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From David kerber <>
Subject Re: Performance: switch vs if ... else if
Date Fri, 22 May 2009 15:35:23 GMT
Caldarale, Charles R wrote:
>> From: Christopher Schultz []
>> Subject: Re: Performance: switch vs if ... else if
>> If you find that a tableswitch is /not/ being generated,
> The tableswitch is being generated for the enum switch (rtFields), but not the char switch.
 However, using the enum generates a ton of other invokes that will far outweigh any advantage
of the tableswitch.  It's possible the JIT is optimizing much of that away, but it's hard
to tell without seeing the generated native code (a tricky thing to dig out).
> It's also possible the JIT could reorder the char switch into an indexed jump table even
when javac doesn't, but again we'd need to see the native code to be sure. 
And probably not worth the effort right now unless somebody is just 
curious or doing some deep research.  I've already got an 
order-of-magnitude improvement in my implementation of this piece of 
code, and more than that on the servlet's overall performance.  As a 
result, right now I don't have any way of generating enough load to find 
a bottleneck in the overall servlet (which is a very good thing!!).  
I've got several machines sitting around that I'd probably have to 
configure as a client farm if I'm going to generate significant loads on 
this app now.


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