Logging parallel threads in logback

Question

I\'ll try to make a brief description of my Selenium framework so that I can explain my problem.

I use Selenium 2 (current version 2.3.1) + test

Answer 1

If you would like an alternative to the unpredictable names you get with %thread as I usually do, you can use simple thread-local IDs. Its much easier on the eyes. This will work with logback...

public class ThreadIdConverter extends ClassicConverter {
  private static int nextId = 0;
  private static final ThreadLocal threadId = new ThreadLocal() {    
    @Override
    protected String initialValue() {
      int nextId = nextId();
      return String.format("%05d", nextId);
    }
  };

  private static synchronized int nextId() {
    return ++nextId;
  }

  @Override
  public String convert(ILoggingEvent event) {
    return threadId.get();
  }
}

Then put this simple line in your logback XML:

Set your pattern something like this (notice "tid"):

%d{HH:mm:ss.SSS} [%tid] %-5level - %msg%n

And your logs will look like this:

10:32:02.517 [00001] INFO something here
10:32:02.517 [00002] INFO something here
10:32:02.517 [00003] INFO something here
10:32:02.517 [00001] INFO something more here 
10:32:02.517 [00001] INFO something more here

You can do this with any logger that supports custom extensions. Hope it helps.