Java Collections

• assignee: jglick
• status: Resolved
• priority: Major
• component(s): workflow-cps-plugin
• label(s): groovy, serialization
• resolution: Fixed
• resolved: 2017-08-21T14:55:09+00:00
• votes: 38
• watchers: 59
• imported: 2025-12-07

Raw content of original issue

Not currently possible to use a Java 5-style for loop on an ArrayList (for example) from within CPS-transformed code, since its Iterator implementation is not marked Serializable.

[jenkins-infra-bot]

• Remote links associated with this issue:

  • PR 206
  • PR 372
  • PR 9
  • workflow-cps PR 77
  • workflow-cps PR 124

[jenkins-infra-bot]

sumdumgai:

• Original comment link
• Raw content of original comment:

  bump The inability to use collection iterators at all is a very significant limitation.
  

bump The inability to use collection iterators at all is a very significant limitation.

[jenkins-infra-bot]

jglick:

• Original comment link
• Raw content of original comment:

  Workarounds:
  
  · Use a plain C-style for-loop.
  · Wrap the code in a method marked @NonCps, assuming it does not invoke anything interruptible (incl. calling Workflow steps).
  

Workarounds:

· Use a plain C-style for-loop.
· Wrap the code in a method marked @​NonCps, assuming it does not invoke anything interruptible (incl. calling Workflow steps).

[jenkins-infra-bot]

owenmehegan:

• Original comment link
• Raw content of original comment:

  Being able to write:
  
  node('linux_slave', 'windows_slave') {
    // some steps to run in parallel on both slaves
  }
  
  would be fantastic.
  

Being able to write:

node('linux_slave', 'windows_slave') {
// some steps to run in parallel on both slaves
}

would be fantastic.

[jenkins-infra-bot]

jglick:

• Original comment link
• Raw content of original comment:

  owenmehegan you can already do that using
  
  
  def labels = ['linux', 'windows']
  for (int i = 0; i < labels.size(); i++) {
    node(labels.get(i)) {
      // something, though you presumably need to select sh vs. bat here
    }
  }
  
  
  

owenmehegan you can already do that using

def labels = ['linux', 'windows']
for (int i = 0; i < labels.size(); i++) {
  node(labels.get(i)) {
    // something, though you presumably need to select sh vs. bat here
  }
}

[jenkins-infra-bot]

scm_issue_link:

• Original comment link
• Raw content of original comment:

  Code changed in jenkins
  User: Jesse Glick
  Path:
   aggregator/src/test/java/org/jenkinsci/plugins/workflow/SerializationTest.java
  http://jenkins-ci.org/commit/workflow-plugin/e916b5e9f35b00db679360dc29e42658d566efb7
  Log:
    JENKINS-27421 Reproduced in test.
  
  
  

Code changed in jenkins
User: Jesse Glick
Path:
aggregator/src/test/java/org/jenkinsci/plugins/workflow/SerializationTest.java
http://jenkins-ci.org/commit/workflow-plugin/e916b5e9f35b00db679360dc29e42658d566efb7
Log:
JENKINS-27421 Reproduced in test.

[jenkins-infra-bot]

scm_issue_link:

• Original comment link
• Raw content of original comment:

  Code changed in jenkins
  User: Jesse Glick
  Path:
   aggregator/src/test/java/org/jenkinsci/plugins/workflow/PersistenceFailureTest.java
   aggregator/src/test/java/org/jenkinsci/plugins/workflow/PersistenceProblemStep.java
   aggregator/src/test/java/org/jenkinsci/plugins/workflow/PersistenceProblemStepExecution.java
   aggregator/src/test/java/org/jenkinsci/plugins/workflow/SerializationTest.java
   aggregator/src/test/java/org/jenkinsci/plugins/workflow/WorkflowTest.java
  http://jenkins-ci.org/commit/workflow-plugin/61b7d70b1238d9d66dea22f497cac26debaaf88e
  Log:
    Merge pull request #206 from jglick/Itr-JENKINS-27421
  
  JENKINS-27421 Investigating ArrayList.Itr problem
  
  
  Compare: jenkinsci/pipeline-plugin@a24f130...61b7d70
  
  

Code changed in jenkins
User: Jesse Glick
Path:
aggregator/src/test/java/org/jenkinsci/plugins/workflow/PersistenceFailureTest.java
aggregator/src/test/java/org/jenkinsci/plugins/workflow/PersistenceProblemStep.java
aggregator/src/test/java/org/jenkinsci/plugins/workflow/PersistenceProblemStepExecution.java
aggregator/src/test/java/org/jenkinsci/plugins/workflow/SerializationTest.java
aggregator/src/test/java/org/jenkinsci/plugins/workflow/WorkflowTest.java
http://jenkins-ci.org/commit/workflow-plugin/61b7d70b1238d9d66dea22f497cac26debaaf88e
Log:
Merge pull request #206 from jglick/Itr-JENKINS-27421

