Speed of HSSF

[John Yeung <gallium.arsenide@xxxxxxxxx>]

I hope you'll forgive me for hijacking an old thread, but I have
always wondered how long it actually takes to create Excel files with
HSSF compared to xlwt (using iSeries Python).  I have heard some
people say Java is quite slow on the i, especially older ones; and of
course Python has a reputation for being rather slow as well.  Which
is slower on the i?

On Thu, Jun 28, 2012 at 1:16 PM,  <sjones@xxxxxxxxxxxxxxx> wrote:
> The spread sheet has 25 columns & contains 37249 rows.

On Thu, Jun 28, 2012 at 2:56 PM,  <sjones@xxxxxxxxxxxxxxx> wrote:
> It runs for about 20 minutes - would love for it to run quicker but don't
> have any ideas on how to achieve that.

On Thu, Jun 28, 2012 at 3:02 PM, Scott Klement
<rpg400-l@xxxxxxxxxxxxxxxx> wrote:
> You must have a faster computer than I do :-)  My biggest spreadsheet is
> 14000 rows and 18 columns, and it takes about 30 minutes.  And that's
> using SXSSF (lower memory footprint of XSSF)

The reason I'm dredging this up now is that I've just generated a
spreadsheet with 8131 rows and 97 columns on a model 810 (processor
feature 7409) running V5R2 and iSeries Python 2.3.3, and it took about
15 minutes on a quiet (somewhat after-hours) system.  The resulting
file is about 6 MB.

Very, very roughly speaking (as I have no idea what kind of hardware
the others were using), I'd say this is comparable to and quite
possibly better than HSSF.  So I'm certainly feeling very little
incentive to switch from xlwt to HSSF.

Of course, later in that thread:

On Sun, Jul 1, 2012 at 1:33 PM, Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx> wrote:
> I've been working on a service program that works very similarly to
> HSSF, but doesn't call Java routines at all.  Instead, builds an XLSX
> file (the native Excel format in Excel 2007 and up) by building the
> proper directory structure and the various XML files inside that
> structure, then zipping the whole thing.
>
> I have a ways to go -- but for the document I mentioned earlier (the one
> that took 30 minutes with POI's XSSF) it only takes 30 seconds to build.
>   That's a 60-fold improvement in performance.

Yet again, RPG (I'm assuming he means his new program is completely
done in RPG) proves to be a great performer on the i.

John