[workflow-plugin] Null Pointer Failure when launching multiple downstream workflow jobs

[Anshu Arya]

I have a parent workflow job that launches 10-15 downstream workflow jobs with the build step.

Something like this:

for(int i = 0; i < 15; i++) {

  build job: 'downstream_workflow_job', quietPeriod: 0, wait: false

}

When I run this I get this error randomly in some of the downstream job logs, i.e. some downstream jobs complete, but some give this error:

java.lang.NullPointerException
        at org.jenkinsci.plugins.workflow.support.steps.ExecutorStepExecution$PlaceholderTask.finish(ExecutorStepExecution.java:339)
        at org.jenkinsci.plugins.workflow.support.steps.ExecutorStepExecution$PlaceholderTask.access$400(ExecutorStepExecution.java:144)
        at org.jenkinsci.plugins.workflow.support.steps.ExecutorStepExecution$PlaceholderTask$Callback.finished(ExecutorStepExecution.java:370)
        at org.jenkinsci.plugins.workflow.steps.BodyExecutionCallback$TailCall.onSuccess(BodyExecutionCallback.java:114)
        at org.jenkinsci.plugins.workflow.cps.CpsBodyExecution$SuccessAdapter.receive(CpsBodyExecution.java:311)
        at com.cloudbees.groovy.cps.impl.ContinuationGroup.methodCall(ContinuationGroup.java:71)
        at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.dispatchOrArg(FunctionCallBlock.java:106)
        at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.fixArg(FunctionCallBlock.java:79)
        at sun.reflect.GeneratedMethodAccessor433.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at com.cloudbees.groovy.cps.impl.ContinuationPtr$ContinuationImpl.receive(ContinuationPtr.java:72)
        at com.cloudbees.groovy.cps.impl.ContinuationGroup.methodCall(ContinuationGroup.java:71)
        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.GeneratedMethodAccessor433.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.ConstantBlock.eval(ConstantBlock.java:21)
        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:271)
        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)
Finished: FAILURE

This seems odd since the code in ExecutorStepExecution.java has an assert to check for null at line 338:

338: assert runningTask.execution != null && runningTask.launcher != null;
339: runningTask.execution.completed(null);

[Anshu Arya]

Reported at: https://issues.jenkins-ci.org/browse/JENKINS-30759

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