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From "Mark Thomas" <>
Subject Re: ConcurrentHashMap
Date Sun, 08 Nov 2009 16:51:15 GMT
> From: Ohad Shacham <>
> To:
> Sent: 08/11/09, 14:47:25
> Subject: ConcurrentHashMap
> Hi,
> I noticed that in version 6.0.20 several Hashtables and HashMaps were
> replaced by ConcurrentHashMaps. I have noticed that many Hashtables were not
> replaced; therefore, I assume that a contention detection tool was used to
> identify the contended Hashtables. 
Not to my knowledge.

> I would be happy to know if this is the
> case and also whether a scalability and/or performance improvement was
> achieved by switching these collections with concurrent ones.
Based on general experience I'd say yes, mainly for multi-core machines. In specific cases
I don't recall any measurements or results.

The corresponding comit messages should be the best source of information for individual changes.


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