I am using PDFBox to convert PDF documents to a series of TIFF images (one for each page). The implementation uses PDFRenderer to render each page. Things work fine when I am processing a single document in a single thread, however when I try to process multiple documents (each in its own thread) I get an OutOfMemoryException. In analyzing the heap dump, I see that this is caused by the images cached in DefaultResourceCache. Objects are added added to the cache in PDResources, which includes a method private boolean isAllowedCache(PDXObject xobject) that is used to determine whether an PDXObject can be cached. I have extended this to filter out COSName.IMAGE, and am now able to process multiple documents in parallel. I'd like to contribute this change back to the community. However prior to adding this, I though some feedback on the filtering mechanism may be appropriate. Some options include: - Always exclude images - Allow user to specify whether images should be cached or not (add a method to PDResource to toggle filtering of images). Default would including caching of images to be backwards compatible. - Defer image caching decision to user through callback. Default callback would cache all images to provide backwards compatibility.
I also wanted to know how best to submit my patch for inclusion. Thanks - viraf
