java - FOP - how to avoid high memory consumption with very high number of page-sequences? -


how can avoid fop consume growing amount of memory when pages not contain forward-references , < page-sequence> blocks small?

here's test java program feeds fop hand made fo repeats on , on same basic page-sequence:

fo2pdf.java

import java.io.filenotfoundexception; import java.io.fileoutputstream; import java.io.outputstream; import java.io.pipedinputstream;  import javax.xml.transform.result; import javax.xml.transform.source; import javax.xml.transform.transformer; import javax.xml.transform.transformerfactory; import javax.xml.transform.sax.saxresult; import javax.xml.transform.stream.streamsource;  import org.apache.fop.apps.fouseragent; import org.apache.fop.apps.fop; import org.apache.fop.apps.fopfactory; import org.apache.fop.apps.mimeconstants; import org.xml.sax.helpers.defaulthandler;  public class fo2pdf implements runnable {  private pipedinputstream in;  public fo2pdf(pipedinputstream in)  {     this.in = in; }   @override public void run() {     // instantiate fop factory     fopfactory fopfactory = fopfactory.newinstance();     fopfactory.setstrictvalidation(false);      // setup output     outputstream out = null;     try {         out = new fileoutputstream("output.pdf");     } catch (filenotfoundexception e) {         e.printstacktrace();     }      try {         // setup user agent         fouseragent useragent = fopfactory.newfouseragent();         useragent.setconservememorypolicy(true);          fop fop = fopfactory.newfop(mimeconstants.mime_pdf, useragent, out);          // setup jaxp using identity transformer         transformerfactory factory = transformerfactory.newinstance();         transformer transformer = factory.newtransformer();           // setup input stream         source src = new streamsource(in);          // resulting sax events (the generated fo) must piped through fop         defaulthandler defaulthandler = (defaulthandler) fop.getdefaulthandler();         result res = new saxresult(defaulthandler);          // start fop processing         transformer.transform(src, res);      } catch (exception e) {         e.printstacktrace();     }     } }

feedfo.java

import java.io.ioexception; import java.io.pipedinputstream; import java.io.pipedoutputstream;   public class feedfo {   public static void main(string args[]) throws ioexception, interruptedexception {      // instantiate , connect pipes     pipedinputstream in = new pipedinputstream();     pipedoutputstream out = new pipedoutputstream(in);      // fo2pdf - instantiate , start consuming stream     fo2pdf fo2pdf = new fo2pdf(in);     thread fo2pdfthread = new thread(fo2pdf, "fo2pdf");     fo2pdfthread.start();      /*      <fo:root xmlns:fo="http://www.w3.org/1999/xsl/format">         <fo:layout-master-set>             <fo:simple-page-master master-name="a4" page-width="210mm" page-height="297mm">                 <fo:region-body/>             </fo:simple-page-master>         </fo:layout-master-set>       */     out.write(("<fo:root xmlns:fo=\"http://www.w3.org/1999/xsl/format\"><fo:layout-master-set>" +             "<fo:simple-page-master master-name=\"a4\" page-width=\"210mm\" page-height=\"297mm\">" +             "<fo:region-body/></fo:simple-page-master></fo:layout-master-set>").getbytes());       for(int i=0; i<100000000; i++) {          // sleep 3 seconds every 50000 page-sequences make sure consumer faster producer         if(i % 50000 == 0) {             thread.currentthread().sleep(3000);         }          /*          <fo:page-sequence xmlns:fo="http://www.w3.org/1999/xsl/format" master-reference="a4">             <fo:flow flow-name="xsl-region-body">                 <fo:block/>             </fo:flow>         </fo:page-sequence>          */         out.write(("<fo:page-sequence xmlns:fo=\"http://www.w3.org/1999/xsl/format\" master-reference=\"a4\"><fo:flow flow-name=\"xsl-region-body\"><fo:block/></fo:flow></fo:page-sequence>").getbytes());     }      out.write("</fo:root>".getbytes());     out.flush();     out.close();      fo2pdfthread.join();      system.out.println("exit"); } }

as notice, fop writes disk pdf page-sequence has been closed. means pages (should?) not being kept memory. but, memory keeps growing , growing. 256mb heap size, generation stops @ 150000 page-sequences.

why happening?

i suspect that, despite sleep call, producer working faster consumer , piped stream filling memory. 2 ways can think of fix this:

option 1 use blockingqueue instead of piped stream.

option 2 add public boolean pipeisfull() method fo2pdf returns true if in.available() exceeds, dunno, 2mb. main loop sleep 500ms or whatever if pipeisfull() true.

also, way reduce memory consumption is

byte[] bytes = ("<fo:page-sequence xmlns:fo=\"http://www.w3.org/1999/xsl/format\" master-reference=\"a4\"><fo:flow flow-name=\"xsl-region-body\"><fo:block/></fo:flow></fo:page-sequence>").getbytes(); for(int i=0; i<100000000; i++) {     ...     out.write(bytes); }

i don't know how significant of impact have (it'll reduce couple gb, that's peanuts compared fo2pdf using), can't hurt.


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