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From Patricia Shanahan <p...@acm.org>
Subject Re: Progress, and a problem
Date Fri, 03 Dec 2010 15:43:50 GMT
Gregg Wonderly wrote:
> Many people are using Dan Creswell's Blitz JavaSpaces implementation 
> or commercial versions.  I'm partially inclined to suggest that we 
> should discuss EOL of outrigger at some point. Even though Javaspaces
>  is a large part of what Jini has been recognized for, it has a 
> focused audience and if we don't have someone with knowledge and 
> interest to support outrigger, it may be more of a wart than River 
> can deal with.

Although I have limited multi-processor Java and River experience, I do
have the right general background for that mission. I've got decades of
system performance experience, including finding bottlenecks in
multiprocessor operating systems, I understand memory models, and I have
the academic computer science education to look for and understand the
latest research on concurrent data structures.

On the other hand, if we are merely duplicating functionality that is
already available from other sources, that may not be the best use of my
River time.

> One of the issues that I've found in network intensive applications, 
> is that the latency of communications is so huge compared to code 
> paths, that all active threads will fairly quickly end up hovering on
> top of any use of "synchronized" so that there is always the worst 
> case contention for such protected resources.

Communications latency is something that seriously worries me in the
current QA strategy, in which all components run on the same system. We
are not testing with the sort of timing and contention issues our real
world users will experience. There is a risk of not finding bugs that
only happen with timings induced by communications latency, as well as
not noticing performance regressions.


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