Different log files for multiple threads using log4j2

Question

I am running a Java application in which I am invoking multiple threads, each with some unique names. Now I want to create multiple log files for each of them and the name o

Answer 1

This can be done with the RoutingAppender. The FAQ page has a good example config.

Answer 2

I agree a RoutingAppender is the way to go. I initially used the routing appender in conjunction with the ${ctx:threadName} lookup where the 'ctx' uses the ThreadContext. I found that I would have to sprinkle in the code a line like this:

ThreadContext.put("threadName", Thread.currentThread().getName());

While that code works it's not extensible in the design of the code. If I were to add a new java.lang.Runnable to the code base, I would have to also include that line.

Rather, the solution seems to be to implement the 'org.apache.logging.log4j.core.lookup.StrLookup' and register the @Plugin with the PluginManager Like this:

Class: ThreadLookup

package my.logging.package    
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.lookup.StrLookup;

@Plugin(name = "thread", category = StrLookup.CATEGORY)
public class ThreadLookup implements StrLookup {

@Override
public String lookup(String key) {
    return Thread.currentThread().getName();
}

@Override
public String lookup(LogEvent event, String key) {
    return event.getThreadName() == null ? Thread.currentThread().getName()
            : event.getThreadName();
}

}    

Configuration: log4j2.xml (packages attribute of the Configuration registers the @Plugin with the PluginManager)

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="warn" packages="my.logging.package">
    <Appenders>
        <Routing name="Routing">
            <Routes pattern="$${thread:threadName}">
                <Route>
                    <RollingFile name="logFile-${thread:threadName}"
                    fileName="logs/concurrent-${thread:threadName}.log" filePattern="logs/concurrent-${thread:threadName}-%d{MM-dd-yyyy}-%i.log">
                    <PatternLayout pattern="%d %-5p [%t] %C{2} - %m%n" />
                    <Policies>
                        <SizeBasedTriggeringPolicy size="50 MB" />
                    </Policies>
                    <DefaultRolloverStrategy max="100" />
                </RollingFile>
            </Route>
        </Routes>
    </Routing>
    <Async name="async" bufferSize="1000" includeLocation="true">
        <AppenderRef ref="Routing" />
    </Async>
</Appenders>
<Loggers>
    <Root level="info">
        <AppenderRef ref="async" />
    </Root>
</Loggers>