Re: RFI: concurrent fop instances -- use cases

2013-07-01 Thread Alexios Giotis 
Hi Luis,

It is definitely possible to have different threads using Fop instances created 
from the same FopFactory. In fact, for me this is the typical usage. This is 
like replacing 

 foreach (Doc doc : listOfDocs) {
 File fo = doc.getFOFile();
 File pdf = doc.getPDFFile();
 generateOutput(fo, pdf, fopFactory);

with 

ThreadPoolExecutor executor = new ThreadPoolExecutor(corePoolSize, ...);
for (Doc doc : listOfDocs) {
  executor.submit(new Runnable() {
File fo = doc.getFOFile();
File pdf = doc.getPDFFile();
generateOutput(fo, pdf, fopFactory);
  }
}

It is used to reduce the time required to generate thousands or millions of 
documents.

Fop instances can also be generated from different FopFactory instances. This 
is a workaround I used in the past to avoid some FOP concurrency issues. The 
drawback is increased memory usage and warm-up time as FOP caches are 
referenced from a FopFactory instance.


Alex Giotis



On 1 Jul 2013, at 15:14, Luis Bernardo lmpmberna...@gmail.com wrote:

 
 Hello,
 
 I am investigating the possible caching of layout elements and as part of the 
 investigation I realized that I need to understand how fop instances are 
 managed in real life situations. In particular, I need to know if it is 
 possible to have two concurrent fop instances created from the same fop 
 factory.
 
 This is a typical use case I am familiar with:
 FopFactoryBuilder builder = new FopConfParser(new 
 File(confFile)).getFopFactoryBuilder();
 FopFactory fopFactory = builder.build();
 foreach (Doc doc : listOfDocs) {
 File fo = doc.getFOFile();
 File pdf = doc.getPDFFile();
 generateOutput(fo, pdf, fopFactory);
 }
 
 where:
 
 public static void generateOutput(File fo, File pdf, FopFactory 
 fopFactory) throws IOException, FOPException,
 TransformerException {
 OutputStream out = null;
 try {
 FOUserAgent foUserAgent = fopFactory.newFOUserAgent();
 out = new FileOutputStream(pdf);
 out = new BufferedOutputStream(out);
 Fop fop = fopFactory.newFop(mime, foUserAgent, out);
 TransformerFactory factory = TransformerFactory.newInstance();
 Transformer transformer = factory.newTransformer();
 Source src = new StreamSource(fo);
 Result res = new SAXResult(fop.getDefaultHandler());
 transformer.transform(src, res);
 } finally {
 out.close();
 }
 }
 
 In this case, even though a fop factory can create many fop instances we 
 cannot have more than one in use at at given time.
 
 Is anyone using a different approach where concurrent fop instances are 
 possible?
 
 Thanks,
 Luis

Re: RFI: concurrent fop instances -- use cases

2013-07-01 Thread Luis Bernardo 
Thanks Alex. Your example (different threads using Fop instances created
from the same FopFactory) is exactly the use case I was wondering whether
is was possible.


On Mon, Jul 1, 2013 at 3:35 PM, Alexios Giotis alex.gio...@gmail.comwrote:

 Hi Luis,

 It is definitely possible to have different threads using Fop instances
 created from the same FopFactory. In fact, for me this is the typical
 usage. This is like replacing

  foreach (Doc doc : listOfDocs) {
  File fo = doc.getFOFile();
  File pdf = doc.getPDFFile();
  generateOutput(fo, pdf, fopFactory);

 with

 ThreadPoolExecutor executor = new ThreadPoolExecutor(corePoolSize, ...);
 for (Doc doc : listOfDocs) {
   executor.submit(new Runnable() {
 File fo = doc.getFOFile();
 File pdf = doc.getPDFFile();
 generateOutput(fo, pdf, fopFactory);
   }
 }

 It is used to reduce the time required to generate thousands or millions
 of documents.

 Fop instances can also be generated from different FopFactory instances.
 This is a workaround I used in the past to avoid some FOP concurrency
 issues. The drawback is increased memory usage and warm-up time as FOP
 caches are referenced from a FopFactory instance.


 Alex Giotis



 On 1 Jul 2013, at 15:14, Luis Bernardo lmpmberna...@gmail.com wrote:

 
  Hello,
 
  I am investigating the possible caching of layout elements and as part
 of the investigation I realized that I need to understand how fop instances
 are managed in real life situations. In particular, I need to know if it is
 possible to have two concurrent fop instances created from the same fop
 factory.
 
  This is a typical use case I am familiar with:
  FopFactoryBuilder builder = new FopConfParser(new
 File(confFile)).getFopFactoryBuilder();
  FopFactory fopFactory = builder.build();
  foreach (Doc doc : listOfDocs) {
  File fo = doc.getFOFile();
  File pdf = doc.getPDFFile();
  generateOutput(fo, pdf, fopFactory);
  }
 
  where:
 
  public static void generateOutput(File fo, File pdf, FopFactory
 fopFactory) throws IOException, FOPException,
  TransformerException {
  OutputStream out = null;
  try {
  FOUserAgent foUserAgent = fopFactory.newFOUserAgent();
  out = new FileOutputStream(pdf);
  out = new BufferedOutputStream(out);
  Fop fop = fopFactory.newFop(mime, foUserAgent, out);
  TransformerFactory factory =
 TransformerFactory.newInstance();
  Transformer transformer = factory.newTransformer();
  Source src = new StreamSource(fo);
  Result res = new SAXResult(fop.getDefaultHandler());
  transformer.transform(src, res);
  } finally {
  out.close();
  }
  }
 
  In this case, even though a fop factory can create many fop instances we
 cannot have more than one in use at at given time.
 
  Is anyone using a different approach where concurrent fop instances are
 possible?
 
  Thanks,
  Luis