On Fri, Jun 08, 2007 at 05:31:19PM +0100, Paulo Soares wrote:
> That's the problem of using tools without understanding them. Most GC
> strategies only release memory when it's full. If you only had 128M the
> GC would kick in earlier than with 256M. What I mean is that summing the
> memory taken by all the temporary objects, many of which go out of scope
> before others are created, is not the same as the memory needed to run a
> program.
Paulo,
I think you misunderstand the issue. Let's say you have a 128mb Java
heap. If, during processing, you have to use 129mb of heap all at
once, then GC will not help you. Furthermore, even if many of these
objects are temporary, creating and collecting lots of garbage is NOT
cheap.
The attitude of "Oh, it's Java, I can create millions of temporary
objects and there will be no problem" is dangerous. There is no
substitute for efficient design.
c
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED] On
> > Behalf Of Chad Loder
> > Sent: Friday, June 08, 2007 5:51 PM
> > To: Post all your questions about iText here
> > Subject: Re: [iText-questions] High memory allocation with PdfPTable
> >
> > Paulo,
> >
> > You're kidding, right? What if the Java heap is only 128mb?
> >
> > c
> >
> > On Fri, Jun 08, 2007 at 03:41:58PM +0100, Paulo Soares wrote:
> > > What's the problem? The GC takes care of that.
> > >
> > > Paulo
> > >
> > > > -----Original Message-----
> > > > From: [EMAIL PROTECTED]
> > > > [mailto:[EMAIL PROTECTED] On
> > > > Behalf Of greggan1
> > > > Sent: Friday, June 08, 2007 9:17 AM
> > > > To: [email protected]
> > > > Subject: [iText-questions] High memory allocation with PdfPTable
> > > >
> > > >
> > > > Hi
> > > >
> > > > I have tested your
> > > > http://itextdocs.lowagie.com/tutorial/objects/tables/pdfptable
> > > > /index.html#memory
> > > > and analyzed the memory allocation during the build with
> > NuMega from
> > > > Compuware. The result shows that 205 MB are used and about
> > > > 575 thousand
> > > > objects are temporarily created for the result, a pdf with a
> > > > size of 53kb.
> > > > The method BidiLine() used about 182 MB of memory.
> > > >
> > > >
> > > >
> > > > I then tried the older Table class and did the same loop with
> > > > the result
> > > > that 22 MB of memory were allocated and 610 thousand
> > objects created.
> > > >
> > > >
> > > > I'm using itext-2.0.0.jar.
> > > >
> > > >
> > > > Should it be like this? Or is it a bug in PdfPTable? Or
> > > > shouldn't itext be
> > > > used as a server side solution? I'm planning to use this on a
> > > > web site with
> > > > many users creating pdf's but it will make the server running
> > > > very slow. The
> > > > server must garbage collect immediately after a pdf is created.
> > > >
> > > > Temporary Bytes including Children: 210,014,040 Bytes
> > > > Temporary Objects including Children: 590,701
> > > >
> > > > PdfPTable
> > > > Size of PDF: 53 kb
> > > > public void fragmentTable()
> > > > {
> > > > System.out.println("FragmentTable");
> > > > int fragmentsize = 50;
> > > > // step1
> > > > Document document = new
> > > > Document(PageSize.A4.rotate(), 10, 10, 10,
> > > > 10);
> > > > try {
> > > > // step2
> > > > PdfWriter.getInstance(document,
> > > > new
> > > > FileOutputStream("FragmentTable.pdf"));
> > > > // step3
> > > > document.open();
> > > > // step4
> > > >
> > > > PdfPTable table = new PdfPTable(2);
> > > > table.setWidthPercentage(100f);
> > > >
> > > > PdfPCell cell;
> > > > for (int row = 1; row <= 2000; row++) {
> > > > if (row % fragmentsize == 0) {
> > > > document.add(table);
> > > > table.deleteBodyRows();
> > > > table.setSkipFirstHeader(true);
> > > > }
> > > > cell = new PdfPCell(new
> > > > Paragraph(String.valueOf(row)));
> > > > table.addCell(cell);
> > > > cell = new PdfPCell(new
> > > > Paragraph("Hello World"));
> > > > table.addCell(cell);
> > > > }
> > > > document.add(table);
> > > > } catch (Exception de) {
> > > > de.printStackTrace();
> > > > }
> > > > // step5
> > > > document.close();
> > > > }
> > > > Temporary Bytes including Children: 205,371,200 Bytes
> > > > Temporary Objects including Children: 575,385
> > > >
> > > >
> > > >
> > > > The memory allocation is the same if you skip the part with "
> > > > if (row %
> > > > fragmentsize == 0) { ......
> > > >
> > > >
> > > >
> > > > Method: BidiLine.BidiLine()
> > > > Package: com.lowagie.text.pdf
> > > > View Call Graph
> > > > View Source Code
> > > > Execution Count: 8,040
> > > > Temporary Bytes: 182,797,440 Bytes
> > > > Temporary Objects: 80,400
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Table
> > > >
> > > > Size of PDF: 68 kb
> > > > public void oldFragmentTable()
> > > > {
> > > > System.out.println("FragmentTable2");
> > > > int fragmentsize = 50;
> > > > // step1
> > > > Document document = new
> > > > Document(PageSize.A4.rotate(), 10,
> > > > 10, 10, 10);
> > > > try {
> > > > // step2
> > > > PdfWriter.getInstance(document,
> > > > new
> > > > FileOutputStream("FragmentTable2.pdf"));
> > > > // step3
> > > > document.open();
> > > > // step4
> > > >
> > > > Table table = new Table(2);
> > > > table.setWidth(100f);
> > > >
> > > > Cell cell;
> > > > for (int row = 1; row <= 2000; row++) {
> > > > cell = new
> > Cell(String.valueOf(row));
> > > > table.addCell(cell);
> > > > cell = new Cell("Hello World");
> > > > table.addCell(cell);
> > > > }
> > > > document.add(table);
> > > > } catch (Exception de) {
> > > > de.printStackTrace();
> > > > }
> > > > // step5
> > > > document.close();
> > > > }
> > > > Temporary Bytes including Children: 22,476,600 Bytes
> > > > Temporary Objects including Children: 610,873
> > > >
> > > >
> > > >
> > > > Method: PdfDocument.add(com.lowagie.text.pdf.PdfTable, boolean)
> > > > Package: com.lowagie.text.pdf
> > > >
> > > > View Call Graph
> > > > View Source Code
> > > > Temporary Bytes: 6,608,088 Bytes
> > > > Temporary Objects: 191,496
> > > >
> > > > //greggan
>
>
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