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https://issues.apache.org/jira/browse/MNG-7161?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17351778#comment-17351778
]
Guy Brand commented on MNG-7161:
--------------------------------
[~michael-o] We use it for the included {{Prompter}} but we'll now remove this
dependency and do it by our own to fix this for the current extension. But we'd
like that all our old extensions still work with Maven 4.0.0 and this error
would not make it possible.
This error can always occur when a plugin or extension holds a reference to the
system output streams and then does it's own disposal or similar before JAnsi
uninstalls itself.
[~mthmulders] Thanks for adding another example.
> Error thrown during uninstalling of JAnsi
> -----------------------------------------
>
> Key: MNG-7161
> URL: https://issues.apache.org/jira/browse/MNG-7161
> Project: Maven
> Issue Type: Bug
> Affects Versions: 4.0.x-candidate, 4.0.0, 4.0.0-alpha-1
> Reporter: Guy Brand
> Priority: Critical
>
> Our integration tests stopped working after we started to test with a Maven
> {{4.0.0-alpha-1}} nightly which included this commit:
> [https://github.com/apache/maven/commit/195fb626a9a4e5a0774f779b6d8da1cb9ef38468#diff-9c5fb3d1b7e3b0f54bc5c4182965c4fe1f9023d449017cece3005d3f90e8e4d8R310-R317]
> In this commit the {{maven-shared-utils}} and the {{jansi}} dependencies are
> being upgraded. When we then run our integration tests we get the following
> null pointer exception:
> {code:java}
> java.lang.NullPointerException
> at org.fusesource.jansi.AnsiPrintStream.uninstall(AnsiPrintStream.java:79)
> at org.fusesource.jansi.AnsiConsole.systemUninstall(AnsiConsole.java:524)
> at
> org.apache.maven.shared.utils.logging.MessageUtils.doSystemUninstall(MessageUtils.java:101)
> at
> org.apache.maven.shared.utils.logging.MessageUtils.systemUninstall(MessageUtils.java:80)
> at org.apache.maven.cli.MavenCli.main(MavenCli.java:203)
> at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native
> Method)
> at
> java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
> at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.base/java.lang.reflect.Method.invoke(Method.java:566)
> at
> org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:282)
> at
> org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:225)
> at
> org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:406)
> at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:347)
> {code}
>
> We debugged this and [these
> changes|https://github.com/fusesource/jansi/commit/63bd892b2bdfc253ec119a57bdd42df5e80fd859#diff-d59db8655d9ae2d11948e2b411c34fc9e8513f29065d82c978d7128dafbe3bafR414-R420]
> in JAnsi introduced in the above upgraded version, is the source of the
> exception. The NPE is caused because the {{out}} reference is {{null}} at the
> time it wants to uninstall the {{AnsiOutputStream}}. This reference is nulled
> because we use the Plexus interactivity library which [disposes the
> {{DefaultOutputHandler}}|https://github.com/codehaus-plexus/plexus-interactivity/blob/master/plexus-interactivity-api/src/main/java/org/codehaus/plexus/components/interactivity/DefaultOutputHandler.java#L51-L54]
> on the tear down of Plexus, in which the {{System.out}} reference will be
> closed which is in fact the {{out}} reference of the {{AnsiConsole}} JAnsi
> will be [initialized
> before|https://github.com/apache/maven/blob/3e917677e484067b853eaa4a6de44ebcf5a988de/maven-embedder/src/main/java/org/apache/maven/cli/MavenCli.java#L200]
> the Plexus container). This happens
> [here|https://github.com/apache/maven/blob/3e917677e484067b853eaa4a6de44ebcf5a988de/maven-embedder/src/main/java/org/apache/maven/cli/MavenCli.java#L202],
> so before JAnsi will be uninstalled in
> [here|https://github.com/apache/maven/blob/3e917677e484067b853eaa4a6de44ebcf5a988de/maven-embedder/src/main/java/org/apache/maven/cli/MavenCli.java#L203].
> There are two options to solve this:
> 1. Report this to JAnsi such that they catch this valid use case and do not
> throw as this worked without any exceptions in older versions.
> 2. Fix the {{MessageUtils#doSystemUninstall()}} and catch all exceptions and
> swallow them, as if it can't uninstall it, then Maven itself is not capable
> of fixing this state either. This is already done in a similar way
> [here|https://github.com/apache/maven-shared-utils/blob/17091d82508deb9b7067f3434ba16f660ffc5023/src/main/java/org/apache/maven/shared/utils/logging/MessageUtils.java#L85-L92]
> for removing the shutdown hook.
> Our proposal is to do #2 which would make Maven itself resilient to such use
> cases as there are other extensions/plugin out there which also retrieve a
> reference for the system output streams and therefore they would fail with
> Maven 4.0.0. This would also make this part future proof, as when there are
> other errors thrown during the uninstall, Maven itself does not break.
> We can as well report this to JAnsi too such that this gets fixed there as
> well.
>
> What are your opinions on that?
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