JENKINS-27421 Investigating ArrayList.Itr problem

Compare: jenkinsci/pipeline-plugin@a24f130...61b7d70

[jenkins-infra-bot]

ssides:

• Original comment link
• Raw content of original comment:

  Here's another context where moving away from foreach was not effective. 
  I was reading some mercurial repositories with source and subdir (to check out to) from a json file:
  
  
  for(repomap in jsonrepos.configs.repos) {
      for ( key in repomap.keySet() ){
          source = repomap.get(key)['source']
          subdir = repomap.get(key)['subdir']
          checkout([$class: 'MercurialSCM', credentialsId: '', installation: '(Default)', source: "${source}", subdir: "${subdir}"])
     }
  
  
  This looked nice and elegant, but I hit this exception noted in this bug, so I removed the foreach loops (I include the json steps here):
  
  def slurper = new JsonSlurper()
  def jsonText = readFile 'flow-configs/prebuild.json'
  jsonrepos = slurper.parseText( jsonText )
  repoCount = jsonrepos.configs.repos.size
  println "repositories: ${repoCount}"
  for ( i = 0 ; i < repoCount ; i++ ) {
      rmap = jsonrepos.configs.repos[i]
      key = rmap.keySet().toList().getAt(0)
      source = rmap.get(key)['source']
      subdir = rmap.get(key)['subdir']
      println("  source: ${source}  subdir: ${subdir}")
      checkout([$class: 'MercurialSCM', credentialsId: '', installation: '(Default)', source: "${source}", subdir: "${subdir}"])
  }
  
  
  It's fine up to the println statement. If you comment out the checkout line, it's all good and prints all the repsitories and subdir info, but if I uncomment out the checkout line I get this exception, which is similar to the rest reported except for the slurper part (which is curious).
  This may be a different bug(???), but the stack trace seems to be the same (except the json.JsonSlurper) as other bugs referred to as another instance of this bug.
  java.io.NotSerializableException: groovy.json.JsonSlurper
  	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:1777)
  	at java.util.HashMap.writeObject(HashMap.java:1354)
  	at sun.reflect.GeneratedMethodAccessor199.invoke(Unknown Source)
  	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  	at java.lang.reflect.Method.invoke(Method.java:497)
  	at org.jboss.marshalling.reflect.SerializableClass.callWriteObject(SerializableClass.java:271)
  	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.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.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:2434)
  	at sun.reflect.GeneratedMethodAccessor206.invoke(Unknown Source)
  	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  	at java.lang.reflect.Method.invoke(Method.java:497)
  	at org.jboss.marshalling.reflect.SerializableClass.callWriteObject(SerializableClass.java:271)
  	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.writeObject(RiverWriter.java:132)
  	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgram(CpsThreadGroup.java:344)
  	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgram(CpsThreadGroup.java:328)
  	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:303)
  	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$000(CpsThreadGroup.java:71)
  	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:180)
  	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:178)
  	at org.jenkinsci.plugins.workflow.cps.CpsVmExecutorService$2.call(CpsVmExecutorService.java:47)
  	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)
  Caused by: an exception which occurred:
  	in field locals
  	in field parent
  	in field parent
  	in field caller
  	in field e
  	in field program
  	in field threads
  	in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@509e61d4
  Finished: FAILURE
  

Here's another context where moving away from foreach was not effective.
I was reading some mercurial repositories with source and subdir (to check out to) from a json file:

for(repomap in jsonrepos.configs.repos) {
    for ( key in repomap.keySet() ){
source = repomap.get(key)['source']
subdir = repomap.get(key)['subdir']
checkout([$class: 'MercurialSCM', credentialsId: '', installation: '(Default)', source: "${source}", subdir: "${subdir}"])
   }

This looked nice and elegant, but I hit this exception noted in this bug, so I removed the foreach loops (I include the json steps here):

def slurper = new JsonSlurper()
def jsonText = readFile 'flow-configs/prebuild.json'
jsonrepos = slurper.parseText( jsonText )
repoCount = jsonrepos.configs.repos.size
println "repositories: ${repoCount}"
for ( i = 0 ; i < repoCount ; i++ ) {
    rmap = jsonrepos.configs.repos[i]
    key = rmap.keySet().toList().getAt(0)
    source = rmap.get(key)['source']
    subdir = rmap.get(key)['subdir']
    println("  source: ${source}  subdir: ${subdir}")
    checkout([$class: 'MercurialSCM', credentialsId: '', installation: '(Default)', source: "${source}", subdir: "${subdir}"])
}

