The logging.yml file is the configuration file for the pFlogger logging package used in GCHP. This package is a Fortran logger written and maintained by NASA Goddard. The pFlogger package is based on python logging and contains functions and classes that enable flexible event logging within GCHP components, including MAPL ExtData which handles input read.

GCHP logging is not the same as GEOS-Chem and HEMCO prints that go to the main GCHP log. It is hierarchical based on the severity of the event, with the level of severity per component used as criteria to print to the log file. The logging messages are sent to a separate file from the main GCHP log. The filename is specified in logging.yml as allPEs.log by default in the definition of the mpi_shared file handler.

Like the python logger, there are five levels of severity used to trigger messages. These are as follows, in order of most to least severe:


  2. ERROR


  4. INFO

  5. DEBUG

These levels are hierarchical, meaning each level triggers writing messages for all events with greater or equal severity. For example, if you specify CRITICAL you will get only messages triggered with that criteria since it is the most severe level. If you instead specify WARNING then you will trigger all events categorized as WARNING, ERROR, and CRITICAL.

Different GCHP components can have different levels of severity. These components are listed in the loggers section of the file. This helps hone in on problems you are experiencing in a specific component by allowing you to increase logger messages for one component only. This is particularly useful for debugging the component called CAP.EXTDATA in logging.yml which corresponds to the MAPL component that handles reading and regridding input files. When you experience a problem reading input files we recommend that you set the logger level for this component to DEBUG.

In addition to setting severity level per component you can also specify severity level based on processor. There are two options: root thread only and all threads. The root thread only option is root_level in the configuration file and will only trigger messages if the event is executed by the root processor. Using this option keeps the log file size down and can make reading the file easier. We recommend setting this option to DEBUG when investigating problems with input files.

The all threads option will log events for all processors. Each message will be prefixed by the processor number, e.g. 0000 for the root thread, 0001 for the next, and so on. Using this option can make the file size very large and difficult to read. However, you can grep the file for a processor number to isolate events of just one thread of interest, such as the one that appears in error message traceback.

For more information on the GCHP logger, including more advanced features, see documentation at https://github.com/Goddard-Fortran-Ecosystem/pFlogger/.