Comments about the use of the fine grained trace debugging are with
Since meas_modelfit uses the old debug<n> template for n = 10, 8, and 7, I have translated those into trace levels 5,4, and 3. They can be enabled using lsst.log.utils.traceSetAt(component_name, level). All traces <= level are enabled by this method.
The old pex_logging enabling mechanism was to call lsst.pex.logging.Debug(name, n) with n = 1, ..., 10. This method sets the debug level for name and anything higher on the hierarchy. For examble, lsst.pex.logging.Debug("meas.modelfit.optimizer", 10) seems to enable not only that level, but also "meas.modelfit.optimizer.Optimizer". I don't think that traceSetAt() has this same ability to set up the tree.
Hsin-Fang Chiang, can you confirm that this is true, that the trace for the individual level must be set individually?