[LOG4J2-3295] Reconfiguration failure with an error

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Won't Fix
• Affects Version/s: 2.17.0
• Component/s: Configuration, Configurators
• Assignee: Unassigned
• Reporter: Mike Li
• Created: 29/Dec/21 01:52
• Updated: 05/Jan/22 16:33
• Resolved: 30/Dec/21 04:58

Description

Steps to recreate:

1. start with log4j2.xml with following content:

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="DEBUG" monitorInterval="30">

 

    <Appenders>
    <File name="FILE" fileName="c:\temp\product.log">
        <PatternLayout>
            <Pattern>ProductName:%-10p %d{yyyy-MM-dd HH:mm:ss.SSS}

{GMT} context:%x [%t] - %-50m - %M(%F:%L)%n</Pattern>
        </PatternLayout>
        
    </File>

    </Appenders>
    <Loggers>
        <Root level="INFO">
            <AppenderRef ref="FILE"/>
        </Root>
    </Loggers>
</Configuration>

 

2. After the application is started and running, edit the log4j2.xml file with the following content, notice that the fileName in the WRAP appender is the same as that in the original FILE appender.

 

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="DEBUG" monitorInterval="30" >


    <Appenders>
    <Async name="ASYNC" includeLocation="true" bufferSize="4096">
        <AppenderRef ref="WRAP"/>
    </Async>

    <RollingFile name="WRAP" fileName="c:\temp\product.log" filePattern="c:\temp\product.log.%i">
        <PatternLayout pattern="ProductName:%-7p %d{yyyy-MM-dd HH:mm:ss.SSS}{GMT}

context:%x [%t] - %-50m - %M(%F:%L)%n"/>
        <Policies>
            <SizeBasedTriggeringPolicy size="1048576"/>
        </Policies>
        <DefaultRolloverStrategy max="4"/>
    </RollingFile>

    </Appenders>
    <Loggers>
        <Root level="DEBUG">
            <AppenderRef ref="ASYNC"/>
        </Root>
    </Loggers>
</Configuration>

 

3. Wait for the log4j to detect the change in 30 seconds to reconfigure. When the reconfigure starts, it reports an error. Here is the exception stack:

 

2021-12-28 17:42:41,688 Log4j2-TF-1-ConfiguratonFileWatcher-4 ERROR Could not create plugin of type class org.apache.logging.log4j.core.appender.RollingFileAppender for element RollingFile org.apache.logging.log4j.core.config.ConfigurationException: Configuration has multiple incompatible Appenders pointing to the same resource 'c:\temp\product.log'
    at org.apache.logging.log4j.core.appender.AbstractManager.narrow(AbstractManager.java:169)
    at org.apache.logging.log4j.core.appender.rolling.RollingFileManager.getFileManager(RollingFileManager.java:217)
    at org.apache.logging.log4j.core.appender.RollingFileAppender$Builder.build(RollingFileAppender.java:146)
    at org.apache.logging.log4j.core.appender.RollingFileAppender$Builder.build(RollingFileAppender.java:62)
    at org.apache.logging.log4j.core.config.plugins.util.PluginBuilder.build(PluginBuilder.java:122)
    at org.apache.logging.log4j.core.config.AbstractConfiguration.createPluginObject(AbstractConfiguration.java:1107)
    at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:1032)
    at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:1024)
    at org.apache.logging.log4j.core.config.AbstractConfiguration.doConfigure(AbstractConfiguration.java:643)
    at org.apache.logging.log4j.core.config.AbstractConfiguration.initialize(AbstractConfiguration.java:243)
    at org.apache.logging.log4j.core.config.AbstractConfiguration.start(AbstractConfiguration.java:289)
    at org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:626)
    at org.apache.logging.log4j.core.LoggerContext.onChange(LoggerContext.java:762)
    at org.apache.logging.log4j.core.util.AbstractWatcher$ReconfigurationRunnable.run(AbstractWatcher.java:93)
    at java.base/java.lang.Thread.run(Thread.java:831)