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From "Brian Phillips" <>
Subject Re: Curator barriers missing watch events
Date Tue, 25 Mar 2014 22:25:02 GMT
I am using the no arg version! What's the bug?


> On Mar 25, 2014, at 6:23 PM, "Jordan Zimmerman" <> wrote:
> Which version of enter() are you using? I see a potential bug when the no arg version
of enter() is used.
> From: Brian Phillips
> Reply: Brian Phillips
> Date: March 25, 2014 at 4:19:36 PM
> To: Jordan Zimmerman
> Subject:  Re: Curator barriers missing watch events 
>> Good idea, but yes I am. The connection state doesn’t change while I’m executing
the barrier code. It seems to be some kind of race condition I think, as sometimes it work
and sometimes it doesn’t. I’ve looked through the recipe code and it looks good as far
as I can tell though. I’m practically pulling my hair out at this point.
>> I may try a non-curator zookeeper only barrier tomorrow. See if that works. Or I
may start trying to debug the zookeeper client, see if its actually getting the watches but
not delivering them.
>> _B
>>> On Mar 25, 2014, at 4:54 PM, Jordan Zimmerman <>
>>> Are you setting a ConnectionStateListener? If the connection gets SUSPENDED or
LOST then you’d need to reinitialize your barrier.
>>> -JZ
>>> From: Brian Phillips
>>> Reply:
>>> Date: March 25, 2014 at 2:51:42 PM
>>> To:
>>> Subject:  Re: Curator barriers missing watch events 
>>>> I have tried writing a test program which launches two programs in the same
manor, each makes a connection then loops over barriers with a Thread.sleep(random) in-between.
This run indefinitely and everything works out fine.
>>>> I have also tried writing my own barrier, which uses a SharedCount, where
each guy tries to increment it until it hits a memberQty. This too missed watch events and
does not work properly.
>>>> It’s almost as if something else that I’ve done during the running of
my program has broken zookeepers watch events somehow. Is there any good way to debug watch
events in general? I’ve tried to look at the DEBUG output for my zookeeper server log, but
it looks the same for the working vs non-working barriers...
>>>> _B
>>>>> On Mar 25, 2014, at 3:42 PM, Jordan Zimmerman <>
>>>>> Unfortunately, the barrier recipes aren’t widely used (from what I
know). So, there may well be a bug. If you could get a test to show the problem that would
be ideal.
>>>>> -JZ
>>>>> From: Brian Phillips
>>>>> Reply:
>>>>> Date: March 25, 2014 at 2:38:40 PM
>>>>> To:
>>>>> Subject:  Curator barriers missing watch events 
>>>>>> Hi guys, 
>>>>>> I’ve been integrating curator into my project and have recently
run into an issue I just can’t seem to make sense of. 
>>>>>> I’m running two JVMs on the same host machine, each with their
own curator connection. At the beginning of my program I’m using the DistributedDoubleBarrier
recipe, and once again at the end of my program. A bunch of work is done in-between, including
zookeeper set/get/watches of other nodes. 
>>>>>> I’m finding that the first double barrier, everyone always making
it through. The job-end barrier, sometimes everyone gets through, but more often than not
one of the programs hangs in enter's wait(), and never gets the watch event for the ready
path which notifies it to proceed. If I look in zookeeper, I can see that the ready path is
actually set in there. 
>>>>>> It would seem that the watch for one of the programs just never triggers.

>>>>>> To simplify debugging, I’ve set both double barriers to only ever
call enter() and not leave(). Both barriers have their own separate path. 
>>>>>> Also, the program never shuts down or disconnects from zookeeper.
It just sleeps infinitely after it gets out of the final barrier. 
>>>>>> Any idea on how to debug this issue? I don’t mind hacking up zookeeper/curator
code to insert my own debugging statements if it comes to that. 
>>>>>> _Brian=
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