fcntl in py 2.6

Posted on
Fri May 01, 2015 12:13 am
kw123 offline
User avatar
Posts: 7695
Joined: May 12, 2013
Location: Dallas, TX

fcntl in py 2.6

In py 2.7 the attached test.py program reads the stream of data generated by pgm.py(*) nicely, but NOT when used under py2.6 (in plugin or standalone program)

python program is started with
/usr/bin/python2.6 test.py or ... python2.7 test.py

test.py:
Code: Select all
import fcntl, os, subprocess, time
p = subprocess.Popen([pythonPath, '/xxx/yyy/pgm.py'], stdout = subprocess.PIPE, shell = False)
flags = fcntl.fcntl(p.stdout, fcntl.F_GETFL) # get current p.stdout flags
fcntl.fcntl(p.stdout, fcntl.F_SETFL, flags | os.O_NONBLOCK)
while True:
   try:
      time.sleep(1)
      print "hello"
      xx =  os.read(p.stdout.fileno(), 1024)
      if len(xx) > 5: print xx
   except OSError:
      time.sleep(5)

(*) pgm.py:
Code: Select all
import time
while true:
  print "abc"
  sys.stdout.flush()
  time.sleep(3)


any advice?

thx

Karl

Posted on
Fri May 01, 2015 3:52 am
autolog offline
Posts: 3506
Joined: Sep 10, 2013
Location: West Sussex, UK [GMT aka UTC]

Re: fcntl in py 2.6

Hi Karl,

I am not sure exactly what output you are expecting but in seems similar in python2.6 vs python2.7.

I had some difficulty exactly replicating your test. I had to make changes to pgm.py to get it working:
Code: Select all
import time
import sys
while True:
  print "abc"
  sys.stdout.flush()
  time.sleep(3)
i.e. add import sys and change true to True

Also when running test.pgm, it couldn't find pythonPath so I set it to '/usr/bin/python2.6' and '/usr/bin/python2.7' before each test as appropriate. I added in a print statement to print out the value of the pythonPath variable as a double check. :)

The output I got from a 2.6 test was:
$ python2.6 test.py
pythonPath used for test: /usr/bin/python2.6
hello
hello
hello
abc
abc

hello
hello
abc
abc

hello
hello
hello
abc
abc

hello
hello
hello
abc
abc

hello
hello
abc
abc

hello

and the output from a 2.7 test was:
$ python2.7 test.py
pythonPath used for test: /usr/bin/python2.7
hello
hello
hello
abc
abc

hello
hello
abc
abc

hello
hello
hello
abc
abc

hello
hello
abc
abc

hello
hello
hello
abc
abc

hello


Does this help at all?

Posted on
Fri May 01, 2015 8:21 am
kw123 offline
User avatar
Posts: 7695
Joined: May 12, 2013
Location: Dallas, TX

Re: fcntl in py 2.6

I stripped down my real py program. :oops: .

and when I actually do it very simple it actually works. thanks for debugging, ...

now I have to step by step add back functionality.

Karl

Page 1 of 1

Who is online

Users browsing this forum: No registered users and 1 guest