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https://issues.apache.org/jira/browse/FLINK-5690?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15865794#comment-15865794
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ASF GitHub Bot commented on FLINK-5690:
---------------------------------------
Github user alpinegizmo commented on a diff in the pull request:
https://github.com/apache/flink/pull/3300#discussion_r101038332
--- Diff: docs/dev/best_practices.md ---
@@ -310,3 +310,17 @@ Next, you need to put the following jar files into the
`lib/` folder:
Note that you need to explicitly set the `lib/` directory when using a per
job YARN cluster.
The command to submit Flink on YARN with a custom logger is: `./bin/flink
run -yt $FLINK_HOME/lib <... remaining arguments ...>`
+
+
+## Resolving Dependency Conflicts with Flink using the maven-shade-plugin.
+
+Apache Flink loads many classes by default into its classpath (the
[classloading is described here in
detail]({{site.baseurl}}/monitoring/debugging_classloading.html)). If a user
uses a different version of a library that Flink is using, often
`IllegalAccessExceptions` or `NoSuchMethodError` are the result.
+
+Through Hadoop, Flink for example depends on the `aws-sdk` library or on
`protobuf-java`. If your user code is using these libraries and you run into
issues we recommend relocating the dependency in your user code jar.
+
+Apache Maven offers the
[maven-shade-plugin](https://maven.apache.org/plugins/maven-shade-plugin/),
that allows to change the package of a class *after* compiling it (so the code
you are writing is not affected by the shading). For example if you have the
`com.amazonaws` packages from the aws sdk in your user code jar, the shade
plugin would relocate them into the `org.myorg.shaded.com.amazonaws` package,
so that your code is calling your aws sdk version.
--- End diff --
I suggest a minor rewording:
Apache Maven offers the
[maven-shade-plugin](https://maven.apache.org/plugins/maven-shade-plugin/),
which allows one to change the package of a class *after* compiling it ...
> protobuf is not shaded properly
> -------------------------------
>
> Key: FLINK-5690
> URL: https://issues.apache.org/jira/browse/FLINK-5690
> Project: Flink
> Issue Type: Bug
> Components: Build System
> Affects Versions: 1.1.4, 1.3.0
> Reporter: Andrey
> Assignee: Robert Metzger
>
> Currently distributive contains com/google/protobuf package. Without proper
> shading client code could fail with:
> {code}
> Caused by: java.lang.IllegalAccessError: tried to access method
> com.google.protobuf.XXXX
> {code}
> Steps to reproduce:
> * create job class "com.google.protobuf.TestClass"
> * call com.google.protobuf.TextFormat.escapeText(String) method from this
> class
> * deploy job to flink cluster (usign web console for example)
> * run job. In logs IllegalAccessError.
> Issue in package protected method and different classloaders. TestClass
> loaded by FlinkUserCodeClassLoader, but TextFormat class loaded by
> sun.misc.Launcher$AppClassLoader
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