Hi All,

1)Whenever a change in repo, pull request builder trigger the Jenkins jobs(target branch defined in jobs specification)

2)We are using Jenkins pipeline both frontend and backend test run in parallel.

3) Jenkins will allocate nomad slave to run our frontend and backend task(In Nomad Job template we specify the cpu, memory and docker images to run).

4) We are experiencing the "hudson.remoting.ChannelClosedException:" at frequent times.

Jenkins Console log:

[Backend]    -> 0.0624s Cannot contact jenkins-519afe492c4efa: hudson.remoting.ChannelClosedException: Channel "unknown": Remote call on JNLP4-connect connection from ip-10-0-0-10.ec2.internal/10.0.0.10:44176 failed. The channel is closing down or has closed down[Backend]    -> 0.0624sCannot contact jenkins-519afe492c4efa: hudson.remoting.ChannelClosedException: Channel "unknown": Remote call on JNLP4-connect connection from ip-10-0-0-10.ec2.internal/10.0.0.10:44176 failed. The channel is closing down or has closed down[Frontend] Cannot contact jenkins-519afe4939b540: hudson.remoting.ChannelClosedException: Channel "unknown": Remote call on JNLP4-connect connection from ip-10-0-0-10.ec2.internal/10.0.0.10:34472 failed. The channel is closing down or has closed down[Frontend] Could not connect to jenkins-519afe4939b540 to send interrupt signal to process[Frontend] Cancelling nested steps due to timeout[Pipeline] [Frontend] }[Backend] Could not connect to jenkins-519afe492c4efa to send interrupt signal to process[Backend] Cancelling nested steps due to timeout[Pipeline] [Frontend] // stage[Pipeline] [Frontend] }[Pipeline] [Frontend] // node[Pipeline] [Frontend] }[Pipeline] [Backend] }[Pipeline] [Frontend] // timeout[Pipeline] [Backend] // stage[Pipeline] [Frontend] echo[Frontend] Issue org.jenkinsci.plugins.workflow.steps.FlowInterruptedException[Pipeline] [Frontend] sh[Frontend] Required context class hudson.FilePath is missing[Frontend] Perhaps you forgot to surround the code with a step that provides this, such as: node[Pipeline] [Frontend] stage[Pipeline] [Frontend] { (Publish Reports frontend)[Pipeline] [Backend] }[Pipeline] [Backend] // node[Pipeline] [Backend] }[Pipeline] [Frontend] step[Frontend] Required context class hudson.FilePath is missing[Frontend] Perhaps you forgot to surround the code with a step that provides this, such as: node[Pipeline] [Frontend] echo[Frontend] issue with report frontend org.jenkinsci.plugins.workflow.steps.MissingContextVariableException: Required context class hudson.FilePath is missing[Pipeline] [Frontend] }[Pipeline] [Backend] // timeout[Pipeline] [Frontend] // stage[Pipeline] [Frontend] }[Frontend] Failed in branch Frontend[Pipeline] [Backend] echo[Backend] Issue org.jenkinsci.plugins.workflow.steps.FlowInterruptedException[Pipeline] [Backend] sh[Backend] Required context class hudson.FilePath is missing[Backend] Perhaps you forgot to surround the code with a step that provides this, such as: node[Pipeline] [Backend] stage[Pipeline] [Backend] { (Publish Reports backend)[Pipeline] [Backend] publishHTML[Backend] Required context class hudson.Launcher is missing[Backend] Perhaps you forgot to surround the code with a step that provides this, such as: node[Pipeline] [Backend] echo[Backend] issue with reportbackend org.jenkinsci.plugins.workflow.steps.MissingContextVariableException: Required context class hudson.Launcher is missing[Pipeline] [Backend] }[Pipeline] [Backend] // stage[Pipeline] [Backend] }[Backend] Failed in branch Backend[Pipeline] // parallel[Pipeline] End of PipelineSetting status of 94d5 to FAILURE with url https://sample.example.com/job/nomad-test-PR/47/ and message: 'Failed  'Using context: Automation tests (Run-test)Also:   org.jenkinsci.plugins.workflow.steps.MissingContextVariableException: Required context class hudson.FilePath is missing at org.jenkinsci.plugins.workflow.steps.StepDescriptor.checkContextAvailability(StepDescriptor.java:260) at org.jenkinsci.plugins.workflow.cps.DSL.invokeStep(DSL.java:206) at org.jenkinsci.plugins.workflow.cps.DSL.invokeMethod(DSL.java:153) at org.jenkinsci.plugins.workflow.cps.CpsScript.invokeMethod(CpsScript.java:122) at sun.reflect.GeneratedMethodAccessor601.