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

I create my own appender and set Thread.currentThread().getId() to the MDC property. %X{threadId} should give me the thread id. This solution is working since 1.2.15. You can then attach AsyncAppender to this.

public class CurrentThreadIdAppender extends AppenderSkeleton implements AppenderAttachable {

    private final AppenderAttachableImpl appenders = new AppenderAttachableImpl();

...

    @Override
    protected void append(LoggingEvent event) {   
        synchronized (appenders) {
            event.setProperty("threadId", String.valueOf(Thread.currentThread().getId()));
            appenders.appendLoopOnAppenders(event);
        }
    }

...

}