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From Patricia Shanahan <p...@acm.org>
Subject Re: Question about JIRA use
Date Sun, 29 Aug 2010 21:46:15 GMT
On 8/29/2010 1:45 PM, Peter Firmstone wrote:
> We've got MultithreadedTC in the test/lib directory for allows for
> specific interleaving of threads to test concurrency issues.
> http://www.cs.umd.edu/projects/PL/multithreadedtc/overview.html

Very, very interesting. One of my projects is an attempt to wrap a 
ServiceDiscoveryManager in stub versions of the classes with which it 
interacts, so that I can force lots of events to happen as close as 
possible to the same time. That library might make it possible to force 
specific test cases.

I want to do the same to JoinManager, especially so that I can force 
retries, which do not seem to be being tested.

> Probably best wait till I've got the bug sorted though.
> An update on progress:
> It appears I've sorted the Null pointer issue and the Serialization
> issue, so I'm no longer getting exceptions, however I'm still getting
> test failures, in the ServiceDiscoveryManager, which appear related to
> timing issues, counting events etc.
> I integrated Brian's patch, but that fix isn't related to this
> particular case.
> The next step over the coming week, will be to go back to the stable
> build and incrementally add recent changes, including those I have
> locally now, so I can pinpoint problem causes.

One of the unfortunate things about timing problems is that a perfectly 
valid change can unmask a latent concurrency bug. That is why I've held 
off on pushing a new TaskManager while I'm unsure about the correctness 
of SDM and JoinManager's use of TaskManager.

> Did you want me to update my current local changes to SVN? I've been
> holding off, since additional changes that haven't solved the problem,
> won't make the problem any clearer to those trying to solve it.

If you have fixes for problems you do understand, I would vote for 
checking them in.


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