last night I let my hudson server do 42 (sic) builds of ZooKeeper trunk. One 
of this builds failed:

junit.framework.AssertionFailedError: Leader hasn't joined: 5
        at org.apache.zookeeper.test.FLETest.testLE(FLETest.java:312)

I did this many builds of trunk, because in my quest to redo the client netty 
integration step by step I made one step which resulted in 2 failed builds out 
of 8. The two failures were both:

junit.framework.AssertionFailedError: Threads didn't join

I can't find any relationship between the above test and my changes. The test 
does not use the ZooKeeper client code at all. So I begin to believe that 
there are some Heisenbugs, Bohrbugs or Mandelbugs[1] in ZooKeeper that just 
happen to show up from time to time without any relationship to the current 

I'll try to investigate the cause further, maybe there is some relationship 
I've not yet found. But if my assumption should apply, then these kind of bugs 
would be a strong argument in favor of refactoring. These bugs are best found 
by cleaning the code, most important implementing strict separation of 

Wouldn't you like to setup Hudson to build ZooKeeper trunk every half an hour?

[1] http://en.wikipedia.org/wiki/Unusual_software_bug

Best regards,

Thomas Koch, http://www.koch.ro

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