It's fine up to the println statement. If you comment out the checkout line, it's all good and prints all the repsitories and subdir info, but if I uncomment out the checkout line I get this exception, which is similar to the rest reported except for the slurper part (which is curious).
This may be a different bug(???), but the stack trace seems to be the same (except the json.JsonSlurper) as other bugs referred to as another instance of this bug.

java.io.NotSerializableException: groovy.json.JsonSlurper
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:1777)
at java.util.HashMap.writeObject(HashMap.java:1354)
at sun.reflect.GeneratedMethodAccessor199.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.jboss.marshalling.reflect.SerializableClass.callWriteObject(SerializableClass.java:271)
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.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.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:2434)
at sun.reflect.GeneratedMethodAccessor206.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.jboss.marshalling.reflect.SerializableClass.callWriteObject(SerializableClass.java:271)
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.writeObject(RiverWriter.java:132)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgram(CpsThreadGroup.java:344)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgram(CpsThreadGroup.java:328)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:303)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$000(CpsThreadGroup.java:71)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:180)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:178)
at org.jenkinsci.plugins.workflow.cps.CpsVmExecutorService$2.call(CpsVmExecutorService.java:47)
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)
Caused by: an exception which occurred:
in field locals
in field parent
in field parent
in field caller
in field e
in field program
in field threads
in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@​509e61d4
Finished: FAILURE

[jenkins-infra-bot]

jglick:

• Original comment link
• Raw content of original comment:

  ssides unrelated user error. You cannot use an unserializable class such as JsonSlurper from a flow script unless it is contained entirely within a method marked @NonCPS. See the tutorial.
  

ssides unrelated user error. You cannot use an unserializable class such as JsonSlurper from a flow script unless it is contained entirely within a method marked @​NonCPS. See the tutorial.

[jenkins-infra-bot]

svanoort:

• Original comment link
• Raw content of original comment:

  jglick  I've got a workaround for how to handle map iteration with Workflow DSL here.  A bit ugly but it works:
  
  
  
  import com.cloudbees.groovy.cps.NonCPS
  
  @NonCPS
  List<Map.Entry> get_map_entries(map) {
      // This is harder than it seems, toArray doesn't work as expected and there are other gotchas to know
      // Also set iterators are forbidden, so you need an indexed collection
      def myarray = []
      myarray.addAll(map.entrySet())
      return myarray
  }
  
  node {
    def test_envs = [:]
     test_envs["debian:wheezy"] = ["echo goober"]
     def entries = get_map_entries(test_envs)
     
     for (int i=0; i<entries.size(); i++){
         String key = entries.get(i).key
         String value =  entries.get(i).value
         echo "Key $key and value $value"
     }
  }
  
  
  

jglick I've got a workaround for how to handle map iteration with Workflow DSL here. A bit ugly but it works:

import com.cloudbees.groovy.cps.NonCPS

@​NonCPS
List get_map_entries(map) {
    // This is harder than it seems, toArray doesn't work as expected and there are other gotchas to know
    // Also set iterators are forbidden, so you need an indexed collection
    def myarray = []
    myarray.addAll(map.entrySet())
    return myarray
}

node {
  def test_envs = [:]
   test_envs["debian:wheezy"] = ["echo goober"]
   def entries = get_map_entries(test_envs)
   
   for (int i=0; iString key = entries.get(i).key
       String value =  entries.get(i).value
       echo "Key $key and value $value"
   }
}

[jenkins-infra-bot]

svanoort:

• Original comment link
• Raw content of original comment:

  Worth noting (may be logged elsewhere or user error), but trying to do toArray on the entrySet to get an array output easily like so:
  
  
  
  def myarray = map.entrySet().toArray()
  
