From what I see, the issue happens because Jenkins tries to unexport ProxyInputStream objects from two sides.

My repro steps:
1) Create a test slave with 20 executors
2) Run the Pipeline script below
3) Interrupt build once it starts performing short stashes

// The map we'll store the parallel steps in before executing hem.
def stepsForParallel = [:]

stage "Prepare stashed file"
node("test") {
    sh "cp /Users/nenashev/Documents/jenkins/demo/jenkins-2.7.1/jenkins.war ."
    for (int i=0; i<10; i++) {
        sh "cp jenkins.war jenkins_${i}.war"
    }
    writeFile file: 'foo.txt', text: 'Hello'
    stash includes: 'foo.txt', name: 'foo_stashed'
    stash includes: '*', name: 'jenkins_stashed'
}


stage "Parallel unstash"
for (int i = 0; i < 19; i++) {
    def step = {
        node("test") {
            ws("ws_$i") {
                unstash includes: '*', name: 'jenkins_stashed'
            }
        }
    }
    stepsForParallel["unstash_$i"] = step
}
    
stepsForParallel["fast_unstash"] = {
    node("test") {
        ws("ws_fast") {
            for (int i=0; i<2000; i++) {
                unstash includes: '*', name: 'foo_stashed'
            }
        }
    }
}

parallel stepsForParallel

Side 1. Remote call releases exports at the end of the call. E.g. if it gets interrupted

Released at Thu Aug 04 13:12:16 MSK 2016
    	at hudson.remoting.ExportTable$Entry.release(ExportTable.java:131)
    	at hudson.remoting.ExportTable$ExportList.release(ExportTable.java:247)
    	at hudson.remoting.UserRequest.releaseExports(UserRequest.java:224)
    	at hudson.remoting.UserRequest.releaseExports(UserRequest.java:220)
    	at hudson.remoting.Channel.call(Channel.java:798)
    	at hudson.FilePath.act(FilePath.java:1007)
    	at hudson.FilePath.act(FilePath.java:996)
    	at hudson.FilePath.untarFrom(FilePath.java:728)
    	at org.jenkinsci.plugins.workflow.flow.StashManager.unstash(StashManager.java:114)

Side 2. When ProxyInputStream gets closed, it sends asynchronous EOF command to the remote side. This EOF also tries to release the allocated object (FileInputStream in my case). By the time the request gets to the remote executor, UserRequest.releaseExports() unexports the object.

ProxyInputStream is nested into RemoteInputStream, which is actually being used for many cases like stdin/stdout propagation in remote calls. So technically any remote call operation may overlap with UserRequest termination handler and cause an overlap in such case.

So the solution would be to either make ProxyInputStream EOF command synchronous or to make it tolerant against race conditions.

Reproducing the issue in tests

The fix has been release in remoting-2.62 and jenkins-2.17

This fix will be part of 2.19.1 LTS naturally.

Code changed in jenkins
User: Bertrand Roussel
Path:
client/pom.xml
http://jenkins-ci.org/commit/swarm-plugin/8ad209aaafad5ec6256aa547702870da083ff6cd
Log:
Upgrade remoting API to 2.62

Version 2.62 contains a fix for the following bugs:

• https://issues.jenkins-ci.org/browse/JENKINS-22853
• https://issues.jenkins-ci.org/browse/JENKINS-23271 (possibly)

This occurs mostly with Java 8.

The remoting version matches with Jenkins 2.18/2.19/2.19.1/2.19.2.

HI There,

We are still seeing this on Jenkins ver. 2.7.1. Is there additional things we can do to troubleshoot. We have also been crashing with permgen errors since upgrade, not sure if related. Please advise if i should reopen this issue. Thanks!

