Ewen Cheslack-Postava created KAFKA-5229:
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Summary: Reflections logs excessive warnings when scanning
classpaths
Key: KAFKA-5229
URL: https://issues.apache.org/jira/browse/KAFKA-5229
Project: Kafka
Issue Type: Bug
Components: KafkaConnect
Affects Versions: 0.10.2.1, 0.10.2.0, 0.10.1.1, 0.10.1.0, 0.10.0.1, 0.10.0.0
Reporter: Ewen Cheslack-Postava
Priority: Minor
We use Reflections to scan the classpath for available plugins (connectors,
converters, transformations), but when doing so Reflections tends to generate a
lot of log noise like this:
{code}
[2017-05-12 14:59:48,224] WARN could not get type for name
org.jboss.netty.channel.SimpleChannelHandler from any class loader
(org.reflections.Reflections:396)
org.reflections.ReflectionsException: could not get type for name
org.jboss.netty.channel.SimpleChannelHandler
at org.reflections.ReflectionUtils.forName(ReflectionUtils.java:390)
at org.reflections.Reflections.expandSuperTypes(Reflections.java:381)
at org.reflections.Reflections.<init>(Reflections.java:126)
at
org.apache.kafka.connect.runtime.PluginDiscovery.scanClasspathForPlugins(PluginDiscovery.java:68)
at
org.apache.kafka.connect.runtime.AbstractHerder$1.run(AbstractHerder.java:391)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ClassNotFoundException:
org.jboss.netty.channel.SimpleChannelHandler
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
at org.reflections.ReflectionUtils.forName(ReflectionUtils.java:388)
... 5 more
{code}
Despite being benign, these warnings worry users, especially first time users.
We should either a) see if we can get Reflections to turn off these specific
warnings via some config or b) make Reflections only log at > WARN by default
in our log4j config. (b) is probably safe since we should only be seeing these
at startup and I don't think I've seen any actual issue logged at WARN.
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