[jboss-user] [JBoss Cache: Core Edition] - Re: Config Question

lovelyliatroim do-not-reply at jboss.com
Thu Jul 10 08:29:54 EDT 2008


Forgot something

I see also alot of these print outs for my cache using the ExpirationPolicy

anonymous wrote : 
  | 14:09:53 [EvictionTimer-0] WARN  eviction.ExpirationAlgorithm  - Unable to remove nodes to reduce region size below 5000.  Set expiration for nodes in this region
  | 

Now my problem with that is that the region its talking about would only have 2-3 nodes in this region but i get the above output every time the expiration policy runs. Why is this??

I think i kind of know the reason but cant say for sure but here is what i am doing


I have a branch called "root/a", i configure the expiration policy for the region "root/a" to be allowed to have 5000 nodes.

When an items are added to the branch "root/a" it can look like so
"root/a/b/c/1"
"root/a/b/c/2"
"root/a/d/c/1"

Now the expiration key is only added to the very last node, so in this case the numeric values. So when eviction kicks in and nodes are valid for eviction it will only evict the numerical nodes, so after eviction i have the following 
"root/a/b/c"
"root/a/b/c"
"root/a/d/c"

Now why would i keep getting that warning message when i am not exceeding the limit configured for that region? 

Another problem i have with the above strategy for my expiration policy is that i end up with dead branches after eviction i.e the data item i need is evicted but the path to reach it lives on. So take for example

"root/a/b/c/1"
And the data item i want to cash is in node "1", after eviction my tree looks like so
"root/a/b/c"

Essentially the nodes "b" and "c" are dead wood, the data item has been evicted but the path lives on. Is there a better approach to this??

A thought would be to use the path keys on one node level so for example
"root/a/b-c-1"

Which i have no problem in doing but how does the performance compare for locating an item??So you could say depth vs breath, which is the quickest for getting a dataitem??

Any other approaches that i could use??


Thanks Guys,
LL





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