Python 3.6
I want to take all input from a subprocess which I run with the subprocess
module. I can easily pipe this output to a log file, and it works great.
But, I want to filter out a lot of the lines (lots of noisy output from modules I do not control).
Attempt 1
def run_command(command, log_file):
process = subprocess.Popen(command, stdout=subprocess.PIPE,
stderr=subprocess.STDOUT, bufsize=1,
universal_newlines=True)
while True:
output = process.stdout.readline()
if output == '' and process.poll() is not None:
break
if output and not_noisy_line(output):
log_file.write(output)
log_file.flush()
return process.poll()
But this introduced a race condition between my subprocess and the output.
Attempt 2
I created a new method and a class to wrap the logging.
def run_command(command, log_file):
process = subprocess.run(command, stdout=QuiteLogger(log_file), stderr=QuiteLogger(log_file), timeout=120)
return process.returncode
class QuiteLogger(io.TextIOWrapper):
def write(self, data, encoding=sys.getdefaultencoding()):
data = filter(data)
super().write(data)
This does however just completely skip my filter function, my write method is not called at all by the subprocess. (If I call QuietLogger().write('asdasdsa')
it goes through the filters)
Any clues?