SEVERE: Trying to unexport an object that's already unexported
java.lang.IllegalStateException: Invalid object ID 412 iota=773
at hudson.remoting.ExportTable.diagnoseInvalidId(ExportTable.java:386)
at hudson.remoting.ExportTable.unexportByOid(ExportTable.java:409)
at hudson.remoting.Channel.unexport(Channel.java:641)
at hudson.remoting.UnexportCommand.execute(UnexportCommand.java:43)
at hudson.remoting.Channel$1.handle(Channel.java:501)
at hudson.remoting.SynchronousCommandTransport$ReaderThread.run(SynchronousCommandTransport.java:60)
Caused by: java.lang.Exception: Object was recently deallocated
#412 (ref.0) : object=null type=hudson.remoting.FastPipedOutputStream interfaces=[java.lang.Object]
Created at Thu Feb 02 09:24:16 EST 2017
at hudson.remoting.ExportTable$Entry.<init>(ExportTable.java:99)
at hudson.remoting.ExportTable.export(ExportTable.java:305)
at hudson.remoting.Channel.internalExport(Channel.java:629)
at hudson.remoting.Pipe.writeObject(Pipe.java:158)
at sun.reflect.GeneratedMethodAccessor1141.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at hudson.remoting.UserRequest._serialize(UserRequest.java:189)
at hudson.remoting.UserRequest.serialize(UserRequest.java:198)
at hudson.remoting.UserRequest.<init>(UserRequest.java:64)
at hudson.remoting.Channel.callAsync(Channel.java:807)
at hudson.FilePath.actAsync(FilePath.java:1087)
at hudson.FilePath.read(FilePath.java:1782)
at hudson.plugins.groovy.FileScriptSource.getScriptStream(FileScriptSource.java:52)
at hudson.plugins.groovy.SystemGroovy.perform(SystemGroovy.java:93)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:779)
at hudson.model.Build$BuildExecution.build(Build.java:205)
at hudson.model.Build$BuildExecution.doRun(Build.java:162)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:534)
at hudson.model.Run.execute(Run.java:1741)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:98)
at hudson.model.Executor.run(Executor.java:410)
Released at Thu Feb 02 09:24:16 EST 2017
at hudson.remoting.ExportTable$Entry.release(ExportTable.java:131)
at hudson.remoting.ExportTable.unexportByOid(ExportTable.java:414)
at hudson.remoting.Channel.unexport(Channel.java:641)
at hudson.remoting.ProxyOutputStream$EOF$1.run(ProxyOutputStream.java:366)
at hudson.remoting.PipeWriter$1.run(PipeWriter.java:158)
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at hudson.remoting.SingleLaneExecutorService$1.run(SingleLaneExecutorService.java:112)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:68)
at org.jenkinsci.remoting.CallableDecorator.call(CallableDecorator.java:18)
at hudson.remoting.CallableDecoratorList$1.call(CallableDecoratorList.java:21)
at jenkins.util.ContextResettingExecutorService$2.call(ContextResettingExecutorService.java:46)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: Command ProxyOutputStream.EOF(412) created at
at hudson.remoting.Command.<init>(Command.java:67)
at hudson.remoting.Command.<init>(Command.java:50)
at hudson.remoting.ProxyOutputStream$EOF.<init>(ProxyOutputStream.java:358)
at hudson.remoting.ProxyOutputStream.doClose(ProxyOutputStream.java:177)
at hudson.remoting.ProxyOutputStream.close(ProxyOutputStream.java:173)
at org.apache.commons.io.IOUtils.closeQuietly(IOUtils.java:303)
at org.apache.commons.io.IOUtils.closeQuietly(IOUtils.java:274)
at hudson.FilePath$33.invoke(FilePath.java:1795)
at hudson.FilePath$33.invoke(FilePath.java:1782)
at hudson.FilePath$FileCallableWrapper.call(FilePath.java:2772)
at hudson.remoting.UserRequest.perform(UserRequest.java:118)
at hudson.remoting.UserRequest.perform(UserRequest.java:48)
at hudson.remoting.Request$2.run(Request.java:328)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:72)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at hudson.remoting.Engine$1$1.run(Engine.java:63)
... 1 more
at hudson.remoting.ExportTable.diagnoseInvalidId(ExportTable.java:379)