Hi,
I have a Tkinter program where I can fire up a commandline program which could
run for quite a while (let's say 15 minutes or more). While the program is
running, I would like to show the output that I normally see in the terminal
(actually, the target platform is windows but now I am on Linux) in a text
entry widget. The main purpose of this is to show that "something is
happening".
Anyway, below I tried to make a simplified version, without Tkinter. I fire up
the commandline process in a separate thread, and I try to append lines of the
output to a deque. The 'ls' command returns 2964 lines on my system. So I
expect the deque to contain less items, because every time the while loop in
process() sleeps, it would miss a few items. But it doesn't! It's like the ls
output is returned as one chunk.
What am I doing wrong?
Thanks!
Albert-Jan
from subprocess import Popen, PIPE
from threading import Thread
from collections import deque
import sys
import time
import os.path
def process(dq):
"""Run a commandline program, with lots of output"""
cwd = os.path.dirname(sys.executable)
proc = Popen("ls -lF", cwd=cwd, shell=True, stdout=PIPE, stderr=PIPE)
#print len(proc.stdout.readlines()) # 2964
output = errors = None
while True:
try:
#output, errors = proc.communicate() # "Wait for process to
terminate."
output = proc.stdout.read() # docs: "Use communicate() rather than
.stdin.write, .stdout.read or .stderr.read"
errors = proc.stderr.read()
proc.stdout.flush()
except ValueError:
break
finally:
if errors:
raise RuntimeError(str(errors))
if output:
dq.append(output)
time.sleep(0.0001)
if not output:
break
def update(dq):
"""This is supposed to return a new, not necessarily contiguous, chunk of
output"""
if dq:
result = dq.pop()
print time.asctime().center(79, "*")
print result
return result
if __name__ == "__main__":
dq = deque()
output_thread = Thread(target=process, args=(dq,), name="output_thread")
#output_thread.setDaemon(True)
output_thread.start()
lines = []
while output_thread.is_alive():
update(dq)
time.sleep(0.1)
if not dq:
break
for item in dq:
lines += item.splitlines()
output_thread.join()
print len(lines)
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