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https://issues.apache.org/jira/browse/LOG4J2-3407?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17494576#comment-17494576
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Kenny MacLeod commented on LOG4J2-3407:
---------------------------------------
Normally, I'd 100% agree with you, but the point of the log4j 1.2 compat layer
is to match the legacy behaviour as much as is practical, and this is what the
legacy behaviour is.
> PropertiesConfiguration.parseAppender NPE when logger refers to non-existent
> appender
> -------------------------------------------------------------------------------------
>
> Key: LOG4J2-3407
> URL: https://issues.apache.org/jira/browse/LOG4J2-3407
> Project: Log4j 2
> Issue Type: Bug
> Components: Log4j 1.2 bridge
> Affects Versions: 2.17.1
> Reporter: Kenny MacLeod
> Priority: Minor
> Attachments: LOG4J2-3407.patch
>
>
> When parsing a {{log4j.proprties}} file that contains a logger that refers to
> a non-existent appender, you get a NPE.
> While this is clearly a malformed configuration, Log4j 1.2.x silently ignored
> this, and the log4j2 bridge should be as tolerant.
> Note that {{PropertiesConfiguration#parseLogger}} is already tolerant of the
> appender being missing (it does a null check on the result of
> {{{}parseAppender{}}}), but {{parseAppender}} itself is not tolerant.
> An example config would be:
> {noformat}
> log4j.logger.mylogger=INFO, myappender
> # log4j.appender.myappender=org.apache.log4j.ConsoleAppender
> {noformat}
> The appender has been commented out, to illustrate the bug.
> Stack trace from log4j 2.17.1:
> {noformat}
> Caused by: java.lang.NullPointerException
> at
> org.apache.log4j.builders.BuilderManager.parseAppender(BuilderManager.java:72)
> at
> org.apache.log4j.config.PropertiesConfiguration.parseAppender(PropertiesConfiguration.java:428)
> at
> org.apache.log4j.config.PropertiesConfiguration.parseLogger(PropertiesConfiguration.java:406)
> at
> org.apache.log4j.config.PropertiesConfiguration.parseLoggers(PropertiesConfiguration.java:351)
> at
> org.apache.log4j.config.PropertiesConfiguration.doConfigure(PropertiesConfiguration.java:304)
> at
> org.apache.log4j.config.PropertiesConfiguration.doConfigure(PropertiesConfiguration.java:93)
> at
> org.apache.log4j.config.Log4j1Configuration.initialize(Log4j1Configuration.java:60)
> at
> org.apache.logging.log4j.core.config.AbstractConfiguration.start(AbstractConfiguration.java:293)
> at
> org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:626)
> at
> org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:699)
> at
> org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:716)
> at
> org.apache.logging.log4j.core.LoggerContext.start(LoggerContext.java:270)
> at
> org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:155)
> at
> org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:47)
> at
> org.apache.logging.log4j.LogManager.getContext(LogManager.java:196)
> at
> org.apache.logging.log4j.spi.AbstractLoggerAdapter.getContext(AbstractLoggerAdapter.java:137)
> at
> org.apache.logging.slf4j.Log4jLoggerFactory.getContext(Log4jLoggerFactory.java:55)
> at
> org.apache.logging.log4j.spi.AbstractLoggerAdapter.getLogger(AbstractLoggerAdapter.java:47)
> at
> org.apache.logging.slf4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:33)
> at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:363)
> at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:388)
> {noformat}
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