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From: StephanEwen <git@git.apache.org>
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Subject: [GitHub] flink pull request #4891: [FLINK-7669] Always load Flink classes via parent ...
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Message-Id: <20171023173242.A3E18DFBC6@git1-us-west.apache.org>
Date: Mon, 23 Oct 2017 17:32:42 +0000 (UTC)
archived-at: Mon, 23 Oct 2017 17:32:50 -0000

Github user StephanEwen commented on a diff in the pull request:

    https://github.com/apache/flink/pull/4891#discussion_r146338877
  
    --- Diff: docs/monitoring/debugging_classloading.md ---
    @@ -57,22 +57,34 @@ YARN classloading differs between single job deployments and sessions:
     
     **Mesos**
     
    -Mesos setups following [this documentation](../ops/deployment/mesos.html) currently behave very much like the a 
    +Mesos setups following [this documentation](../ops/deployment/mesos.html) currently behave very much like the a
     YARN session: The TaskManager and JobManager processes are started with the Flink framework classes in classpath, job
     classes are loaded dynamically when the jobs are submitted.
     
    +## Configuring ClassLoader Resolution Order
    +
    +Flink uses a hierarchy of ClassLoaders for loading classes from the user-code jar(s). The user-code
    +ClassLoader has a reference to the parent ClassLoader, which is the default Java ClassLoader in most
    +cases. By default, Java ClassLoaders will first look for classes in the parent ClassLoader and then in
    +the child ClassLoader for cases where we have a hierarchy of ClassLoaders. This is problematic if you
    +have in your user jar a version of a library that conflicts with a version that comes with Flink. You can
    +change this behaviour by configuring the ClassLoader resolution order via
    +`classloader.resolve-order: child-first` in the Flink config. However, Flink classes will still
    +be resolved through the parent ClassLoader first, altough you can also configure this via
    +`classloader.always-parent-first-patterns`, which is `org.apache.flink`, by default.
    --- End diff --
    
    change `always-parent-first-patterns` to `parent-first-patterns`?


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