I don't know when it does it's automatic garbage collection if that's
the only issue.
I tried adding the statement to tell it to garbage collect right after
calling the method to render to PNG, though I believe I heard that
doesn't actually do garbage collection right when that executes.  It
didn't appear to do anything.
I'm running Java 6 Update 24.
 
I tested it straight in Eclipse and even tried debug mode so it takes
longer and watched it create a javaw.exe process in task manager which
just kept going up on memory use.
No matter how slowly I went through the program in debug mode the memory
never went down so I expect that means it didn't garbage collect or the
PNGRenderer is preventing some garbage from getting collected.
The Renderer itself should be created and destroyed in the method that
transforms.
The transform method looks a lot like the PDFRenderer method which works
fine.
Why could I not create and save more than a couple dozen pages in PNG
when I just tested a 1986 page report to PDF?
When I render it to preview I am also rendering it to PDF so I can
generate a print preview screen and be able to send to PDF/printer
without rerunning it, but when I run a test program to generate 91 page
output from Eclipse and watch the java process it creates in the task
manager, memory use just generating a PDF got up to 294 MB while the
preview got over 1 GB.
 

________________________________

From: Michael Rubin [mailto:mru...@thunderhead.com] 
Sent: Wednesday, May 18, 2011 8:24 AM
To: fop-dev@xmlgraphics.apache.org
Subject: Re: Fop Memory Use



Just a wild thought. But is there a way you could possibly get the JVM
to garbage collect between each run? Maybe that might free the memory
up?

Thanks.

-Mike

On 18/05/11 13:20, Eric Douglas wrote: 

        I am using Fop 1.0. 
        I tried using Fop to transform a single document.  When I got a
little over 100 pages my FO file was over 5 MB.  The transform crashed
with a Java heap out of memory error.

        I managed to break the input down, as I'm using embedded code
generating the input programmatically, and the PDF output is a lot
smaller.

        So I'm currently transforming 10 pages at a time, setting the
initial-page-number to the next sequence (1, 11, 21, etc).

        Then I save all the generated PDFs in memory and merge them
using pdfbox.  So far this is working great. 

        I tried to do the same thing with the PNGRenderer, just calling
a method to transform 10 pages at a time and save the output images in
an array.

        The PNGRenderer is created locally in the method.  It should be
getting released when the method ends but the java process never
releases any memory.

        I tested a 90 page report and the memory use was over 1 GB.  I
tested on another machine where the memory limit is apparently lower and
it crashed on page 24.

        Everything about the method to render to PNG is the same as the
method to render to PDF aside from the Renderer. 
        Is there a problem with this renderer or something I could need
to do different? 



                                
Michael Rubin

Developer

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