When running on 40,000 processes, then the message "INFO (Cactus): Increasing logging level from 0 to 3" is output 40,000 times. This is just crazy.
One solution would be to output this message (produced in CCTKi_SetLogLevel) only on one process. The only usage of this function seems to be from within CCTKi_CommandLineLoggingLevel, which produces this message when a logging level is specified on the command line, and this is executed for every process. We either have to disable the message inside CCTKi_SetLogLevel for processes other than, say, the root process, or we move the message out of that function, and up into CCTKi_CommandLineLoggingLevel, and there only do it on the root process. The effect would currently be the same, but the second option would provide a function which changes the loglevel without producing a message, while the former would always print a message on the root process (even if this might not be wanted). For this reason I propose the second option:
move the info call out of CCTKi_SetLogLevel, and into CCTKi_CommandLineLoggingLevel
making the info call in CCTKi_CommandLineLoggingLevel only on the root process