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Launching processes

The Simvue client can launch and monitor commands traditionally launched on the command line via the add_process method. The command can be provided in a number of ways.

The simplest form is to provide a set of strings defining the command: 

run.add_process("my_process", "echo", "Hello World!")

Specifying command components explicitly

Alternatively we can be more explicit in defining how the command is structured:

run.add_process(
    identifier="my_model_run",
    executable="bash",
    script="run.sh",
    input_file="input.dat",
    env={"DATA_FILE_DIR": os.getcwd()}
)

when arguments are specified for script and input_file these are uploaded as 'code' and 'input' object types to Simvue automatically. Additional keyword arguments are treated as options to the command itself:

run.add_process(
    identifier="run_third_party_python",
    executable="python",
    script="code_exe.py",
    input_file="input.dat",
    debug=True,             # Boolean options become flags
    output_dir=os.getcwd(), # Others become options
)

The command executed would then have the form: 

python code_exe.py input.dat --debug --output-dir $PWD

Termination triggers and callbacks

In addition the add_process method includes parameters relating to when the process completes. The argument completion_callback can be set to be a function of the form:

def completion_callback_func(status_code: int, std_out: str, std_err: str) -> None:
    ...

and will be called once the process has terminated.

Alternatively completion_trigger is a multiprocessing.Event or threading.Event object which will be set once the process completes, this can then be used as a trigger:

trigger = threading.Event()
run.add_process("my_process", executable="bash", c="echo 'Hello World!'", completion_trigger=trigger)

while not trigger.is_set():
    time.sleep(10)

Note due to differences in Python between UNIX and Windows based systems completion_trigger is not supported on Windows at this time.

Monitoring

When a process is added to a Simvue run:

  • The executed command is added to the metadata for that run.
  • Any files specified by input_file or script are uploaded as artifacts.
  • If not empty files, the stdout and stderr for the process are uploaded as artifacts.
  • User alerts are created which are set to either "ok" or "critical" depending on process exit status.