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93) at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325) at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1213) at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1022) at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:42) at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113) at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:157) at org.kohsuke.groovy.sandbox.GroovyInterceptor.onMethodCall(GroovyInterceptor.java:23) at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onMethodCall(SandboxInterceptor.java:133) at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onMethodCall(SandboxInterceptor.java:120) at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:155) at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:159) at com.cloudbees.groovy.cps.sandbox.SandboxInvoker.methodCall(SandboxInvoker.java:17) at WorkflowScript.distributed_run(WorkflowScript:206) at WorkflowScript.run(WorkflowScript:230)org.jenkinsci.plugins.workflow.steps.MissingContextVariableException: Required context class hudson.FilePath is missing at org.jenkinsci.plugins.workflow.steps.StepDescriptor.checkContextAvailability(StepDescriptor.java:260) at org.jenkinsci.plugins.workflow.cps.DSL.invokeStep(DSL.java:206) at org.jenkinsci.plugins.workflow.cps.DSL.invokeMethod(DSL.java:153) at org.jenkinsci.plugins.workflow.cps.CpsScript.invokeMethod(CpsScript.java:122) at sun.reflect.GeneratedMethodAccessor601.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93) at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325) at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1213) at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1022) at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:42) at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48) at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113) at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:157) at org.kohsuke.groovy.sandbox.GroovyInterceptor.onMethodCall(GroovyInterceptor.java:23) at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onMethodCall(SandboxInterceptor.java:133) at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onMethodCall(SandboxInterceptor.java:120) at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:155) at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:159) at com.cloudbees.groovy.cps.sandbox.SandboxInvoker.methodCall(SandboxInvoker.java:17) at WorkflowScript.distributed_run(WorkflowScript:206) at WorkflowScript.run(WorkflowScript:228) at __cps.transform__(Native Method) at com.cloudbees.groovy.cps.impl.ContinuationGroup.methodCall(ContinuationGroup.java:57) at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.dispatchOrArg(FunctionCallBlock.java:109) at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.fixArg(FunctionCallBlock.java:82) at sun.reflect.GeneratedMethodAccessor404.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at com.cloudbees.groovy.cps.impl.ContinuationPtr$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:83) at com.cloudbees.groovy.cps.Continuable$1.call(Continuable.java:174) at com.cloudbees.groovy.cps.Continuable$1.call(Continuable.java:163) at org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.use(GroovyCategorySupport.java:129) at org.codehaus.groovy.runtime.GroovyCategorySupport.use(GroovyCategorySupport.java:268) at com.cloudbees.groovy.cps.Continuable.run0(Continuable.java:163) at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.access$101(SandboxContinuable.java:34) at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.lambda$run0$0(SandboxContinuable.java:59) at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.GroovySandbox.runInSandbox(GroovySandbox.java:108) at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.run0(SandboxContinuable.java:58) at org.jenkinsci.plugins.workflow.cps.CpsThread.runNextChunk(CpsThread.java:174) at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:332) at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$200(CpsThreadGroup.java:83) at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:244) at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:232) 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:131) at jenkins.util.ContextResettingExecutorService$1.run(ContextResettingExecutorService.java:28) at jenkins.security.ImpersonatingExecutorService$1.run(ImpersonatingExecutorService.java:59) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748)Finished: FAILURE