# Java.util.concurrent.FutureTask Exception during parallel task

**URL:** <https://community.jenkins.io/t/java-util-concurrent-futuretask-exception-during-parallel-task/13256>\
**Category:** Using Jenkins\
**Tags:** pipeline\
**Created:** [March 12, 2024, 2:51pm UTC](https://community.jenkins.io/t/java-util-concurrent-futuretask-exception-during-parallel-task/13256 "2024-03-12T14:51:05Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![AswAce](https://dub1.discourse-cdn.com/flex013/user_avatar/community.jenkins.io/aswace/32/7379_2.png) [@AswAce](https://community.jenkins.io/u/AswAce)\
**Post date:** [March 12, 2024, 2:51pm UTC](https://community.jenkins.io/t/java-util-concurrent-futuretask-exception-during-parallel-task/13256/1 "2024-03-12T14:51:05Z")

</div>

Hello,  
We have few VM machines that we are using to execute tests parallel  
During one of our stages we are getting:

> an exception which occurred:  
> in field com.cloudbees.groovy.cps.Outcome.normal  
> in object com.cloudbees.groovy.cps.Outcome@6ac77b71  
> in field org.jenkinsci.plugins.workflow.cps.CpsThread.resumeValue  
> in object org.jenkinsci.plugins.workflow.cps.CpsThread@71564d60  
> in field org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.threads  
> in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@a80d8a2  
> in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@a80d8a2  
> Also: org.jenkinsci.plugins.workflow.actions.ErrorAction$ErrorId: 1ced049b-5ba6-43c3-ab5e-28166ec4a8f8  
> Also: an exception which occurred:  
> in field com.cloudbees.groovy.cps.Outcome.normal  
> in object com.cloudbees.groovy.cps.Outcome@5ee722a7  
> in field org.jenkinsci.plugins.workflow.cps.CpsThread.resumeValue  
> in object org.jenkinsci.plugins.workflow.cps.CpsThread@3f3a393  
> in field org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.threads  
> in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@a80d8a2  
> in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@a80d8a2  
> Also: org.jenkinsci.plugins.workflow.actions.ErrorAction$ErrorId: 419a0eb9-2050-495a-961f-b90b587d0e63  
> Caused: java.io.NotSerializableException: java.util.concurrent.FutureTask  
> Also: an exception which occurred:  
> in field com.cloudbees.groovy.cps.Outcome.normal  
> in object com.cloudbees.groovy.cps.Outcome@2d7dbaeb  
> in field org.jenkinsci.plugins.workflow.cps.CpsThread.resumeValue  
> in object org.jenkinsci.plugins.workflow.cps.CpsThread@32169e92  
> in field org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.threads  
> in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@a80d8a2  
> in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@a80d8a2  
> Also: org.jenkinsci.plugins.workflow.actions.ErrorAction$ErrorId: b1d25292-961f-4dd4-9e2d-a2c49339bf66  
> Caused: java.io.NotSerializableException: java.util.concurrent.FutureTask

This issue appears on every run in different VM.

**Jenkinsfile has code:**

> stage(‘Run parallel’) {  
> steps {  
> script {
> 
> ```
> def buildMap = [:]
> [
> 'vm1', 'vm2',......
>                 
> ].each {
> buildMap[branchLabel] = executionStages(logic that is done >parallel)
> 
> ```
> 
> parallel buildMap  
> }

---

<div class="post-metadata">

**Author:** ![mushon-okami](https://dub1.discourse-cdn.com/flex013/user_avatar/community.jenkins.io/mushon-okami/32/10070_2.png) [@mushon-okami](https://community.jenkins.io/u/mushon-okami)\
**Post date:** [June 13, 2024, 8:16pm UTC](https://community.jenkins.io/t/java-util-concurrent-futuretask-exception-during-parallel-task/13256/2 "2024-06-13T20:16:06Z")

</div>

### Example Refactor

Here is an example refactor of your pipeline code to use `@NonCPS` and avoid non-serializable objects:

```auto
Copy codestage('Run parallel') {
    steps {
        script {
            def buildMap = [:]
            ['vm1', 'vm2', ...].each { branchLabel ->
                buildMap[branchLabel] = {
                    executionStages(branchLabel)
                }
            }
            parallel buildMap
        }
    }
}

@NonCPS
def executionStages(branchLabel) {
    // Your logic here
}

```