helperFunctions.process module

class helperFunctions.process.ExceptionSafeProcess(*args, reraise=True, **kwargs)

Bases: Process

ExceptionSafeProcess is a subtype of multiprocessing.Process with added exception handling. Opposed to what the name may suggest, the class does not make the process impervious to exceptions. Instead, it retrieves the exception of the subprocess and re-raises it. This allows reconstructing what happened in the subprocess.

The parameters for creating an instance of the class are the same as for multiprocessing.Process (see Python docs).

Parameters:

reraise (bool) –

property exception: tuple[Exception, str] | None

The exception that occurred in the process during execution and the respective stack trace. Is None if no exception occurred or the process was no yet executed.

Returns:

A tuple containing the exception and the stack trace or None.

run()

Starts the execution of the process. Any exception happening in the process will be reraised and may be retrieved by accessing ExceptionSafeProcess.exception.

helperFunctions.process.check_worker_exceptions(process_list, worker_label, worker_function=None)

Iterate over the process_list and check if exceptions occurred. In case of an exception, the process and its children will be terminated. If throw_exceptions in the FACT configuration is set to false, the worker may be restarted by passing a function (if the value is not set, the worker will not be restarted). In this case, the function will always return False. If throw_exceptions is set to true and an exception occurs, the worker will not be restarted and the return value is True.

Parameters:

  • process_list (list[ExceptionSafeProcess]) – A list of worker processes.

  • worker_label (str) – A label used for logging (e.g. Analysis or Unpacking).

  • worker_function (Callable | None) – A function used for restarting the worker (optional).

Returns:

True if an exception occurred in any process and throw_exceptions in the FACT configuration is set to true and False otherwise.

Return type:

bool

helperFunctions.process.complete_shutdown(message=None)

Shutdown all FACT processes (of the currently running component) by sending a signal to the process group.

Parameters:

message (str | None) – Optional message to be displayed before the shutdown.

Return type:

None

helperFunctions.process.new_worker_was_started(new_process, old_process)

Check if a worker process was restarted by comparing old and new process.

Parameters:
Returns:

True if the processes match and False otherwise.

Return type:

bool

helperFunctions.process.start_single_worker(process_index, label, function)

Starts a new worker process executing function and returns it. Used for unpacking and analysis workers in the FACT backend.

Parameters:

  • process_index (int) – The index of the process in the process list of the scheduler.

  • label (str) – A label used for logging (e.g. Analysis or Unpacking).

  • function (Callable) – The function, that gets executed by the worker process.

Returns:

The running process.

Return type:

ExceptionSafeProcess

helperFunctions.process.stop_process(process, timeout=10.0)

Try to stop a single process gracefully. If it does not stop until timeout is reached, kill it.

Parameters:

  • process (Process) –

  • timeout (float) –

helperFunctions.process.stop_processes(processes, timeout=10.0)

Try to stop processes gracefully in parallel. If a process does not stop until timeout is reached, kill it.

Parameters:

  • processes (list[Process]) – The list of processes that should be stopped.

  • timeout (float) – Timeout for joining the process in seconds.

helperFunctions.process.terminate_process_and_children(process)

Terminate a process and all of its child processes.

Parameters:

process (Process) – The process to be terminated.

Return type:

None