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List:       xalan-dev
Subject:    [jira] [Updated] (XALANJ-2600) Memory leak in TransformerIdentityImpl
From:       Samuel_Brezáni_(JIRA) <jira () apache ! org>
Date:       2016-02-20 11:50:18
Message-ID: JIRA.12940772.1455968769000.101153.1455969018075 () Atlassian ! JIRA
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     [ https://issues.apache.org/jira/browse/XALANJ-2600?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel \
]

Samuel Brezáni updated XALANJ-2600:
-----------------------------------
    Description: 
Hi.

I found a serious memory leak in the Xalan library. It is caused by the \
org.apache.xalan.transformer.TransformerIdentityImpl class.

I try to explain mechanism how the memory leak is caused:

Web application is deployed on SAP NetWeaver AS with Java 1.6 (1.6.0_95). The \
application uses Spring WS library but also another libraries with dependency to \
Xalan library.

When the web service is invoked, then the TransformerIdentityImpl class is used. This \
class is used because it's extends javax.xml.transform.Transformer and it is created \
by Java core method - javax.xml.transform.TransformerFactory.newInstance().


A class com.sun.xml.internal.messaging.saaj.soap.EnvelopeFactory is used for handling \
web services. This object also contains cache (ParserPool) with SAXParser objects \
(com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl). As key for this cache is \
used an application class loader.

EnvelopeFactory object and SAXParserImpl objects are loaded by a system class loader, \
but TransformerIdentityImpl class is loaded by an application class loader.

During handling of web service a method \
org.apache.xalan.transformer.TransformerIdentityImpl.transform(Source, Result) is \
invoked. This method uses SAXParser as a reader. *Problem is that this method \
register self for handling properties (eg: "http://xml.org/sax/handlers/DeclHandler") \
but after processing method doesn't unregister self from SAXParser*. It means that \
objects loaded by the system class loaded has dependencies on objects loaded by the \
application class loader.

Objects are still loaded after application is undeployed because cached SAXParser \
references TransformerIdentityImpl.


I prepared very simple patch to fix this problem. In the attachment is also picture \
which demonstrates situation.

  was:
Hi.

I found a serious memory leak in the Xalan library. It is caused by the \
org.apache.xalan.transformer.TransformerIdentityImpl class.

I try to explain mechanism how the memory leak is caused:

Web application is deployed on SAP NetWeaver AS with Java 1.6 (1.6.0_95). The \
application uses Spring WS library but also another libraries with dependency to \
Xalan library.

When the web service is invoked, then the TransformerIdentityImpl class is used. This \
class is used because it's extends javax.xml.transform.Transformer and it is created \
by Java core method - javax.xml.transform.TransformerFactory.newInstance().


A class com.sun.xml.internal.messaging.saaj.soap.EnvelopeFactory is used for handling \
web services. This object also contains cache (ParserPool) with SAXParser objects \
(com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl). As key for this cache is \
used an application class loader.

EnvelopeFactory object and SAXParserImpl objects are loaded by a system class loader, \
but TransformerIdentityImpl class is loaded by an application class loader.

During handling of web service a method \
org.apache.xalan.transformer.TransformerIdentityImpl.transform(Source, Result) is \
invoked. This method uses SAXParser as a reader. Problem is that this method register \
self for handling properties (eg: "http://xml.org/sax/handlers/DeclHandler") but \
after processing method doesn't unregister self from SAXParser. It means that objects \
loaded by the system class loaded has dependencies on objects loaded by the \
application class loader.

Objects are still loaded after application is undeployed because cached SAXParser \
references TransformerIdentityImpl.


I prepared very simple patch to fix this problem. In the attachment is also picture \
which demonstrates situation.


> Memory leak in TransformerIdentityImpl
> --------------------------------------
> 
> Key: XALANJ-2600
> URL: https://issues.apache.org/jira/browse/XALANJ-2600
> Project: XalanJ2
> Issue Type: Bug
> Security Level: No security risk; visible to anyone(Ordinary problems in Xalan \
>                 projects.  Anybody can view the issue.) 
> Components: Xalan
> Affects Versions: 2.7.2
> Reporter: Samuel Brezáni
> Assignee: Steven J. Hathaway
> Attachments: TransformerIdentityImpl.java.patch, xalan_memory_leak.jpg
> 
> 
> Hi.
> I found a serious memory leak in the Xalan library. It is caused by the \
> org.apache.xalan.transformer.TransformerIdentityImpl class. I try to explain \
> mechanism how the memory leak is caused: Web application is deployed on SAP \
> NetWeaver AS with Java 1.6 (1.6.0_95). The application uses Spring WS library but \
> also another libraries with dependency to Xalan library. When the web service is \
> invoked, then the TransformerIdentityImpl class is used. This class is used because \
> it's extends javax.xml.transform.Transformer and it is created by Java core method \
> - javax.xml.transform.TransformerFactory.newInstance(). A class \
> com.sun.xml.internal.messaging.saaj.soap.EnvelopeFactory is used for handling web \
> services. This object also contains cache (ParserPool) with SAXParser objects \
> (com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl). As key for this cache is \
> used an application class loader. EnvelopeFactory object and SAXParserImpl objects \
> are loaded by a system class loader, but TransformerIdentityImpl class is loaded by \
> an application class loader. During handling of web service a method \
> org.apache.xalan.transformer.TransformerIdentityImpl.transform(Source, Result) is \
> invoked. This method uses SAXParser as a reader. *Problem is that this method \
> register self for handling properties (eg: \
> "http://xml.org/sax/handlers/DeclHandler") but after processing method doesn't \
> unregister self from SAXParser*. It means that objects loaded by the system class \
> loaded has dependencies on objects loaded by the application class loader. Objects \
> are still loaded after application is undeployed because cached SAXParser \
> references TransformerIdentityImpl. I prepared very simple patch to fix this \
> problem. In the attachment is also picture which demonstrates situation.



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