Hello Gemini Web devs,
We are using Gemini Web with Equinox and we had to update our test setup
recently to reload a web application, while Tomcat is running. We ended up
using Tomcat JMX for that, but it turned out a NPE is thrown when the web
application is re-started. The issue is reproducible with any web
application bundle. To reproduce it with latest Gemini Web 2.2.2 and the
"simple-war.war" web application, follow these steps:
1. Install the war in Equinox:
osgi> install file:simple-war.war
2. Run jconsole JDK tool and connect to the Equinox process
3. Open the "//localhost/simple-war" node under "Catalina/WebModule",
navigate to the operations and execute "reload"
4. Observe the following exception appears in Equinox console:
org.apache.catalina.core.StandardContext reload
SEVERE: Exception starting Context with name [/simple-war]
org.apache.catalina.LifecycleException: Failed to start component
[StandardEngine[Catalina].StandardHost[localhost].StandardContext[/simple-war]]
at
org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
at
org.apache.catalina.core.StandardContext.reload(StandardContext.java:3926)
...
Caused by: org.apache.catalina.LifecycleException: Failed to start
component
[org.eclipse.gemini.web.tomcat.internal.loading.BundleWebappLoader@6638e53]
...
Caused by: java.lang.NullPointerException
at
org.eclipse.gemini.web.tomcat.internal.loading.BundleClassPathURLExtractor.extractBundleClassPathURLs(BundleClassPathURLExtractor.java:37)
at
org.eclipse.gemini.web.tomcat.internal.loading.BundleWebappClassLoader.addBundleClassPathURLs(BundleWebappClassLoader.java:101)
at
org.eclipse.gemini.web.tomcat.internal.loading.BundleWebappClassLoader.<init>(BundleWebappClassLoader.java:77)
at
org.eclipse.gemini.web.tomcat.internal.loading.BundleWebappLoader.createClassLoader(BundleWebappLoader.java:88)
at
org.eclipse.gemini.web.tomcat.internal.loading.BundleWebappLoader.startInternal(BundleWebappLoader.java:169)
I checked the sources and it seems that the BundleWebappClassLoader nulls
out the "bundle" and "classLoaderCustomizer" fields upon stop:
http://git.eclipse.org/c/gemini.web/org.eclipse.gemini.web.gemini-web-container.git/tree/org.eclipse.gemini.web.tomcat/src/main/java/org/eclipse/gemini/web/tomcat/internal/loading/BundleWebappLoader.java#n212
These are initialized in the constructor and since a new
BundleWebappClassLoader instance is not created when starting the context
after a stop, these remain null and ultimately cause the exception.
It seems like the fix would be easy - removing the respective null
assigments so that the "bundle" and "classLoaderCustomizer" instances are
preserved. If there are no side effects and there is no specific reason for
this piece of code, I would open a defect and attach a patch, but first I
wanted to get your opinion on this. Does this sound reasonable?
Thanks,
Detelin
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