CleanBasf2Execution Class Reference

Public Member Functions
def	__init__ (self, timeout=10)
def	start (self, command)
def	wait (self)
def	signal_handler (self, signal_number, signal_frame)
def	kill (self)
def	wait_for_process (self, process_list=None, timeout=None, minimum_delay=1)
def	install_signal_handler (self)

Static Public Member Functions
def	has_process_ended (process)

Public Attributes
	timeout
	Maximum time the process is allowed to stay alive after SIGTERM has been sent.

Private Attributes
	_handled_processes
	The processes handled by this class.
	_handled_commands
	The commands related to the processes.

Detailed Description

Helper class to call a given (basf2) command via subprocess
and make sure the process is killed properly once a SIGINT or SIGTERM signal is
send to the main process.
To do this, the basf2 command is started in a new session group, so all child processes
of the basf2 command will also be killed.

When the main process receives a termination request via an SIGINT or SIGTERM,
a SIGINT is sent to the started basf2 process.
If the process is still alive after a given timeout (10 s by default),
it is killed via SIGKILL and all its started child forks with it.
After a normal or abnormal termination, the run() function returns the exit code
and cleanup can happen afterwards.

ATTENTION: In some rare cases, e.g. when the terminate request happens during a syscall,
the process can not be stopped (see uninterruptable sleep process state, e.g. in
https://stackoverflow.com/questions/223644/what-is-an-uninterruptable-process).
In those cases, even a KILL signal does not help!

The class can be used in a typical main method, e.g.

    from hlt.clean_execution import CleanBasf2Execution

    if __name__ == "__main__":
        execution = CleanBasf2Execution()
        try:
            execution.start(["basf2", "run.py"])
            execution.wait()
        finally:
            # Make sure to always do the cleanup, also in case of errors
            print("Do cleanup")

Definition at line 16 of file clean_execution.py.

Constructor & Destructor Documentation

__init__()

def __init__	(		self,
			timeout = 10
	)

Create a new execution with the given parameters (list of arguments)

Definition at line 51 of file clean_execution.py.

    def __init__(self, timeout=10):
        """
        Create a new execution with the given parameters (list of arguments)
        """
        
        self._handled_processes = []
        
        self._handled_commands = []
        
        self.timeout = timeout
 

Member Function Documentation

has_process_ended()

def has_process_ended (   process )

static

Check if the handled process has ended already.
This functions does not wait.

I would rather use self._handled_process.wait() or poll()
which does exactly the same.
However: the main process is also waiting for the return code
so the threading.lock in the .wait() function will never aquire a lock :-(

Definition at line 179 of file clean_execution.py.

install_signal_handler()

def install_signal_handler

(

self

)

Set the signal handlers for SIGINT and SIGTERM to out own one.

Definition at line 168 of file clean_execution.py.

kill()

def kill

(

self

)

Clean or hard shutdown of all processes.
It tries to kill the process gracefully but if it does not react after a certain time,
it kills it with a SIGKILL.

Definition at line 96 of file clean_execution.py.

signal_handler()

def signal_handler	(		self,
			signal_number,
			signal_frame
	)

The signal handler called on SIGINT and SIGTERM.

Definition at line 90 of file clean_execution.py.

start()

def start	(		self,
			command
	)

Add the execution and terminate gracefully/hard if requested via signal.

Definition at line 62 of file clean_execution.py.

wait()

def wait

(

self

)

Wait until all handled calculations have finished.

Definition at line 76 of file clean_execution.py.

wait_for_process()

def wait_for_process	(		self,
			process_list = None,
			timeout = None,
			minimum_delay = 1
	)

Wait maximum "timeout" for the process to stop.
If it did not end in this period, returns False.

Definition at line 145 of file clean_execution.py.

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The documentation for this class was generated from the following file:

• hlt/scripts/hlt/clean_execution.py