# Debug configuration

> Jetty is instrumented with the debugging facilities of the com.mortbay.Base package. It is strongly recommended that Jetty developers also use this package. Debugging is activated and controlled by setting JVM properties. The main property is DEBUG, which if set with the -DDEBUG command line option to java, will enable debug output. Which classes generated debug can be controlled with the DEBUG_PATTERNS property, which if set to a comma separated list of strings, is used to select debug output from only those methods whose class or method name contain one of the strings as a substring. The LOG_OPTIONS property can be set to control the format of the debug output. The following options may be set:
>      t Timestamp log output
>      T Show the log tag name
>      L Show log label (thread, method and file names).
>      s Show indication of stack depth
>      S Stack trace for each output line (VERY VERBOSE)
>      O Place each log one One line of output
> Debug configuration can also be during run time. The DebugServlet can be configured into any Servlet server to allow easy manipulation of of debug settings.