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From Andreas Veithen <>
Subject Re: [Axiom] Encountered OOM issue when service.xml has ServiceTCCL parameter.
Date Thu, 18 Sep 2014 21:41:02 GMT
These maps are of type WeakHashMap<ClassLoader,XMLInputFactory> and
WeakHashMap<ClassLoader,XMLOutputFactory>. WeakHashMaps create memory leaks
if there are value having strong references to their corresponding keys.
For the maps maintained by StAXUtils this would mean that the
XMLInputFactory and/or XMLOutputFactory implementation is loaded by the
class loader used as key. I don't see why this would be the case for the
MultiParentClassLoader created by AbstractMessageReceiver because it simply
delegates to a set of parent class loaders and doesn't load any classes

Can you provide any evidence that there are XMLInputFactory or
XMLOutputFactory instances with strong references to a


On Wed Sep 17 2014 at 5:26:19 PM Geeth Munasinghe <>

> Hi all,
> We are using axis2-1.6.1 version, it uses axiom 1.2.11 version, We
> recently encountered a OOM problem with two services which uses ServiceTCCL
> parameter. We are using this parameter because both those services use
> spring and hibernate with them. Scenario is one service is calling the
> other service. So one service acts as the client.
> We analyzed the heap dumps and found out that OOM issue was caused by
> StAXUtils class. There are few weakhashmaps used in that class. Two of
> them are
>    1. inputFactoryPerCLMap
>    2. outputFactoryPerCLMap
> And those two weak hashmaps has other weak hashmaps inside of them. Those
> inner hashmaps cause the issue.
> We found out that when we use ServiceTCCL parameter  in the service.xml,
> in  [1] of axis2 (line number 152 - 170)
> creates a new class loader object of the MultiParentClassLoader [2] for
> every request. So in StAXUtils class [3] in axiom, methods [4] and [5] uses
> inner  weak hashmaps of inputFactoryPerCLMap,  outputFactoryPerCLMap and
> fill them with the class loader as the key and XMLInputFactory /
> XMLOutputFactory as the value.
> Because every request gets a new class loader object of the
> MultiParentClassLoader, their hash values are different. So they are keep
> getting filled into those inner weak hash maps. Because the same key
> (classloder instance) gets inserted into both weak hashmaps, garbage
> collector does not remove them. So server goes OOM, When we analyze the
> heap dumps we found out that java.util.WeakHashMap fills over 80% of the
> memory when it goes OOM.
> I have made fix in StAXUtils in axiom as follows.
> Instead map.get(cl) I change it to map.get(cl.getClass().getName())
> Instead map.put(cl, factory) I changed it to
> map.put(cl.getClass().getName(), factory)
> I have attached the fix (svn diff) here with email. I am not sure I have
> done the correct fix for the issue. But I found that it solves my problem.
> Can some one please verify weather I have done the correct fix.
> Please consider that upgrading to new axis2 is not a solution for us at
> the moment.
> [1]
> [2] org.apache.axis2.classloader.MultiParentClassLoader
> [3]
> [4] getXMLInputFactory_perClassLoader(StAXParserConfiguration
> configuration)
> [5] getXMLOutputFactory_perClassLoader(StAXWriterConfiguration
> configuration)
> Thanks in advance.
> Geeth

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