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From Patricia Shanahan <p...@acm.org>
Subject Re: Progress, and a problem
Date Sun, 05 Dec 2010 18:54:42 GMT
I took a quick look at GigaSpaces, and I don't think it meets the 
minimum requirements for a River outrigger replacement.

A satisfactory replacement must have Apache-like binary licensing for a 
version that is no more restricted than outrigger, so that any River 
user who depends on outrigger now, or might depend on it in the future, 
can use the replacement just as freely. Open source would also be very 
desirable, to enable future River-specific tuning and enhancements.

As far as I can tell, GigaSpaces is a closed source commercial product 
with a community edition that is free but restricted to a single node. 
According to http://www.gigaspaces.com/LatestProductVersion, the 
community edition "... is useful for testing, development and 
small-scale deployments.".

Thanks for the suggestion, but I don't think you understood the 
requirements.

Patricia


On 12/4/2010 11:57 AM, Shay Hassidim wrote:
> Patricia,
> I suggest you to try the GigaSpaces implementation.  We solved this issue long time ago.
> We have a free community edition, so you can download it and use it in production.
> Take a look also on our exclusive locking option. You might find it useful.
> Shay
>
> ----- Original Message -----
> From: Patricia Shanahan<pats@acm.org>
> To: river-dev@incubator.apache.org<river-dev@incubator.apache.org>
> Sent: Thu Dec 02 23:27:15 2010
> Subject: Progress, and a problem
>
> I'm currently hunting an intermittent bug found by the test
> qa/src/com/sun/jini/test/impl/outrigger/matching/StressTestWithShutdown.td
>
> After a failure on Hudson, I modified the .td file to make it fail more
> often by increasing the number of entries (10,000), readers (1000), and
> writers (1000).
>
> The writers write entries in an OutriggerServerImpl JavaSpace. The
> readers read, and then take, entries that the writers wrote. Sometimes,
> a reader fails to find an entry a writer claims to have written, causing
> a timeout.
>
> The outrigger implementation depends on the class FastList which seems
> to use the infamous Double Checked Locking idiom
> (http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html)
>
> The good news is that any memory model related error in FastList, or the
> related class EntryHolder, would be a plausible cause of the observed
> symptom. The bad news is that FastList and EntryHolder seem to have been
> written to be very aggressively parallel, possibly by someone who was
> only familiar with sequentially consistent memory. :-(
>
> Usually, it is easy to fix a problem once it has been located. This may
> be a bit more difficult, especially because I assume the parallelism is
> needed for acceptable JavaSpace performance.
>
> Patricia
>
>
>


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