[JENKINS-31768] dead lock while removing computer #21606

"Handling POST /configSubmit from 10.160.255.74 : RequestHandlerThread[#17137]":
  waiting for ownable synchronizer 0x00007f3a5d901708, (a java.util.concurrent.locks.ReentrantLock$NonfairSync),
  which is held by "Computer.threadPoolForRemoting [#31767]"
"Computer.threadPoolForRemoting [#31767]":
  waiting to lock monitor 0x00007f38ce077bc8 (object 0x00007f3a7c8a10c8, a hudson.plugins.ec2.EC2Computer),
  which is held by "Handling POST /configSubmit from 10.160.255.74 : RequestHandlerThread[#17137]"

"Handling POST /configSubmit from 10.160.255.74 : RequestHandlerThread[#17137]":
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00007f3a5d901708> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
        at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
        at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
        at hudson.model.Queue._withLock(Queue.java:1291)
        at hudson.model.Queue.withLock(Queue.java:1176)
        at hudson.model.Computer.setNumExecutors(Computer.java:837)
        - locked <0x00007f3a7c8a10c8> (a hudson.plugins.ec2.EC2Computer)
        at hudson.model.Computer.kill(Computer.java:792)
        at hudson.slaves.SlaveComputer.kill(SlaveComputer.java:665)
        at hudson.model.AbstractCIBase.killComputer(AbstractCIBase.java:86)
        at hudson.model.AbstractCIBase.updateComputerList(AbstractCIBase.java:205)
        at jenkins.model.Jenkins.updateComputerList(Jenkins.java:1249)
        at jenkins.model.Jenkins.doConfigSubmit(Jenkins.java:2924)
        - locked <0x00007f3a5c073f20> (a hudson.model.Hudson)

"Computer.threadPoolForRemoting [#31767]":
        at hudson.model.Computer.setNumExecutors(Computer.java:830)
        - waiting to lock <0x00007f3a7c8a10c8> (a hudson.plugins.ec2.EC2Computer)
        at hudson.model.Computer.inflictMortalWound(Computer.java:809)
        at hudson.model.AbstractCIBase$2.run(AbstractCIBase.java:199)
        at hudson.model.Queue._withLock(Queue.java:1293)
        at hudson.model.Queue.withLock(Queue.java:1176)
        at hudson.model.AbstractCIBase.updateComputerList(AbstractCIBase.java:169)
        at jenkins.model.Jenkins.updateComputerList(Jenkins.java:1249)
        at jenkins.model.Nodes$2.run(Nodes.java:136)
        at hudson.model.Queue._withLock(Queue.java:1293)
        at hudson.model.Queue.withLock(Queue.java:1176)
        at jenkins.model.Nodes.addNode(Nodes.java:132)
        at jenkins.model.Jenkins.addNode(Jenkins.java:1744)