I have experience of log4j, and have used a port of it called log4net in c#. In both cases I find it very useful to configure loggers at run time, by means of logger config files. For example you can increase the log level of a particular subsystem without a recompile.
I am searching for a logging framework for c++. Currently checking log4cxx and spdlog. I see that log4cxx can read its configuration from an xml file. Does this ability to configure at run time exist for spdlog?