Python Language Multithreading Advanced use of multithreads
Example
This section will contain some of the most advanced examples realized using Multithreading.
Advanced printer (logger)
A thread that prints everything is received and modifies the output according to the terminal width. The nice part is that also the "already written" output is modified when the width of the terminal changes.
#!/usr/bin/env python2
import threading
import Queue
import time
import sys
import subprocess
from backports.shutil_get_terminal_size import get_terminal_size
printq = Queue.Queue()
interrupt = False
lines = []
def main():
ptt = threading.Thread(target=printer) # Turn the printer on
ptt.daemon = True
ptt.start()
# Stupid example of stuff to print
for i in xrange(1,100):
printq.put(' '.join([str(x) for x in range(1,i)])) # The actual way to send stuff to the printer
time.sleep(.5)
def split_line(line, cols):
if len(line) > cols:
new_line = ''
ww = line.split()
i = 0
while len(new_line) <= (cols - len(ww[i]) - 1):
new_line += ww[i] + ' '
i += 1
print len(new_line)
if new_line == '':
return (line, '')
return (new_line, ' '.join(ww[i:]))
else:
return (line, '')
def printer():
while True:
cols, rows = get_terminal_size() # Get the terminal dimensions
msg = '#' + '-' * (cols - 2) + '#\n' # Create the
try:
new_line = str(printq.get_nowait())
if new_line != '!@#EXIT#@!': # A nice way to turn the printer
# thread out gracefully
lines.append(new_line)
printq.task_done()
else:
printq.task_done()
sys.exit()
except Queue.Empty:
pass
# Build the new message to show and split too long lines
for line in lines:
res = line # The following is to split lines which are
# longer than cols.
while len(res) !=0:
toprint, res = split_line(res, cols)
msg += '\n' + toprint
# Clear the shell and print the new output
subprocess.check_call('clear') # Keep the shell clean
sys.stdout.write(msg)
sys.stdout.flush()
time.sleep(.5)
