Another experiment I tried today was breaking up the jars and deploying them separately. I had the three Apache dependency jars on the classpath, then deployed openhtml2pdf-core.jar and openthmltopdf-pdfbox.jar and finally my html2pdf function jar.
The function worked, resolving the dependencies. But I wasn't filtering, I was still loading in all the classes in the jars. On Thu, Jan 12, 2017 at 1:44 PM, Kevin Duling <kdul...@pivotal.io> wrote: > I have been looking in to the behavior of loading classes that have been > deployed. When the jar is deployed, the server blindly loads the classes, > searching for Geode Functions. Specifically, walks over the classes in the > jar, loads each one, and checks to see if both Function and Declarable are > implemented. > > Because there's nothing done to limit the classes loaded, this can create > a Class Loader leak, causing an OutOfMemoryException: PermGem (or, now with > java 1.8, OutOfMemoryException: Metaspace) > > I wanted to experiment with the behavior, so I grabbed a copy of an > OpenSource project (openhtmltopdf) and wrapped it in to a function I could > call via the dev REST API. Basically, when the function is called, it'll > read in a simple html document and produce a simple PDF from it. > > The project has several dependencies, which created the first problem. It > was necessary to explode both openhtmltopdf-core.jar and > openhtmltopdf-pdfbox.jar out in to my Function's jar. > > However, there are also external Apache jars that are required: > > - pdfbox-2.0.3.jar > - fontbox-2.0.3.jar > - commons-logging-1.2.jar > > If I create an über.jar that contains all of these dependencies and my > Function, then deploy it, I'm able to execute my Function without any > problems. > > If I make a small change to the loader to accept a pattern to only > actually load my Function class out of the jar, the rest of the classes are > not automatically loaded. This causes ClassNotFound and ClassDefNotFound > exceptions. > > If I start my sever and provide the 3 Apache libraries with the > --classpath option, and have my jar only contain my Function and the > openhtmltopdf project classes, then when I deploy I'm able to run my > function. > > Are there any other scenarios to try out to let the class loader load > what's needed rather than having to build these uber jars or specify > dependencies on the server classpath at startup? I don't know of any way > to dynamically update the classpath once the server is up and running. > > >
