Re: Creating objects in the database

William Pietri <[email protected]>
Newsgroups gmane.comp.java.prevayler
Message-ID <[email protected]>
Khayundi, Peter wrote:
>
> Hi William,
>
>  
>
> Thanks for the reply to my query. About the IO, I have ensured that 
> there is no other unnecessary process running on the machine during 
> the operation. And also, about the second problem, I increased the 
> Java heap size to 512MB which should be more than adequate for this 
> operation. Any other ideas that I may try?
>
>  
>

Could necessary processes also write to or read from the same disk? 
Normally if one is doing tests like this, one uses an entirely separate 
disk. That's because people who care about performance use separate 
spindles in production.

Beyond that, correct server optimization is really an OS-dependent 
thing. Looking at your code, I see you're doing each write as a 
transaction. That's fine, but that means performance will vary widely 
depending on how things are tuned. With the default filesystem and 
tuning on my laptop, I get about 8.4ms per transaction, and I can hear 
the drive seeking like crazy. If I eliminate the seeks, the time per 
transaction drops to 0.14ms per transaction, nearly a 60x difference.

Also, have you tried using GC logging to rule out GC activity during 
your runs? Although I agree that 512MB should be more than adequate, 
what I think the JVM should do in the abstract often diverges from what 
it actually gets up to.

William

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