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From "Raymond Raymond" <raymond_de...@hotmail.com>
Subject how does derby avoid eating up all the system resources if it's used embeddedly
Date Wed, 19 Oct 2005 01:40:19 GMT
Hi, Dear Mike, since you said "Are there any opinions out there on how to 
if Derby "is busy"?  " and it is not good for derby to eat up all the system 
I am curiously want to know presently how does derby avoid eating up all the 
resources if it can't dertermine it's busy or not?



>From: Mike Matrigali <mikem_app@sbcglobal.net>
>Reply-To: "Derby Development" <derby-dev@db.apache.org>
>To: Derby Development <derby-dev@db.apache.org>
>Subject: Re: Some idea about checkpoint issue, welcome to give your idea
>Date: Tue, 11 Oct 2005 10:57:08 -0700
>Are there any opinions out there on how to determine if
>Derby "is busy"?  Is there something better than just having
>a low priority thread  and maybe some query of cpu vs. elapsed
>The first problem is that I don't think there are great tools
>for this in java.  The second problem is that often Derby is
>meant to be embedded as part of another application, so we have
>to be careful not to implement a standard server based approach
>where it is appropriate for the "server" to use up all resources
>available (ie. idle time may not really be best used by derby
>admin processes).
>I have not come up with a good answer to this problem, there are
>a number of things derby could do if it knew it had idle time
>available for it's use.  Best I have come up with is some mode
>in the system that needs to be set by the application which
>starts up Derby - either derby try's to limit it's use of idle
>cycles or it enabled to try and schedule work during idle time.
>Raymond Raymond wrote:
> > I have been thinking of the automatic checkpointing issue
> > recently.I also find someone added another issue about "Use
> > of idle time for background checkpoint" into the to-do list.
> > I think we can consider these two issue together. I have
> > some idea about it.
> >
> > Instead of doing checkpoint periodically and trying to tune the
> > checkpoint interval to achieve best performance, is it possible to
> > keep the background checkpoint process running to do checkpoint,
> > and the DBMS can tune the rate of checkpoint depending on the
> > current system situation,e.g. if the system is busy, derby will
> > slow down the checkpoint rate and if the system is not busy(idle),
> > derby will speed up the checkpoint rate.We will update the control
> > file periodically to let the DBMS know up to where we did checkpoint.
> > Maybe we can call it 'increamental checkpointing'. In my opinion,
> > this approach can use the disk IO resources with reason if we can
> > decide the checkpoint rate reasonablly.
> >
> > I would like to discuss this issue with everyone. I am not
> > sure if this approach is doable or not. If it is doable, I will
> > have some further questions about how to decide the appropriate
> > checkpoint rate.
> >
> > Thanks.
> >
> > Yours, Raymond
> >
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