[Core] Add Process for Flushing Streams

[matekelemen]

Nearly every MainKratos.py I've ever seen begins by defining an AnalysisStage that flushes stdout regularly. In this PR, I'm adding a process that does the same thing to make the main python scripts cleaner.

[philbucher]

I would make this part of the analysis stage, see what I did in the CoSim Analysis Stage. I quite like the solution, it is simple yet worked well for me

[philbucher]

In my experience also a lot of stuff gets stuck in the logger:

Kratos/applications/CoSimulationApplication/python_scripts/co_simulation_analysis.py

Lines 99 to 102 in 245da2c

	@staticmethod
	def Flush():
	sys.stdout.flush()
	KM.Logger.Flush()

[matekelemen]

wait, which stream is the logger using? I thought it was writing to stdout.

[sunethwarna]

It depends on how the Logger is constructed. It can use to have std::out, or std::fstream or other stream types as well. So using as @philbucher mentioned makes sense.

[sunethwarna]

Kratos/applications/RANSApplication/python_scripts/formulations/utilities.py

Lines 335 to 346 in aacb6c1

	def AddFileLoggerOutput(log_file_name):
	file_logger = Kratos.FileLoggerOutput(log_file_name)
	default_severity = Kratos.Logger.GetDefaultOutput().GetSeverity()
	Kratos.Logger.GetDefaultOutput().SetSeverity(Kratos.Logger.Severity.WARNING)
	Kratos.Logger.AddOutput(file_logger)
	return default_severity, file_logger
	def RemoveFileLoggerOutput(default_severity, file_logger):
	Kratos.Logger.Flush()
	Kratos.Logger.RemoveOutput(file_logger)
	Kratos.Logger.GetDefaultOutput().SetSeverity(default_severity)

[matekelemen]

I would make this part of the analysis stage, see what I did in the CoSim Analysis Stage. I quite like the solution, it is simple yet worked well for me

fine by me, it's a matter of whether the @KratosMultiphysics/technical-committee is ok with touching AnalysisStage.

[rubenzorrilla]

I'd follow @philbucher 's suggestion as it keeps the "automatic" handling of the flush, which I find is more convenient for the user.