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From Berin Loritsch <>
Subject Re: [FYI] Profiling Cocoon...
Date Mon, 07 Oct 2002 23:16:13 GMT
Stefano Mazzocchi wrote:
> Hello people,

> 2) we noticed an incredible use of 
> org.apache.avalon.excalibur.collections.BucketMap$Node. It is *by far* 
> the most used class in the heap. More than Strings, byte[], char[] and 
> int[]. Some 140000 instances of that class.
> The number of bucketmap nodes grows linearly with the amount of 
> different pages accessed (as they are fed into the cache), but even a 
> cached resource creates some 44 new nodes, which are later garbage 
> collected.
> 44 is nothing compared to 140000, but still something to investigate.
> So, discovery #1:
>    BucketMaps are used *a lot*. Be aware of this.

BucketMaps shine when high concurrency is an issue like in web environments.
It is what backs the ECM and Fortress.

BucketMaps are static in size, but the nodes are added when necessary.
During the transfer of ownership for the BucketMap to commons we found a
bug in the hashcode lookup.  As the fix, I suggest upgrading to the commons
version (in CVS).  The Excalibur code will be upgraded ASAP.


"They that give up essential liberty to obtain a little temporary safety
  deserve neither liberty nor safety."
                 - Benjamin Franklin

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