  
  Will give this error:
  hudson.remoting.ProxyException: groovy.lang.MissingMethodException: No signature of method: [Ljava.lang.Object;.get() is applicable for argument types: (java.lang.Integer) values: [0]
  Possible solutions: getAt(java.lang.Integer), grep(), getAt(java.lang.String), grep(java.lang.Object), getAt(java.util.Collection), getAt(groovy.lang.ObjectRange)
  	at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:55)
  	at org.codehaus.groovy.runtime.callsite.PojoMetaClassSite.call(PojoMetaClassSite.java:46)
  	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:42)
  	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
  	at com.cloudbees.groovy.cps.sandbox.DefaultInvoker.methodCall(DefaultInvoker.java:15)
  	at WorkflowScript.run(WorkflowScript:31)
  	at Unknown.Unknown(Unknown)
  	at __cps.transform__(Native Method)
  	at com.cloudbees.groovy.cps.impl.ContinuationGroup.methodCall(ContinuationGroup.java:69)
  	at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.dispatchOrArg(FunctionCallBlock.java:106)
  	at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.fixArg(FunctionCallBlock.java:79)
  	at sun.reflect.GeneratedMethodAccessor745.invoke(Unknown Source)
  	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  	at java.lang.reflect.Method.invoke(Method.java:497)
  	at com.cloudbees.groovy.cps.impl.ContinuationPtr$ContinuationImpl.receive(ContinuationPtr.java:72)
  	at com.cloudbees.groovy.cps.impl.LocalVariableBlock$LocalVariable.get(LocalVariableBlock.java:33)
  	at com.cloudbees.groovy.cps.LValueBlock$GetAdapter.receive(LValueBlock.java:30)
  	at com.cloudbees.groovy.cps.impl.LocalVariableBlock.evalLValue(LocalVariableBlock.java:22)
  	at com.cloudbees.groovy.cps.LValueBlock$BlockImpl.eval(LValueBlock.java:55)
  	at com.cloudbees.groovy.cps.LValueBlock.eval(LValueBlock.java:16)
  	at com.cloudbees.groovy.cps.Next.step(Next.java:58)
  	at com.cloudbees.groovy.cps.Continuable.run0(Continuable.java:145)
  	at org.jenkinsci.plugins.workflow.cps.CpsThread.runNextChunk(CpsThread.java:164)
  	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:274)
  	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$000(CpsThreadGroup.java:74)
  	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:183)
  	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:181)
  	at org.jenkinsci.plugins.workflow.cps.CpsVmExecutorService$2.call(CpsVmExecutorService.java:47)
  	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)
  Finished: FAILURE
  

Worth noting (may be logged elsewhere or user error), but trying to do toArray on the entrySet to get an array output easily like so:

def myarray = map.entrySet().toArray()

Will give this error:
hudson.remoting.ProxyException: groovy.lang.MissingMethodException: No signature of method: [Ljava.lang.Object;.get() is applicable for argument types: (java.lang.Integer) values: [0]
Possible solutions: getAt(java.lang.Integer), grep(), getAt(java.lang.String), grep(java.lang.Object), getAt(java.util.Collection), getAt(groovy.lang.ObjectRange)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:55)
at org.codehaus.groovy.runtime.callsite.PojoMetaClassSite.call(PojoMetaClassSite.java:46)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:42)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
at com.cloudbees.groovy.cps.sandbox.DefaultInvoker.methodCall(DefaultInvoker.java:15)
at WorkflowScript.run(WorkflowScript:31)
at Unknown.Unknown(Unknown)
at __cps.transform__(Native Method)
at com.cloudbees.groovy.cps.impl.ContinuationGroup.methodCall(ContinuationGroup.java:69)
at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.dispatchOrArg(FunctionCallBlock.java:106)
at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.fixArg(FunctionCallBlock.java:79)
at sun.reflect.GeneratedMethodAccessor745.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.cloudbees.groovy.cps.impl.ContinuationPtr$ContinuationImpl.receive(ContinuationPtr.java:72)
at com.cloudbees.groovy.cps.impl.LocalVariableBlock$LocalVariable.get(LocalVariableBlock.java:33)
at com.cloudbees.groovy.cps.LValueBlock$GetAdapter.receive(LValueBlock.java:30)
at com.cloudbees.groovy.cps.impl.LocalVariableBlock.evalLValue(LocalVariableBlock.java:22)
at com.cloudbees.groovy.cps.LValueBlock$BlockImpl.eval(LValueBlock.java:55)
at com.cloudbees.groovy.cps.LValueBlock.eval(LValueBlock.java:16)
at com.cloudbees.groovy.cps.Next.step(Next.java:58)
at com.cloudbees.groovy.cps.Continuable.run0(Continuable.java:145)
at org.jenkinsci.plugins.workflow.cps.CpsThread.runNextChunk(CpsThread.java:164)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:274)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$000(CpsThreadGroup.java:74)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:183)
at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:181)
at org.jenkinsci.plugins.workflow.cps.CpsVmExecutorService$2.call(CpsVmExecutorService.java:47)
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)
Finished: FAILURE

[jenkins-infra-bot]

jglick:

• Original comment link
• Raw content of original comment:

  The MissingMethodException is probably fixable by using entries[i] rather than entries.get(i).
  

