Introduce signal handler

[benedikt-voelkel]

• introduce Exceptions

  • O2TunerStopOptimisation
  • O2TunerFatal

• catch SIGINT to make sure to find and kill all procs and children

• if in optimisation, one can issue a SIGTSTP via Ctrl-Z raises O2TunerStopOptimisation --> workers should catch and simply pass, hence terminate by themselves (currently a timeout of 10s is given from the outside)

[benedikt-voelkel]

Using SIGTSTP now (hence catching Ctrl-Z) to shutdown optimisation. Ctrl-C shuts down, as discussed What do you think @mconcas ?

[mconcas]

Using SIGTSTP now (hence catching Ctrl-Z) to shutdown optimisation. Ctrl-C shuts down, as discussed What do you think @mconcas

Provided that I think we should ultimately follow your taste, what about ^\ (SIGQUIT) instead? I have it on my ubuntu box to be checked if it is also available on macOS iterm2.

mconcas@box$ stty -a | grep intr
intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>;

One could expect that sending a SIGSTOP leaves the process in a state that can be resumed. Again is common habits vs "just learn that this keys combination is trapped in o2tuner". If signal 3 is unavailable, SIGSTP can also work.

To see if the signal is caught correctly I used this snippet and it was actually getting the ^\ combination.

import signal
import time

def signal_handler(sig, frame):
    print(f"Received signal {sig}")

for sig in (signal.SIGINT, signal.SIGTERM, signal.SIGQUIT):
    signal.signal(sig, signal_handler)

start_time = time.time()
while time.time() - start_time < 10:

[benedikt-voelkel]

Agreed, using SIGQUIT now. So Ctrl-Z would trigger SIGTSTP and might put process into bg as the user might be used to.

Did additional adjustments to avoid flake8 and pylint complaining about methods being too complex --> some modularisation optimise.py (which I think might make sense in any case)