[infinispan-dev] ISPN-863 - Thoughts / Questions

[Vladimir Blagojevic]

Hey David,

First of all kudos for taking on such a non-trivial task!

On 11-01-14 12:22 AM, david marion wrote:
>
>    1. Modify configuration in some way so that the following can be
>       specified:
>          1. The percentage value of used JVM memory (i.e. 95) at which
>             entries should be evicted to try and avoid an OOM error.
>          2. The number of items that should be evicted when memory
>             reaches this threshold
>    2. Modify LRU and LIRS Eviction class so that the accessQueue
>       member can be accessed by the new Eviction class so that two
>       access queues don’t have to be maintained.
>    3. Create a new Eviction class, a subclass of  LIRS, where the
>       accessQueue is used from the Eviction strategy the user
>       specifies and the for loop in the execute method is exited when
>       the evicted set equals value from 1.b above.
>    4. Modify DataContainerFactory.construct() to call
>       DefaultDataContainer.boundedDataContainer() regardless of
>       eviction policy. This will always create a BoundedConcurrentHashMap
>

I don't think you have to extend LRU and LIRS, as long as you implement 
EvictionPolicy you are fullfilling the contract. What extending LRU and 
LIRS can do is give you some order in selecting proper elements for 
eviction. I think the precise technical term in research literature is 
"eviction precision".

>   1.
>
>
>    2. Create an instance of the new Eviction class in each segment.
>    3. Modify BoundedConcurrentHashMap.Segment put and replace methods
>       such that when new values are going to be put into the Segment,
>       the memory usage is checked and the execute method is called on
>       the new Eviction class.
>

Sounds right!

>   1.
>
>
> Questions:
>
>    1. What are the implications of using a BoundedConcurrentHashMap
>       instead of a ConcurrentHashMap when maxEntries is set to -1?
>

I think none except you turn on eviction by using BoundedConcurrentHashMap.

>   1.
>
>
> Thoughts
>
>    1. This will not guarantee that an OOM error does not occur. It
>       will attempt to guard against an OOM caused by putting new
>       values into the cache. This will probably be more effective when
>       the cache is being used in client/server mode, and less
>       effective when used in embedded mode as to other code running in
>       the JVM.
>
> -- Dave Marion
>
>

Cheers,
Vladimir
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/infinispan-dev/attachments/20110114/376e2622/attachment-0001.html