The MissingMethodException is probably fixable by using entries[i] rather than entries.get(i).

[jenkins-infra-bot]

jglick:

• Original comment link
• Raw content of original comment:

  NonCPS need not be imported—Workflow scripts get it by default.
  

NonCPS need not be imported—Workflow scripts get it by default.

[jenkins-infra-bot]

jglick:

• Original comment link
• Raw content of original comment:

  If you use an asynchronous step
  
  
  sh "echo Key $key and value $value"
  
  
  you will see that your workaround does not really work:
  
  Started by user anonymous
  [Workflow] Allocate node : Start
  Running on master in …
  [Workflow] node {
  [Workflow] sh
  [flow] Running shell script
  [Workflow] } //node
  [Workflow] Allocate node : End
  [Workflow] End of Workflow
  java.io.NotSerializableException: java.util.LinkedHashMap$Entry
  	at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:860)
  	at …
  	at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:344)
  	at java.util.HashMap.internalWriteEntries(HashMap.java:1777)
  	at java.util.HashMap.writeObject(HashMap.java:1354)
  	at …
  	at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:344)
  	at java.util.TreeMap.writeObject(TreeMap.java:2434)
  	at …
  	at org.jenkinsci.plugins.workflow.support.pickles.serialization.RiverWriter.writeObject(RiverWriter.java:132)
  	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgram(CpsThreadGroup.java:347)
  	at …
  Caused by: an exception which occurred:
  	in field locals
  	in field parent
  	in field parent
  	in field caller
  	in field e
  	in field program
  	in field threads
  	in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@3e45e287
  Finished: FAILURE
  
  
  Here is a working script:
  
  @NonCPS
  List<List<Object>> get_map_entries(map) {
      map.collect {k, v -> [k, v]}
  }
  node {
     def mymap = [a: 1, b: 2]
     def entries = get_map_entries(mymap)
     for (int i=0; i<entries.size(); i++){
         String key = entries[i][0]
         String value =  entries[i][1]
         sh "echo Key $key and value $value"
     }
  }
  
  
  

If you use an asynchronous step

sh "echo Key $key and value $value"

you will see that your workaround does not really work:

Started by user anonymous
[Workflow] Allocate node : Start
Running on master in …
[Workflow] node {
[Workflow] sh
[flow] Running shell script
[Workflow] } //node
[Workflow] Allocate node : End
[Workflow] End of Workflow
java.io.NotSerializableException: java.util.LinkedHashMap$Entry
	at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:860)
	at …
	at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:344)
	at java.util.HashMap.internalWriteEntries(HashMap.java:1777)
	at java.util.HashMap.writeObject(HashMap.java:1354)
	at …
	at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:344)
	at java.util.TreeMap.writeObject(TreeMap.java:2434)
	at …
	at org.jenkinsci.plugins.workflow.support.pickles.serialization.RiverWriter.writeObject(RiverWriter.java:132)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgram(CpsThreadGroup.java:347)
	at …
Caused by: an exception which occurred:
	in field locals
	in field parent
	in field parent
	in field caller
	in field e
	in field program
	in field threads
	in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@​3e45e287
Finished: FAILURE

Here is a working script:

@​NonCPS
ListObject>> get_map_entries(map) {
    map.collect {k, v -> [k, v]}
}
node {
   def mymap = [a: 1, b: 2]
   def entries = get_map_entries(mymap)
   for (int i=0; iString key = entries[i][0]
       String value =  entries[i][1]
       sh "echo Key $key and value $value"
   }
}

[jenkins-infra-bot]

svanoort:

• Original comment link
• Raw content of original comment:

  Notable limitation:  the closure-based solution can trigger script-security violation if you're running workflow scripts from SCM:
  
  org.jenkinsci.plugins.scriptsecurity.sandbox.RejectedAccessException: Scripts not permitted to use staticMethod org.codehaus.groovy.runtime.DefaultGroovyMethods collect java.util.Map groovy.lang.Closure
  at
  
  Also  probably completely doable to find a non-closure approach to this though, just don't have one in hand right now. 
  

Notable limitation: the closure-based solution can trigger script-security violation if you're running workflow scripts from SCM:

org.jenkinsci.plugins.scriptsecurity.sandbox.RejectedAccessException: Scripts not permitted to use staticMethod org.codehaus.groovy.runtime.DefaultGroovyMethods collect java.util.Map groovy.lang.Closure
at

Also probably completely doable to find a non-closure approach to this though, just don't have one in hand right now.