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From Arnaud Masson <amas...@gmail.com>
Subject Re: Many background threads (rawStoreDaemon)
Date Mon, 04 May 2009 13:04:24 GMT
derby@segel.com a écrit :
>> -----Original Message-----
>>>> I have an application that opens several small derby databases (using
>>>> EmbeddedDriver).
>>>> Most of of these instances don't handle many requests.
>>>> The problem is that each instance maintain its own thread
>>>> "derby.rawStoreDaemon".
>>>> Is there a way to use a thread pool shared between instances instead ?
>>>> (There is also a discussion about that here:
>>>> http://osdir.com/ml/apache.db.derby.devel/2005-04/msg00093.html)
>>> I am not aware any progress has been made on this issue, unfortunately.
>> If you think it should be adressed, filing a JIRA issue is a good first
>> step: https://issues.apache.org/jira/browse/DERBY
>> (I don't think there is one filed yet, is it?)
> Ok so if I understand this...
> A person wants to open multiple embedded copies of a database and then
> thread pool the database server connections/controllers of the individual
> database connections.
> Ok, yes there is some merit to this. Unfortunately, you're adding a lot of
> weight to the code that means a larger footprint making it harder to embed.
This is not about connection pool.
This is about the fact that each derby instance maintain a thread that 
is sleeping most of the time (rawStoreDaemon).
It would be better for the footprint to free daemon threads when they 
are not used or to recycle them in a pool (like JDK Executor).

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