[infinispan-dev] Eviction thread and purging expired entries

[Galder Zamarreño]

On Jul 21, 2010, at 3:24 PM, Mircea Markus wrote:

> Hi,
> 
> Eviction thread does two things right now:
> - evict stuff from DataContainer
> - purge entries from a CacheStore
> 
> CacheStore.purge might slow down eviction as it is generally an expensive operation. It might not even be needed, if the users don't use expiration. 

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.

> What about: 
> a) making EvictionThread.purgeCacheStore configurable. 
> or/and
> b) use another thread for purging the store. 
> 
> This doesn't came out of the blue, there's a user that has eviction+cache store configured with eviction thread wakeup set to 1 sec - he still gets OOM.
> 
> Wdyt?

I think both are valid actually but let me be more precise.

More than making EvictionThread.purgeCacheStore configurable, I'd make expiration as a whole configurable. So, if user does not use expiration, having expiration=false would:
- Disallow calls to overloaded cache methods taking expiration
- Do not check for expiration when entries are retrieved from memory/cachestore
- Don't do EvictionThread.purgeCacheStore 


> 
> Cheers,
> Mircea
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--
Galder Zamarreño
Sr. Software Engineer
Infinispan, JBoss Cache