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https://issues.apache.org/jira/browse/KAFKA-9712?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17058191#comment-17058191
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Nigel Liang edited comment on KAFKA-9712 at 3/12/20, 7:16 PM:
--------------------------------------------------------------
I have concluded more testing. My conclusion is that any file on the plugin
path that is either:
# not a jar, or
# a jar containing no classes
will trigger the bug. Consequence is that connect worker will not be able to
start up.
Possible workarounds include but are not limited to: * Revert back to v0.9.11
* Switch to reflections8 fork similar to what is done here -
[https://github.com/JanusGraph/janusgraph/pull/2029]
* Try to catch and handle the exception by skipping the problematic file and
continuing the scan
was (Author: nigel.liang):
I have concluded more testing. My conclusion is that any file on the plugin
path that is either: # not a jar, or
# a jar containing no classes
will trigger the bug. Consequence is that connect worker will not be able to
start up.
Possible workarounds include but are not limited to: * Revert back to v0.9.11
* Switch to reflections8 fork similar to what is done here -
[https://github.com/JanusGraph/janusgraph/pull/2029]
* Try to catch and handle the exception by skipping the problematic file and
continuing the scan
> Reflections library 0.9.12 introduced in 2.5 causes regression scanning for
> plugins on plugin_path
> --------------------------------------------------------------------------------------------------
>
> Key: KAFKA-9712
> URL: https://issues.apache.org/jira/browse/KAFKA-9712
> Project: Kafka
> Issue Type: Bug
> Affects Versions: 2.5.0
> Reporter: Nigel Liang
> Priority: Major
>
> Reflections v0.9.12 was introduced in 2.5 branch to remove Guava dependency -
> https://issues.apache.org/jira/browse/KAFKA-3061
> This version, however, contains a
> [bug|https://github.com/ronmamo/reflections/issues/273] that will cause
> regression when scanning for plugins if the `plugins_path` specified does not
> contain valid plugins. The case where we were able to repro this, the
> `plugins_path` was misconfigured to point to `~/.ssh` which contained
> unrelated files but no plugins. Further testing is needed to figure out if it
> will repro for other cases such as empty directory, combination of valid and
> invalid plugins in directory, just some types of plugins and not others in
> directory, etc.
> {code}
> [2020-03-12 18:07:01,045] INFO Loading plugin from: /home/ducker/.ssh
> (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
> [2020-03-12 18:07:01,047] DEBUG Loading plugin urls: []
> (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
> [2020-03-12 18:07:01,062] ERROR Stopping due to error
> (org.apache.kafka.connect.cli.ConnectDistributed)
> org.reflections.ReflectionsException: Scanner SubTypesScanner was not
> configured
> at org.reflections.Store.get(Store.java:39)
> at org.reflections.Store.get(Store.java:61)
> at org.reflections.Store.get(Store.java:46)
> at org.reflections.Store.getAll(Store.java:93)
> at org.reflections.Reflections.getSubTypesOf(Reflections.java:404)
> at
> org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader.getPluginDesc(DelegatingClassLoader.java:342)
> at
> org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader.scanPluginPath(DelegatingClassLoader.java:327)
> at
> org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader.scanUrlsAndAddPlugins(DelegatingClassLoader.java:260)
> at
> org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader.registerPlugin(DelegatingClassLoader.java:252)
> at
> org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader.initPluginLoader(DelegatingClassLoader.java:221)
> at
> org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader.initLoaders(DelegatingClassLoader.java:198)
> at
> org.apache.kafka.connect.runtime.isolation.Plugins.<init>(Plugins.java:60)
> at
> org.apache.kafka.connect.cli.ConnectDistributed.startConnect(ConnectDistributed.java:91)
> at
> org.apache.kafka.connect.cli.ConnectDistributed.main(ConnectDistributed.java:78)
> {code}
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