Hi, Dear Mike, since you said "Are there any opinions out there on
how to determine if Derby "is busy"? " and it is not good for derby
to eat up all the system resources, I am curious to know presently
how does derby avoid eating up all the system resources if it can't
dertermine it's busy or not?
especially the disk IO and cpu usage.
Thanks.
Raymond
>>From: Mike Matrigali
>>Reply-To: "Derby Development"
>>To: Derby Development
>>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
>>time?
>>
>>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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