Display thread id instead thread name in log

Question

I have a Struts application with log4j to display information about application.

The pattern to format log\'s output is as follows:

log4j.appender.RA         


        

Answer 1

Another elegant solution with log4j2 is to use org.apache.logging.log4j.core.pattern.LogEventPatternConverter.

You can write a class like this

@Plugin(name = "ThreadIdConverter", category = "Converter")
@ConverterKeys({ "tid" })
public class ThreadIdConverter extends LogEventPatternConverter {

    protected ThreadIdConverter(String name, String style) {
        super(name, style);
    }

    @Override
    public void format(LogEvent event, StringBuilder toAppendTo) {
        toAppendTo.append(getThreadId());
    }

    protected String getThreadId() {
        long id = Thread.currentThread().getId();
        return Long.toHexString(id);
    }

    public static ThreadIdConverter newInstance(String[] options) {
        return new ThreadIdConverter("tid", "tid");
    }
}

In this way you are creating a new pattern tid and you can use it when you define your appender's layout

    
        
            %d{dd-MMM HH:mm:ss.SSS} %-7level [%5tid] %logger - %message%n
        
    

The last important thing to remember is how to activate your log4j2 plugin. To do it you have to add the package that contains your plugins in the log4j2 configuration file using the package attribute on Configuration node

    
        
            
                %d{dd-MMM HH:mm:ss.SSS} %-7level [%5tid] %logger - %message%n