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From Michael André Pearce (Commented) (JIRA) <>
Subject [jira] [Commented] (DIRECTMEMORY-63) Investigate removing the need for an on heap map to store keys/pointers.
Date Sun, 19 Feb 2012 09:50:34 GMT


Michael André Pearce commented on DIRECTMEMORY-63:

I would treat your cache like a hashmap (its the way essentially i view it for this stuff
to keep my head around the bigger picture sometimes), if someone uses java hashmap, it is
expected on the user that the keys hash is unique, i dont think you should be worrying about
this, if a user mucks up their hashing, then it is the same issue they would get using a simple
> Investigate removing the need for an on heap map to store keys/pointers.
> ------------------------------------------------------------------------
>                 Key: DIRECTMEMORY-63
>                 URL:
>             Project: Apache DirectMemory
>          Issue Type: Improvement
>            Reporter: Michael André Pearce
> On performance testing and monitoring jvm heap allocation, it became clear that as the
off heap elements increased so did the on heap used memory. This is because DirectMemory is
storing keys and pointers in the heap meaning that the cache isn't fully off heap, and on
heap memory will increase linearly with elements in the cache.
> An idea maybe is to look into using a key's hash for location on a separate single off
heap buffer to store the main heaps pointers.

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