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From Knut Anders Hatlen <Knut.Hat...@Sun.COM>
Subject Re: # of derby instances embedded in a JVM ...
Date Fri, 12 Mar 2010 13:15:55 GMT
On 03/12/10 01:05 PM, Masood Mortazavi wrote:
> I am wondering about any limitations regarding the number of Derby 
> instances that can be embedded in a JVM ... (assuming adjustments to 
> heap-size, etc., have been made) ...

Hi Masood,

I haven't tried this myself, but I've heard people talking about having 
about 1000 instances in the same JVM and getting them to run reasonably 
well. The main issues were inefficient use of the heap for caching data 
(since each instance has its own page cache) so that each instance would 
have to run with a very small page cache to prevent exhausting the heap, 
and a high number of background threads (this problem is logged as 

Others who have actually tried this might want to add to this or correct 
me if I've got this wrong, though...

Hope this helps,

Knut Anders

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