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https://issues.apache.org/jira/browse/BEAM-308?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15300778#comment-15300778
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ASF GitHub Bot commented on BEAM-308:
-------------------------------------
Github user asfgit closed the pull request at:
https://github.com/apache/incubator-beam/pull/390
> PipelineOptions throws when using package-private PipelineOptions interfaces
> from multiple packages
> ---------------------------------------------------------------------------------------------------
>
> Key: BEAM-308
> URL: https://issues.apache.org/jira/browse/BEAM-308
> Project: Beam
> Issue Type: Bug
> Components: sdk-java-core
> Reporter: Scott Wegner
> Assignee: Scott Wegner
> Priority: Minor
>
> If a PipelineOptions instance is used as multiple PipelineOptions
> package-private interfaces from different packages, {{PipelineOptions.as}}
> will throw an exception:
> {quote}
> java.lang.IllegalArgumentException: non-public interfaces from different
> packages
> at java.lang.reflect.Proxy$ProxyClassFactory.apply(Proxy.java:652)
> at java.lang.reflect.Proxy$ProxyClassFactory.apply(Proxy.java:592)
> at java.lang.reflect.WeakCache$Factory.get(WeakCache.java:244)
> at java.lang.reflect.WeakCache.get(WeakCache.java:141)
> at java.lang.reflect.Proxy.getProxyClass0(Proxy.java:455)
> at java.lang.reflect.Proxy.getProxyClass(Proxy.java:405)
> at
> org.apache.beam.sdk.options.PipelineOptionsFactory.validateWellFormed(PipelineOptionsFactory.java:620)
> at
> org.apache.beam.sdk.options.ProxyInvocationHandler.as(ProxyInvocationHandler.java:209)
> at
> org.apache.beam.sdk.options.ProxyInvocationHandler.invoke(ProxyInvocationHandler.java:135)
> at com.sun.proxy.$Proxy6.as(Unknown Source)
> {quote}
> This fails because ProxyInvocationHandler attempts to create a Java Proxy
> object implementing the full set of interfaces, which has the
> [restriction|https://docs.oracle.com/javase/7/docs/api/java/lang/reflect/Proxy.html#getProxyClass(java.lang.ClassLoader,%20java.lang.Class...)]:
>
> bq. All non-public interfaces must be in the same package; otherwise, it
> would not be possible for the proxy class to implement all of the interfaces,
> regardless of what package it is defined in.
> This can be triggered in a couple edge-case scenarios:
> # {{PipelineOptions.as}} is called on the same PipelineOptions instance with
> multiple package-private interfaces.
> # {{PipelineOptionsFactory.register}} is called with a package-private
> interface, and then {{PipelineOptions.as}} is called with a different
> package-private instance.
> We hit the second scenario in [DataflowSDK unit
> tests|https://github.com/GoogleCloudPlatform/DataflowJavaSDK/pull/286#issuecomment-221438063].
> It's hard to trigger, but possible.
> ----
> I propose we make the behavior for package-private options explicit:
> # Give a better exception message if we hit this issue in
> {{PipelineOptions.as}} listing the non-public interfaces and what packages
> they're in.
> # Explicitly reject non-public interfaces from
> {{PipelineOptionsFactory.register}}, since this state is global and is easier
> to cause issues.
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