I log classes when loaded into a separate log file.
I am sure classes are loaded from expected jar files
The files are 4 times because I have four web applications in the system.
$ grep javax.activation.DataContentHandler classloaded.log
[5436.540s][info][class,load] javax.activation.DataContentHandler source:
file:/<tomcatPath>/webapps/app1/WEB-INF/lib/activation-1.1.jar
[8903.600s][info][class,load] javax.activation.DataContentHandler source:
file:/<tomcatPath>/webapps/app2/WEB-INF/lib/activation-1.1.jar
[36283.268s][info][class,load] javax.activation.DataContentHandler source:
file:/<tomcatPath>/webapps/app3/WEB-INF/lib/activation-1.1.jar
[558992.846s][info][class,load] javax.activation.DataContentHandler source:
file:/mnt/app/tomcat/webapps/app4/WEB-INF/lib/activation-1.1.jar
(0)
$ grep com.sun.mail.handlers.text_html classloaded.log
[5436.558s][info][class,load] com.sun.mail.handlers.text_html source:
file:/<tomcatPath>/webapps/app1/WEB-INF/lib/javax.mail-1.6.2.jar
[8903.600s][info][class,load] com.sun.mail.handlers.text_html source:
file:/<tomcatPath>/webapps/app2/WEB-INF/lib/javax.mail-1.6.2.jar
[36283.283s][info][class,load] com.sun.mail.handlers.text_html source:
file:/<tomcatPath>/webapps/app3/WEB-INF/lib/javax.mail-1.6.2.jar
[558992.864s][info][class,load] com.sun.mail.handlers.text_html source:
file:/<tomcatPath>/webapps/app4/WEB-INF/lib/javax.mail-1.6.2.jar
Regards,
Zdenek Henek
On Wed, May 21, 2025 at 12:44 PM Zdeněk Henek <vrab...@gmail.com> wrote:
> Hello,
>
> I am getting these errors in one of our systems:
>
> java.lang.ClassCastException: class com.sun.mail.handlers.text_html cannot
> be cast to class javax.activation.DataContentHandler
> (com.sun.mail.handlers.text_html is in unnamed module of loader
> org.apache.catalina.loader.ParallelWebappClassLoader @6c5398e5;
> javax.activation.DataContentHandler is in unnamed module of loader
> org.apache.catalina.loader.ParallelWebappClassLoader @719f9efd)
> at
> javax.activation.MailcapCommandMap.getDataContentHandler(MailcapCommandMap.java:596)
> at
> javax.activation.MailcapCommandMap.createDataContentHandler(MailcapCommandMap.java:550)
> at
> javax.activation.DataHandler.getDataContentHandler(DataHandler.java:611)
> at javax.activation.DataHandler.writeTo(DataHandler.java:315)
> at
> javax.mail.internet.MimeUtility.getEncoding(MimeUtility.java:340)
> at
> javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1575)
> at
> javax.mail.internet.MimeMessage.updateHeaders(MimeMessage.java:2271)
> at
> javax.mail.internet.MimeMessage.saveChanges(MimeMessage.java:2231)
> at javax.mail.Transport.send(Transport.java:123)
>
>
> The system runs on Apache Tomcat 9.0.102, OpenJDK Runtime Environment
> Temurin-21.0.6+7 (build 21.0.6+7-LTS), RHEL 9.5 Linux
>
> The functionality has a number of threads in the thread pool and only one
> of the threads is causing this issue. Other threads are working as expected.
>
> I am aware of duplicated jar files (even the same jar file version) in
> different classloaders or even in the same classloader. I understand the
> classes could be in jars with different names. I have tool to review all
> jar files and report
> jar files having the same classes.
>
> Classloaders are configured this way:
>
> current Tomcat classloaders configuration conf/catalina.properties
>
>
> common.loader="${catalina.base}/lib","${catalina.base}/lib/.jar","${catalina.home}/lib","${catalina.home}/lib/.jar"
>
> server an shared loaders are empty
> server.loader=
> shared.loader=
>
> The class com.sun.mail.handlers.text_html is in jar file with name
> javax.mail-1.6.2.jar and the javax.activation.DataContentHandler
> activation-1.1.jar
> Both jars are in webapplication in WEB-INF/lib directory
> There is multiple web applications with these jar files, but these jar
> files are not in <Tomcat>/lib directory
>
> The jars are in same war application but in the exception they are in
> different ParallelWebappClassLoaders
> ParallelWebappClassLoader @6c5398e5 and ParallelWebappClassLoader @719f9efd
>
> I have run a heap dump of the application and listed all
> org.apache.catalina.loader.ParallelWebappClassLoader instances.
> There are 8 objects but none has object id 6c5398e5 or 719f9efd . I tried
> to search objects using these object ids in MAT, but they are not available
> even when I keep unreachable objects. The object ids are the same every
> time in the exceptions.
>
> I don't see any errors in catalina.out or in localhost<timestamp>.log
> files, and the above is the only error I get. System runs stable. We don't
> use hot redeployment in this server.
>
> The system CLASSPATH variable is not pointing to any jar files.
>
> Any idea what is going on here? Why does this happen?
> The system with the error is still running. I could collect more
> information if needed.
>
> Thank you.
>
> Regards,
> Zdenek Henek
>
