Hi -

On Fri, Mar 12, 2010 at 5:15 AM, Knut Anders Hatlen <Knut.Hatlen@sun.com> wrote:
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.

I wonder whether all these instances in the same VM can be configured to have their own distinct storage, and whether that's the configuration used in the above case.

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 DERBY-4210).

However, can the background threads issue be avoided if all these instances have their own distinct "connection" and "storage"?

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

Yes, it would be good to hear from others who may have tried it.
Hope this helps,

Knut Anders

Yes, it does.
I really appreciate your taking the time to write your note.