Signals

Parthenon handles several operating system signals. Generally, it attempts to exit gracefully (saving simulation state), but upon receiving repeated signals it will exit immediately like any other program.

• If Parthenon catches a SIGINT, SIGTERM, or SIGALRM, it will attempt to exit gracefully at the end of the current step, after outputting any final simulation output files. These are the signals sent with ^C, by Slurm when a job has reached its walltime limit, or after the time specified on the command line with -t HH:MM:SS.

• If Parthenon catches three SIGINT or SIGTERM signals during a single step, it will exit immediately with a PARTHENON_ERROR. So, if an application is misbehaving, three SIGINT``s with ``^C will end it immediately.

In addition to signals, Parthenon applications will react to special files placed in the output directory.

• Creating/touching a new file with the name output_now in the working directory of a running application will cause it to write output files with a now id rather than a number. After the output is written. the output_now file is removed and the simulation continues normally. The user can repeat the process any time by creating a new output_now file.

• Creating a file named stop_now will stop a running simulation at the end of the current step, in exactly the same way as sending a single SIGINT.

Signal handling is implemented in utils/signal_handler.cpp.