Found one Java-level deadlock:
=============================
"Thread-5":
  waiting to lock monitor 0x00007f0984170b38 (object 0x0000000706fe3aa8, a hudson.model.RunMap),
  which is held by "Jenkins initialization thread"
"Jenkins initialization thread":
  waiting to lock monitor 0x00007f0988015128 (object 0x00000007066b46c0, a hudson.model.Queue),
  which is held by "Thread-5"

Java stack information for the threads listed above:
===================================================
"Thread-5":
	at jenkins.model.lazy.AbstractLazyLoadRunMap.load(AbstractLazyLoadRunMap.java:688)
	- waiting to lock <0x0000000706fe3aa8> (a hudson.model.RunMap)
	at jenkins.model.lazy.AbstractLazyLoadRunMap.load(AbstractLazyLoadRunMap.java:671)
	at jenkins.model.lazy.AbstractLazyLoadRunMap.getById(AbstractLazyLoadRunMap.java:543)
	at org.jenkinsci.plugins.workflow.job.WorkflowRun$Owner.run(WorkflowRun.java:523)
	at org.jenkinsci.plugins.workflow.job.WorkflowRun$Owner.get(WorkflowRun.java:533)
	at org.jenkinsci.plugins.workflow.cps.CpsStepContext.getFlowExecution(CpsStepContext.java:386)
	at org.jenkinsci.plugins.workflow.cps.CpsStepContext.getProgramPromise(CpsStepContext.java:230)
	at org.jenkinsci.plugins.workflow.cps.CpsStepContext.isReady(CpsStepContext.java:236)
	at org.jenkinsci.plugins.workflow.support.steps.ExecutorStepExecution$PlaceholderTask.run(ExecutorStepExecution.java:262)
	at org.jenkinsci.plugins.workflow.support.steps.ExecutorStepExecution$PlaceholderTask.getDisplayName(ExecutorStepExecution.java:281)
	at org.jenkinsci.plugins.workflow.support.steps.ExecutorStepExecution$PlaceholderTask.getFullDisplayName(ExecutorStepExecution.java:290)
	at hudson.model.LoadBalancer$1.assignGreedily(LoadBalancer.java:107)
	at hudson.model.LoadBalancer$1.map(LoadBalancer.java:97)
	at hudson.model.LoadBalancer$2.map(LoadBalancer.java:148)
	at hudson.model.Queue.maintain(Queue.java:1053)
	- locked <0x00000007066b46c0> (a hudson.model.Queue)
	at hudson.model.Queue$1.call(Queue.java:316)
	at hudson.model.Queue$1.call(Queue.java:313)
	at jenkins.util.AtmostOneTaskExecutor$1.call(AtmostOneTaskExecutor.java:94)
	at jenkins.util.AtmostOneTaskExecutor$1.call(AtmostOneTaskExecutor.java:84)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at hudson.remoting.AtmostOneThreadExecutor$Worker.run(AtmostOneThreadExecutor.java:104)
	at java.lang.Thread.run(Thread.java:745)
"Jenkins initialization thread":
	at hudson.model.Queue.schedule2(Queue.java:639)
	- waiting to lock <0x00000007066b46c0> (a hudson.model.Queue)
	at org.jenkinsci.plugins.workflow.support.pickles.ExecutorPickle.rehydrate(ExecutorPickle.java:67)
	at org.jenkinsci.plugins.workflow.support.pickles.serialization.PickleResolver.rehydrate(PickleResolver.java:68)
	at org.jenkinsci.plugins.workflow.support.pickles.serialization.RiverReader.restorePickles(RiverReader.java:128)
	at org.jenkinsci.plugins.workflow.cps.CpsFlowExecution.loadProgramAsync(CpsFlowExecution.java:401)
	at org.jenkinsci.plugins.workflow.cps.CpsFlowExecution.onLoad(CpsFlowExecution.java:379)
	at org.jenkinsci.plugins.workflow.job.WorkflowRun.onLoad(WorkflowRun.java:300)
	at hudson.model.RunMap.retrieve(RunMap.java:219)
	at hudson.model.RunMap.retrieve(RunMap.java:56)
	at jenkins.model.lazy.AbstractLazyLoadRunMap.load(AbstractLazyLoadRunMap.java:688)
	- locked <0x0000000706fe3aa8> (a hudson.model.RunMap)
	at jenkins.model.lazy.AbstractLazyLoadRunMap.load(AbstractLazyLoadRunMap.java:671)
	at jenkins.model.lazy.AbstractLazyLoadRunMap.getById(AbstractLazyLoadRunMap.java:543)
	at org.jenkinsci.plugins.workflow.job.WorkflowRun$Owner.run(WorkflowRun.java:523)
	at org.jenkinsci.plugins.workflow.job.WorkflowRun$Owner.get(WorkflowRun.java:533)
	at org.jenkinsci.plugins.workflow.flow.FlowExecutionList$1.computeNext(FlowExecutionList.java:59)
	at org.jenkinsci.plugins.workflow.flow.FlowExecutionList$1.computeNext(FlowExecutionList.java:51)
	at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:143)
	at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:138)
	at org.jenkinsci.plugins.workflow.flow.FlowExecutionList$ItemListenerImpl.onLoaded(FlowExecutionList.java:165)
	at jenkins.model.Jenkins.<init>(Jenkins.java:845)
	at hudson.model.Hudson.<init>(Hudson.java:82)
	at hudson.model.Hudson.<init>(Hudson.java:78)
	at hudson.WebAppMain$3.run(WebAppMain.java:222)