[infinispan-dev] ISPN-863 proposal

[Vladimir Blagojevic]

Yes you are accessing the lock-free queue but you are also locking a 
segment repeatedly to remove each entry selected for eviction 
(MemoryGuard#evict). While this might not be the end of the world it 
will cause lock contention.

Regards,
Vladimir
On 11-01-31 12:37 PM, david marion wrote:
>
>   As a user I'm not tied to any specific implementation (I just want 
> the feature), but I 'll have to look at the code to fully understand 
> your suggestion. I don't have the code in front of me at the moment 
> (I'm at work). However, I don't believe I lock anything specifically. 
> It's very possible that I am doing something that is causing lock 
> contention, can you point me to where this is occurring? I am 
> accessing the same per segment lock free queue that the article mentions.
>
> -- Dave Marion
>
> ------------------------------------------------------------------------
> Date: Mon, 31 Jan 2011 11:57:53 -0300
> From: vblagoje at redhat.com
> To: infinispan-dev at lists.jboss.org
> Subject: [infinispan-dev] ISPN-863 proposal
>
> Dave,
>
> I applaud you for this effort and your implementation and wiki are 
> indeed admirable as you have followed the goals outlined in this JIRA. 
> However, now that I have had an opportunity to look at the final 
> solution I have one concern. We went through a great lengths to design 
> a container that has a low lock contention [1] while maintaining high 
> precision of a sophisticated eviction algorithm. Goals outlined in 
> this JIRA have lead you in a direction to redesign the original 
> proposal. I was wondering if it is possible to use your MemoryMonitor 
> to make a decision whether or not to grow BCHM rather than to check if 
> eviction should be done upon each put invocation? Currently we preset 
> the size of BCHM and we never grow it (i.e. Segment#rehash is never 
> invoked). Maybe this is a place where MemoryMonitor comes as a natural 
> fit. We can keep the current design as outlined in [1] while reaping 
> the benefits of a memory bound resizeable container.
>
>
> WDYT?
>
>
> Regards,
> Vladimir
>
>
>
> [1] 
> http://infinispan.blogspot.com/2010/03/infinispan-eviction-batching-updates.html
>
>
> Dave said:
>
> It took me some time to figure out how to use Git and add some more 
> tests. I have pushed my changes to a topic branch located at 
> https://github.com/dlmarion/infinispan/tree/ISPN-863-master.
>
> Please let me know if you have any questions or concerns. I have put 
> up some documentation at 
> https://github.com/dlmarion/infinispan/wiki/ISPN-863-Implementation
>
> -- Dave Marion
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