On Apr 23, 2010, at 4:22 PM, Michael Lang wrote:

> Don,
> 
> Thanks for the enlightening post.  jconsole is pretty nifty!  I ran the clone 
> script again while watching from jconsole.  I don't see any obvious thrashing 
> of any resources going on.  Here's my stats from the last run.
> 
> heap size: 5k
> max heap size: 65k
> committed memory: 6k
> live threads: 12, peak: 14
> daemon threads: 7, total started: 15
> current classes loaded: 2,364
> total physical memory: 4gb
> committed virtual memory: 1.2gb
> free physical memory: 1.1gb
> 
> Records being cloned: 22k
> columns: 63.  of these, roughly 15 are string columns, all 25 characters or 
> less, 4 are date/time, 5 are floats, and the rest are integers.  four indexes 
> on the table.
> 
> For whatever its worth, the same data can be cloned using Delphi compiled app 
> on Windows XP in about 30 seconds.
> 
> My primary goal is to write a wicked fast cloner in ruby that can really 
> crank through a database.  I'm hoping to scale by either pushing to many 
> threads or multiple servers (a la Pentaho Kettle).  Of course, my better 
> option may very well be to use Kettle, but I thought I'd have a little fun 
> with jruby before diving into Java (which isn't something I'm all that keen 
> on doing). 

You may have found a performance regression in JRuby. If you can reduce it to a 
reproducible test case, you should open a JIRA with the JRuby team. They take 
performance regressions very seriously.

Your original post mentioned comparing dataset.all versus dataset.each. I know 
there is a performance penalty when yielding multiple parameters to a block. I 
think they did some work on that in the JRuby 1.5 branch. You might want to try 
it again with 1.5RC1 to see if that makes a difference.

cr

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