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From "Andrew C. Oliver" <acoli...@apache.org>
Subject Re: Improving POIFS performance
Date Fri, 25 Jul 2003 12:12:32 GMT
On 7/25/03 12:59 AM, "Chris Nokleberg" <chris@sixlegs.com> wrote:

> On Tue, Jul 22, 2003 at 09:14:02PM -0400, Andrew C. Oliver wrote:
>> 2. Metrics proving that its faster/better (it should be theoretically)
> 
> FYI, just did some quick performance tests. They involved simply parsing
> a 50M xls (using POIFS only, no HSSF) and then dumping it out to /dev/null.
> 
> On average POIFS took 1.79 seconds and used 60MB.
> "POIFS2" backed by a RandomAccessFile took 0.82 seconds and used 4MB.
> 
> I'm sure the speed up from not having to allocate the memory, but it is
> nice to know that the memory improvements will not come at the expense
> of performance.
> 
> Interestingly, there's hardly any difference between a buffered
> RandomAccessFile and mmapping the entire thing. The implementation of
> the latter is certainly cleaner (it handles things like endianness for
> you), and maybe it makes a bigger difference on some platforms, but
> right now it's not that compelling.
> 

Excellent!  This is exactly what I was looking for.  Now can you write up
some more detail about the interface?  Take a look at
org.apache.poi.hssf.usermodel.HSSFWorkbook.  You can find the complete
coupling with POIFS.  Its like 5 lines of code or so.  What would change if
we coupled it with POIFS2 just enough to make the two work together?  What
would change to make it fully take advantage of POIFS2?

How is POIFS2 in terms of JavaDoc?  Unit Tests?

-andy


> Chris
> 
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-- 
Andrew C. Oliver
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