I spent a good part of yesterday afternoon to track down this problem. I first attached Visual Studio to the hanging JVM. While I can see the JVM source code and Windows API symbols all right, I couldn't figure out how to relate back the code produced by JIT to its Java, so this made the debugging very hard.

What I observed was that Maven's main thread seems to be blocked in WaitForSingleObject kernel API, but I can't figure out what handle it's blocking on. This call appears to come directly from JIT-ed Java code.

The problem disappears if I enable Java debugger support, or if I attach jconsole. So this cannot be a plain Java-level deadlock.

So after that much work, I still coudldn't figure out the root cause.


But I took the advice from mriem@dev.ajva.net anyway, and modified the remoting to use a separate TCP socket, instead of stdin/stdout. This is useful anyway, because sometimes JVM writes out to stdout and that breaks the whole set up, which was one of the known issues.

This commit brings in this change, and in the limited testing so far, this appears to work. So let's hope that it fixes the problem once and for all.


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git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@9612 71c3de6d-444a-0410-be80-ed276b4c234a

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@9611 71c3de6d-444a-0410-be80-ed276b4c234a

My apologies for the delay in handling this.
This change will be in 1.219.



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rolling back the synchronizatoin in closeChannel() for now to avoid NPE as discussed in "hudson 1.217 issue -" Please wait while hudson is getting ready to work..."

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@9511 71c3de6d-444a-0410-be80-ed276b4c234a

public domain version from http://gee.cs.oswego.edu/cgi-bin/viewcvs.cgi/jsr166/src/main/java/util/concurrent/TimeUnit.java?view=markup

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I think this is the safest quickest fix until the proper fix is implemented

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I am unsure as to whether we should expose the closeChannel method on a SlaveComputer and have just one disconnect method, or use this before and after pair of methods to allow for tidy termination...

Also, I think there was a missing synchronized(channelLock) in closeChannel... now I'm wondering if the entire disconnect runnable should hold that lock... but it could be long running!

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backport of JDK 6 version of TimeUnit... it's just too handy to be able to convert from MINUTES, etc

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git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@9472 71c3de6d-444a-0410-be80-ed276b4c234a

See reports like http://www.nabble.com/Missing-Hudson-icons-to17333588.html

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for both smarter scheduling and better slave management. For that, we need to have
a real object to attach information to.



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