Hi,

we often need to change log level thresholds to investigate a problem in a running system. Right now, we do that by using

<configuration  scan="true" scanPeriod="30 seconds">

and then editing the logback.xml file by hand (i.e. using a text editor or Sed or Perl).  I wonder if there is a better way to accomplish this.  I know that we can e.g. use

  <root level="${rootLevel}"/>

but what I do not yet understand is:

1. Can I modify the value if this variable via some Java API from within my application?
2. Do we still need the scan="true"​ attribute or will the "rootLevel" variable be evaluated every time the logger is used?
3. Is there a measurable performance impact by using variables in that manner?