Examples of log4net PatternLayout output

24th May 2009

log4net has a lot of options when it comes to defining what you write to your log. While all the patterns are documented, it is useful to see a sample output from some code. Here is the output produced from some of the patterns available:

Of particular interest is the difference between logger and type. For the SubClass class, they result in the same output, but for the BaseClass logger is a lot more verbose (especially if your generic type happens to be from a strongly-signed assembly!). Using logger will give more detailed information but at the expense of larger log files.

Methodology

Because some of the patterns vary their output if you are in a base class or an inherited class, I created a simple class hierarchy, and also included use of generics.

public class BaseClass<T>
{
   private ILog _log;

   public BaseClass()
   {
       _log = LogManager.GetLogger(typeof (BaseClass<T>));
   }

   public virtual string MyMethod(T stuff)
   {
       _log.Debug("BaseClass");

       return "ha";
   }
}

public class SubClass : BaseClass<string>
{
   private ILog _log;

   public SubClass()
   {
       _log = LogManager.GetLogger(typeof (SubClass));
   }

   public override string MyMethod(string stuff)
   {
       _log.Debug("SubClass");

       return "ho ho";
   }
}

The project that included this code was strongly signed, to allow any effect this might cause to be evident.