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From Andrus Adamchik <>
Subject Re: Non-blocking DataRowStore - need help to test
Date Sat, 03 Mar 2012 19:06:39 GMT
So, anyone had a chance to try it?

My colleagues are working on a test right now. Hopefully will have something next week. Also
I did some more staring at the code involved, and I guess all we are doing here is making
more obvious the lack of guaranteed order of context refresh events. Since cross-context synchronization
was asynchronous already (or as I like to call it - "probabilistically consistent" :)), we
are not changing the behavior that much, just changing the probability.

Still would like to hear the feedback from the field.


On Feb 22, 2012, at 1:54 PM, Andrus Adamchik wrote:

> Here is a potentially disruptive change to Cayenne core:
> (also see )
> This removes the major global lock and has a potential to significantly increase throughput
(which is an issue, see CAY-1124 by Tore for instance). The implementation is based on a previously
untried by us data structure - ConcurrentLinkedHashMap -
. It is used by Apache Cassandra, so presumably it works and can handle the load. I internalized
this code, placing it under org.apache.cayenne.util.concurrentlinkedhashmap.
> I need help with testing though... Maybe someone has any kind of load tests that can
emulate multiple DataContexts attached to a single ServerRuntime and performing various select/modify
operations? Or maybe you are daring enough to place this in production? I will do the same
on my end.
> To give some reassurance, our single-threaded unit tests pass 100% with no changes after
I swapped commons-collections LRUMap to ConcurrentLinkedHashMap. 
> Appreciate feedback on this feature!
> Thanks,
> Andrus

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