[jboss-dev-forums] [Design of JBossCache] - Re: Optimistic locking doesn't scale well with large 'flat'

[bstansberry@jboss.com]

"jason.greene at jboss.com" wrote : "manik.surtani at jboss.com" wrote :   trying to get a child node will cache a null in the workspace if the child node doesn't exist - to maintain repeatable_read
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  | Technically we don't have to do this, repeatable read allows phantoms, and they are still possible if the lazy loading occurs after a new child is created.
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  | anonymous wrote : 
  |   | The drawback here is that it allows for s slight difference in semantics from pessimistic locking, due to the lazy locking (copying into workspace) of children .
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  | I don't think there is a difference here. Pessimistic locking already allows phantoms by not forcing a write lock when nodes are added/remove. 

By default, this is true, but there is a flag to acquire a write lock for node add/remove.

anonymous wrote : anonymous wrote : 
  |   | Is this approach workable?
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  | Yes, another option is to just lazy copy the entire map the first time it is actually read.
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In the entity caching use case, the map is 100% sure to be read, so a lazy copy doesn't gain anything.

In terms of entity caching, this should be workable since  lockParentForChildInsertRemove=false for this use case.

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