You STILL use POI 1.1????? ON A 64 bit VM????
The 64 bit being substantially slower on the SAME heap size is unshocking.
The fact that the HP VM is so slow is a bit shocking!
The linear progression of time despite heap adjustment on the Windows
version is iteresting. It probably means that you
need more memory for the same code on the HP. Meaning I would expect a
small decrease in time every time you increase the heap (as
counter intuitive as that seems) with the amount of cells you wrote.
Just because the generational garbage collection has more space to work with
(despite having more to scan, it should do GC LESS often than it would
have to otherwise)
-Andy
Mikael Sitruk wrote:
Hi
I've also recently conducted a performance test on windows and hp platform
on 32&64 bits.
The tests were originally done to check the overhead of a wrapper to POI
which allows sending data in buffer and break excel files according to
criteria (max length field/cell values ...)
I've used poi 1.10.
Basically the 1000 rows test is less than 1 sec, but the tests are up to
750,000 rows.
The results are in the attached excel
Mikael.S
-----Original Message-----
From: Avik Sengupta [mailto:[EMAIL PROTECTED]
Sent: Tuesday, June 14, 2005 16:55
To: [EMAIL PROTECTED]
Cc: [email protected]
Subject: Re: Time to add/update cells
On a 1.8GHz linux (2.6) with jdk1.4.2, I can insert rows at approx 1000
per second. Except for brief pauses due to garbage collection, the rate
is resonably consistent. I've tried inserting 5000 rows with 42 cols
each.
Attached is a graph showing this performance, the behaviour should be
pretty obvious (and its quite what you would expect). The code follows,
tell me I didnt do anything stupid!
public void testPerf() {
HSSFWorkbook wb = new HSSFWorkbook();
HSSFSheet s = wb.createSheet();
HSSFRow r ;
HSSFCell c;
long t = System.currentTimeMillis();
long newT =0;
for (int i=0;i < 5000;i++) {
if (i % 100 == 0 && i>0) {
newT=System.currentTimeMillis();
//System.out.println("Rows " + (i-100) +" to "+i+"
inserted in
" +(newT-t) + " ms - at " + (100000/(newT-t) + " rows per sec"));
System.out.println(100000/(newT-t));
t=newT;
}
r = s.createRow(i);
for (short j=0;j<42;j++) {
c = r.createCell(j);
c.setCellValue(i+j);
}
}
On Tue, 2005-06-14 at 07:44 -0400, [EMAIL PROTECTED] wrote:
Thats some odd time. I achieve much better on my box. First off set
your MINIMUM heap size so that it doesn't grow and shrink. Second off,
make sure the heap is at least 50-60% larger than the high water mark of
usage (due to generational garbage collection. Last off, use the 2.6
kernel. Lastly, I'd like to see that code, it may not be POI at all.
-Andy
Brett Knights wrote:
Hello,
I have recently tried to use POI to add a few thousand rows to a
spreadsheet.
It doesn't make much difference if I start with an almost blank
spreadsheet or one with dummy values in the all the cells that will be
populated on a run of known size.
I have 42 columns.
Operations move fairly quickly for the first 600 to 650 rows and then
slow down considerably.
e.g.
On a test run on a 1GHz Windows machine:
Time to update the first 600 rows takes about 8 seconds.
Time to update the following rows to 1850 takes about 4 minutes. At
around row 700 the code is updating around 13 rows a second.
By row 1800 it's down to 5 rows a second.
On a live run with better hardware than my test setup populating 6500
rows takes close to 25 minutes. This is on a 2GHz Debian machine.
On neither machine does memory use approach the max allocated.
jdk 1.4.2
poi-2.5.1-final-20040804
Any help, tips, pointers etc would be most appreciated. It would make my
life easier if I don't have to redo this as a csv.
TIA
Brett Knights
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SuperLink Software, Inc.
Java to Excel using POI
http://www.superlinksoftware.com/services/poi
Commercial support including features added/implemented, bugs fixed.
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