[infinispan-dev] Eviction thread and purging expired entries

[Manik Surtani]

On 22 Jul 2010, at 09:11, Galder Zamarreño wrote:

>>> 
>>> It's not considered here, but I think it'd be hard to figure out that expiration is not in use at runtime. You'd have to track calls with expiration and make sure there's at least one expiration that has not expired. Probably not practical.
>> well spotted! Not hard to implement, and definitely simple for the users, as doesn't need an additional config.
> 
> Not hard to implement? You'd need a separate collection to track those nodes to which expiration has been set, including those nodes that might have evicted from memory but are still present in the cache store (imagine a node with expire=1 day, but for eviction +passivation reasons, it has been moved to cache store after 1 min). On top of that, you'd need to update the collection everytime a node is expired to remove it from there. Then, in every call to purge entries from a cache store, you'd have to check this collection to see whether it's empty or not to decide whether to call purge entries on cache store. The latter is not difficult, but the tracking can get complicated v easily. IMO, not worth it. 


Yeah I agree with Galder.  It gets even more complicated when you take distribution into account since with nodes not having a complete view of global state, a rehash may bring in expirable entries.  Guys, please don't do this.  :)

--
Manik Surtani
manik at jboss.org
Lead, Infinispan
Lead, JBoss Cache
http://www.infinispan.org
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