Simon,
On 3/18/24 15:17, Simon Niederberger wrote:
I'm analyzing a memory leak reported by Tomcat, and have narrowed it
down to org.apache.jasper.compiler.EncodingDetector:
private static final XMLInputFactory XML_INPUT_FACTORY;
static {
XML_INPUT_FACTORY = XMLInputFactory.newInstance();
}
This class is called by webapp code on a GET request
at
org.apache.jasper.compiler.EncodingDetector.<clinit>(EncodingDetector.java:38)
at
org.apache.jasper.compiler.ParserController.determineSyntaxAndEncoding(ParserController.java:324)
at
org.apache.jasper.compiler.ParserController.doParse(ParserController.java:201)
at
org.apache.jasper.compiler.ParserController.parseDirectives(ParserController.java:128)
at org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:207)
...
at
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:396)
at
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:380)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:328)
at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:658)
The EncodingDetector class, if not yet loaded, will be loaded in the
common classloader, then continue by loading the XMLInputFactory using
the webapp context, and might end up with a XMLInputFactory
implementation from a webapp-provided JAR. If that happens, the webapp
can't undeploy. (In my case, woodstox WstxInputFactory registers
itself as ServiceProvider for XMLInputFactory)
For completeness: javax.xml.stream.FactoryFinder.findServiceProvider()
is called without classloader (cl = null), and has
if (cl == null) {
//the current thread's context class loader
serviceLoader = ServiceLoader.load(type);
} else {
serviceLoader = ServiceLoader.load(type, cl);
}
I can't find anything online about memory leaks from webapp-provided
XMLInputFactory implementations, but this must be fairly common. Is my
understanding correct, or have I mis-configured something? (I'm mainly
wondering whether any XMLInputFactory-implementing JARs belong in
tomcat/lib, but again I'm not finding anything online confirming that)
Tomcat 10.1.19
JVM 17.0.10+7-Ubuntu-120.04.1
Ubuntu 20.04.6 LTS
I'm not sure how many web applications ship with an XMLInputSource, but
they definitely do exist. I'm fairly sure most applications won't set a
system property or ship with a stax.properties/jaxp.properties file to
override the default implementation, but of course if it's possible,
someone will eventually do it.
I'm curious: in your example, how are you declaring your implementation
class, and which implementation are you using?
Are you able to log in EncodingDetector.<clinit> what the value of the
thread's context classloader is? I would expect that it's using the
common classloader, as you say, and that the implementation class would
also be loaded using that same classloader.
-chris
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org
For additional commands, e-mail: users-h...@tomcat.apache.org