Re: [infinispan-dev] Fixing ISPN-2384 (data loss with concurrent activation/passivation)
On 11/02/2012 12:45 PM, Galder Zamarreño wrote:
Ok, my suggestion below is working now, but I'm not so sure the
way the activation interceptor works is the correct one.
IMO, an activation, which involves removing an entry from the cache store (and updating
the stats), should only be done when a cache entry has been retrieved from the cache store
and put into the cache, so a special get() operation.
Any operation that retrieves the entry from the cache store and puts it
into the cache should trigger the activation (remove from cache store).
But put/putAll/replace/remove do this. The first step of each of these
retrieves the current value from the cache, to return to the caller.
However, the activation interceptor is going beyond that by removing
from the store when put, replace, putAll, remove.
Remove makes sense. The entry might not be in memory and so you want to remove it from
the store.
But, put, pulAll and replace? These update the in-memory data, and don't really see
why they should remove anything from the store.
With passivation, data should *either* be in-memory, or in the cache
store. Never both.
I mean, if they don't remove it from the store and the cache
crashes, stale data would be returned, unless you're a clustered cache and you'd
retrieve the in-memory data from another node. If they remove the cache store value and
the cache crashes, the data is gone, again unless it's a clustered cache. So why make
an effort removing the entry from store in these situations? It adds time in the critical
path of these operations.
Thoughts?
-Dennis