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https://issues.apache.org/jira/browse/HADOOP-16174?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16787981#comment-16787981
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Steve Loughran commented on HADOOP-16174:
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bq. We do not want to preserve the ref outside of the switch case. Using a hard
ref to the logger keeps the object in memory while we reach SSL.java:196 which
is enough for us
I am not convinced the compiler will bother retaining a reference for the
duration of the switch, given there is only one reference in the limited stop.
I'm happy to be wrong, but even if I am, the javac team retains the right to
optimise things like that away. And you are at risk of someone editing the
code in future, as the reasoning here is not obvious
Reinstating the log to info afterwards will guarantee that the reference is
retained, and stop anyone cleaning up the code from unintentionally removing
the reference. Add a comment to the clause to explain the problem too. thanks
> Disable wildfly logs to the console
> -----------------------------------
>
> Key: HADOOP-16174
> URL: https://issues.apache.org/jira/browse/HADOOP-16174
> Project: Hadoop Common
> Issue Type: Bug
> Components: fs/azure
> Reporter: Denes Gerencser
> Priority: Major
> Attachments: HADOOP-16174-001.patch
>
>
> We experience that the wildfly log
> {code:java}
> Mar 06, 2019 4:33:53 PM org.wildfly.openssl.SSL init
> INFO: WFOPENSSL0002 OpenSSL Version OpenSSL 1.0.2g 1 Mar 2016
> {code}
> (sometimes) appears on the console but it should never. Note: this is a
> consequence of HADOOP-15851.
> Our analysis shows the reason is that
> {code:java}
> java.util.logging.Logger.getLogger()
> {code}
> is not guaranteed to always return the _same_ logger instance so
> SSLSocketFactoryEx may set log level on different logger object than the one
> used by wildfly-openssl
> ([https://github.com/wildfly/wildfly-openssl/blob/ace72ba07d0c746b6eb46635f4a8b122846c47c8/java/src/main/java/org/wildfly/openssl/SSL.java#L196)].
> From javadoc of java.util.logging.Logger.getLogger:
> 'Note: The LogManager may only retain a weak reference to the newly created
> Logger. It is important to understand that a previously created Logger with
> the given name may be garbage collected at any time if there is no strong
> reference to the Logger. In particular, this means that two back-to-back
> calls like{{getLogger("MyLogger").log(...)}} may use different Logger objects
> named "MyLogger" if there is no strong reference to the Logger named
> "MyLogger" elsewhere in the program.'
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