Hello,
I have a GWT 2.10.0 project compiled in Java 11, built with Maven 3.8.4
through the GWT-maven-plugin, and deployed to a WebLogic 14c server.
Recently I have seen errors related to the Tomcat JAR scanner and the
embedded server utilized in development mode. The application was working
but after the upgrade to version 2.10.0, errors fill the server out log in
WebLogic that the Tomcat StandardJarScanner failed to scan JAR files from
the classloader hierarchy along with a silent failure of the application
itself. After ensuring GWT was starting in Production Mode, I added the
following elements to the configuration section of the plugin to ensure the
server would not start up:
<noServer>true</noServer>
<compilerArgs>
<arg>-noincremental</arg>
</compilerArgs>
After recompiling with these changes the application was able to function
normally once again but the errors regarding the JAR scanner being unable
to scan from the classloader hierarchy remained. The JARs it attempted to
scan were ones that are not part of the application nor in any of the
dependency trees of the dependencies of the gwt-maven-plugin.
I want to disable that JAR scanning and the errors it produces when the
application is started. I attempted to do so by adding a context.xml to the
webapp/META-INF to the scanning with configuration to limit the scanner but
it did not seem to have an effect. Here are logs for the errors happening
in the out file for the WL server the application is deployed to:
Failed to scan <JarFile> from classloader hierarchy
Java.io.IOException: java.lang.reflect.InvocationTargetException
at
org.apache.tomcat.util.compat.Jre9Compat.jarFileNewInstance(Jre9Compat.java:209)
at org.apache.tomcat.util.scan.JarFileUrlJar.<init>(JarFileUrlJar.java:65)
at org.apache.tomcat.util.scan.JarFactory.newInstance(JarFactory.java:49)
at
org.apache.tomcat.util.scan.StandardJarScanner.process(StandardJarScanner.java:387)
at
org.apache.tomcat.util.scan.StandardJarScanner.processURLs(StandardJarScanner.java:322)
at
org.apache.tomcat.util.scan.StandardJarScanner.doScanClassPath(StandardJarScanner.java:284)
at
org.apache.tomcat.util.scan.StandardJarScanner.scan(StandardJarScanner.java:235)
at org.apache.jasper.servlet.TldScanner.scanJars(TldScanner.java:262)
at org.apache.jasper.servlet.TldScanner.scan(TldScanner.java:104)
at
org.apache.jasper.servlet.JasperInitializer.onStartup(JasperInitializer.java:101)
at
weblogic.servlet.internal.WebAppServletContext.initContainerInitializers(WebAppServletContext.java:1428)
...
Additionally, in the server log file there is this outputted on startup:
<warning: No org.apache.tomcat.JarScanner set in ServletContext. Falling
back to default JarScanner implementation.>
This link
(https://stackoverflow.com/questions/66689374/spring-boot-with-jetty-disable-o-a-tomcat-util-scan-standardjarscanner)
mentioned that the org.apache.tomcat.util.scan.StandardJarScanner can
originate from apache-jsp JARs which gwt-dev 2.10.0 has a dependency. I
confirmed this in my IDE and maven repository but I have been unable to
prevent the scanning of the classpath hierarchy for TLDs. Is there a way to
disable this scanning of TLDs and JAR files from the classloader hierarchy?
Help is very much appreciated!
Thank you,
Aynesh Patel
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