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From "Raymond Raymond" <raymond_de...@hotmail.com>
Subject RE: how does derby avoid eating up all the system resources if it's used embeddedly
Date Wed, 19 Oct 2005 07:38:42 GMT
<html><div style='background-color:'><DIV class=RTE>
<P><BR><BR></P>Hi, Dear Mike, since you said "Are there any opinions
out there on </DIV>how to determine if Derby "is busy"?&nbsp;&nbsp;" and it
is not good for derby
<DIV></DIV>to eat up all the system resources, I am curious to know presently
<DIV></DIV>how does derby avoid eating up all the system resources if it can't
<DIV></DIV>dertermine it's busy or not? <FONT color=#ff0033>especially the
disk IO and cpu usage</FONT><FONT color=#ff0000>.</FONT>
<DIV></DIV>&gt;&gt;From: Mike Matrigali
<DIV></DIV>&gt;&gt;Reply-To: "Derby Development"
<DIV></DIV>&gt;&gt;To: Derby Development
<DIV></DIV>&gt;&gt;Subject: Re: Some idea about checkpoint issue, welcome
to give your
<DIV></DIV>&gt;&gt;Date: Tue, 11 Oct 2005 10:57:08 -0700
<DIV></DIV>&gt;&gt;Are there any opinions out there on how to determine
<DIV></DIV>&gt;&gt;Derby "is busy"?&nbsp;&nbsp;Is there something
better than just having
<DIV></DIV>&gt;&gt;a low priority thread&nbsp;&nbsp;and maybe
some query of cpu vs. elapsed
<DIV></DIV>&gt;&gt;The first problem is that I don't think there are great
<DIV></DIV>&gt;&gt;for this in java.&nbsp;&nbsp;The second problem
is that often Derby is
<DIV></DIV>&gt;&gt;meant to be embedded as part of another application,
so we have
<DIV></DIV>&gt;&gt;to be careful not to implement a standard server based
<DIV></DIV>&gt;&gt;where it is appropriate for the "server" to use up
all resources
<DIV></DIV>&gt;&gt;available (ie. idle time may not really be best used
by derby
<DIV></DIV>&gt;&gt;admin processes).
<DIV></DIV>&gt;&gt;I have not come up with a good answer to this problem,
there are
<DIV></DIV>&gt;&gt;a number of things derby could do if it knew it had
idle time
<DIV></DIV>&gt;&gt;available for it's use.&nbsp;&nbsp;Best I have
come up with is some mode
<DIV></DIV>&gt;&gt;in the system that needs to be set by the application
<DIV></DIV>&gt;&gt;starts up Derby - either derby try's to limit it's
use of idle
<DIV></DIV>&gt;&gt;cycles or it enabled to try and schedule work during
idle time.
<DIV></DIV>&gt;&gt;Raymond Raymond wrote:
<DIV></DIV>&gt;&gt; &gt; I have been thinking of the automatic checkpointing
<DIV></DIV>&gt;&gt; &gt; recently.I also find someone added another
issue about "Use
<DIV></DIV>&gt;&gt; &gt; of idle time for background checkpoint" into
the to-do list.
<DIV></DIV>&gt;&gt; &gt; I think we can consider these two issue together.
I have
<DIV></DIV>&gt;&gt; &gt; some idea about it.
<DIV></DIV>&gt;&gt; &gt;
<DIV></DIV>&gt;&gt; &gt; Instead of doing checkpoint periodically
and trying to tune the
<DIV></DIV>&gt;&gt; &gt; checkpoint interval to achieve best performance,
is it possible
<DIV></DIV>&gt;&gt; &gt; keep the background checkpoint process running
to do checkpoint,
<DIV></DIV>&gt;&gt; &gt; and the DBMS can tune the rate of checkpoint
depending on the
<DIV></DIV>&gt;&gt; &gt; current system situation,e.g. if the system
is busy, derby will
<DIV></DIV>&gt;&gt; &gt; slow down the checkpoint rate and if the
system is not
<DIV></DIV>&gt;&gt; &gt; derby will speed up the checkpoint rate.We
will update the
<DIV></DIV>&gt;&gt; &gt; file periodically to let the DBMS know up
to where we did
<DIV></DIV>&gt;&gt; &gt; Maybe we can call it 'increamental checkpointing'.
In my
<DIV></DIV>&gt;&gt; &gt; this approach can use the disk IO resources
with reason if we
<DIV></DIV>&gt;&gt; &gt; decide the checkpoint rate reasonablly.
<DIV></DIV>&gt;&gt; &gt;
<DIV></DIV>&gt;&gt; &gt; I would like to discuss this issue with everyone.
I am not
<DIV></DIV>&gt;&gt; &gt; sure if this approach is doable or not. If
it is doable, I will
<DIV></DIV>&gt;&gt; &gt; have some further questions about how to
decide the appropriate
<DIV></DIV>&gt;&gt; &gt; checkpoint rate.
<DIV></DIV>&gt;&gt; &gt;
<DIV></DIV>&gt;&gt; &gt; Thanks.
<DIV></DIV>&gt;&gt; &gt;
<DIV></DIV>&gt;&gt; &gt; Yours, Raymond
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