[JENKINS-1390] deadlock #24130

I had a deadlock while submitting the Hudson configuration page.
After this I could not access any page.


Found one Java-level deadlock:
=============================
"Executor #0 for master":
  waiting to lock monitor 0x00a89eb4 (object 0x0608cce0, a hudson.model.Hudson),
  which is held by "btpool0-2"
"btpool0-2":
  waiting to lock monitor 0x00a8a014 (object 0x06095c70, a hudson.model.Queue),
  which is held by "Executor #0 for master"

Java stack information for the threads listed above:
===================================================
"Executor #0 for master":
        at hudson.model.Hudson.getDynamicLabels(Hudson.java:1200)

	
waiting to lock <0x0608cce0> (a hudson.model.Hudson)
        at hudson.model.Hudson.getAssignedLabels(Hudson.java:1185)
        at hudson.model.Label.getNodes(Label.java:48)
        at hudson.model.Label.contains(Label.java:93)
        at hudson.model.Queue.choose(Queue.java:414)
        at hudson.model.Queue.pop(Queue.java:329)
	
locked <0x06095c70> (a hudson.model.Queue)
        at hudson.model.Executor.run(Executor.java:63)
"btpool0-2":
        at hudson.model.Queue.scheduleMaintenance(Queue.java:464)
	
waiting to lock <0x06095c70> (a hudson.model.Queue)
        at hudson.model.Hudson.updateComputerList(Hudson.java:564)
        at hudson.model.Hudson.doConfigSubmit(Hudson.java:1428)
	
locked <0x0608cce0> (a hudson.model.Hudson)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:585)
        at org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:103)
        at org.kohsuke.stapler.Function.bindAndinvoke(Function.java:59)
        at org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:63)
        at
org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30)
        at org.kohsuke.stapler.Stapler.invoke(Stapler.java:361)
        at org.kohsuke.stapler.Stapler.invoke(Stapler.java:298)
        at org.kohsuke.stapler.Stapler.service(Stapler.java:98)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
        at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:491)
        at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1074)
        at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:88)
        at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1065)
        at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:365)
        at
org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:185)
        at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
        at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:689)
        at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:391)
        at
org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:146)
        at
org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
        at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139)
        at org.mortbay.jetty.Server.handle(Server.java:285)
        at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:457)
        at
org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:765)
        at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:628)
        at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:209)
        at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:357)
	
locked <0x065a6e38> (a org.mortbay.jetty.HttpConnection)
        at
org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:329)
        at
org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:475)



Found 1 deadlock.