[Tutor] threading issues

[Chris Hallman]

You're right. I'm inexperienced with classes and threading. The example you
gave (www.wellho.net <http://www.wellho.net>) was the same example I used as
the basis for my script however I wasn't able to get it to work. I couldn't
figure out what the -q parameter is (it's not a valid parameter on the *nix
I have access to) and when I gave it an IP address range with reachable and
unreachable hosts, it reported them all as alive therefore this example
script isn't a good example. I was able to Google for more examples.

I was finally able to get my script to not show duplicate PINGs. I also
realized that my script was not PINGing all the hosts in the input file.
Here is my latest version:


import os, re, string, sys, threading, time
from threading import Thread
from time import strftime

ms = re.compile("Reply")
rpath = (r"c:\utils\network_ping_devices.txt")

if os.path.exists(r"c:\utils\network_ping_again.txt"):
rpath = (r"c:\utils\network_ping_again.txt")
wpath = (r"c:\logs\network_ping.out")
tpath = (r"c:\temp\ping.txt")
if os.path.exists(tpath):
os.remove(tpath)
temp = open(tpath, "w")
output = open(wpath, "a")
output.write("\n" + "Network PING test started -" + strftime(" %H:%M:%S %x")
+ "\n")
output.flush()

class PingIT(threading.Thread):
def __init__(self,rtr):
Thread.__init__(self)
self.rtr = rtr

def run(self):
pingaf = os.popen('ping -n 1 -w 3000 ' + self.rtr)
pingas = string.join(pingaf.readlines())
if ms.search(pingas):
# print (re.sub('\n','',self.rtr)) + " responded." #for debugging
return
else:
pingaf = os.popen('ping -n 1 -w 3000 ' + self.rtr)
pingas = string.join(pingaf.readlines())
if ms.search(pingas):
# print (re.sub('\n','',self.rtr)) + " responded." # for debugging
return
else:
temp.write(re.sub('\n','',self.rtr) + " did not respond.\n")

pinglist = []
for rtr in file(rpath):
current = PingIT(rtr)
pinglist.append(current)
current.start()

for pingle in pinglist:
pingle.join()

temp.close()
temp = open(tpath, "r")
lines = []
for line in temp:
lines.append(line.rstrip())
lines.sort()
for line in lines:
print >>output, line

output.write("Network PING test completed -" + strftime(" %H:%M:%S %x") +
"\n")
output.flush()
output.close()


All the hosts in the input file are sorted alphabetically but my results
were output out of order?! (possibly due to latency in PING responses or
some latency in the thread joining; not sure of either). I had to do the
crude temp output file so that I could sort the results, but it works!!


On 10/23/05, Kent Johnson <kent37 at tds.net> wrote:
>
> Chris Hallman wrote:
> >
> > I made a mistake in my first email..... I meant that I can't get fc to
> > write to the file. Here is the error:
> >
> > Traceback (most recent call last):
> > File "thread_test_ping.py", line 37, in ?
> > output.write(fc + " failures found.\n")
> > TypeError: unsupported operand type(s) for +: 'int' and 'str'
>
> This is a pretty easy error to understand. It is saying that you can't add
> an int and a string. Looking at your code, you are trying to add fc + "
> failures found.\n". fc is indeed an int. You have to change it to a string
> to be able to add it to another string. You can do this with the str()
> function. So the correct statement is
> output.write(str(fc) + " failures found.\n")
>
> >
> > I tried the suggestions you made, but I can't get it to work. Is this
> > what you meant?:
>
> No, not quite.
> >
> > #!/usr/bin/env python
> >
> > #Let us profile code which uses threads
> > import os, re, string, thread, threading, time
> > from time import strftime
> > #from threading import Thread
> >
> > class PingThread(threading.Thread):
> > def __init__(self, rtr):
> > threading.Thread.__init__(self)
> > self.rtr = rtr
>
> The init method initializes a PingThread. It is passed self as an
> argument, plus whatever parameters you pass in when you create the
> PingThread. You call the superclass constructor and save the value of the
> parameter. So far so good...but this next line is creating a PingThread, it
> belongs below in your loop.
>
> > PingThread(rtr).start(rtr)
> >
> > def run(self):
>
> Here you should reference self.rtr so you get the value that was stored in
> the call to __init__(), and similarly for each reference to rtr in the run
> method.
>
> > pingaf = os.popen('ping -n 1 -w 3 ' + rtr)
> > pingas = string.join(pingaf.readlines())
> > if ms.search(pingas):
> > print (re.sub('\n','',rtr)) + " responded." #for debugging
> > else:
> > pingaf = os.popen('ping -n 2 -w 3 ' + rtr)
> > pingas = string.join(pingaf.readlines())
> > if ms.search(pingas):
> > print (re.sub('\n','',rtr)) + " responded." # for
> > debugging
> > else:
> > fc=fc+1
> > output.write(re.sub('\n','',rtr) + " did not respond.\n")
> >
> > fc = 0 # failure counter
> > ms = re.compile("Reply from")
> > rpath = (r"c:\temp\py\network_ping_routers.txt")
> > if os.path.exists(r"c:\temp\py\network_ping_again.txt"):
> > rpath = (r"c:\temp\py\network_ping_again.txt")
> > wpath = (r"c:\temp\py\network_ping.out")
> > #os.system(r"c:\tnd\bin\cawto.exe -cat NetNet -n l17aesm1 forward blue
> > held Weekly ISDN testing has started -" + strftime(" %H:%M:%S %x") +
> "\n")
> > output = open(wpath, "a")
> > output.write("\n" + "\n" + "Network PING test started -" + strftime("
> > %H:%M:%S %x") + "\n")
> > output.flush()
> > threads = []
> > for rtr in file(rpath):
> > thread = PingThread()
> Here is where you need to call PingThread(rtr) to pass the value of rtr to
> the constructor.
>
> > thread.start()
> > threads.append(thread)
> > for thread in threads:
> > thread.join()
> > print fc # for debugging
> > output.write(fc + " failures found.\n")
> > output.write("\n" + "\n" + "Network PING test completed -" + strftime("
> > %H:%M:%S %x") + "\n")
> > output.close()
>
> I suspect that I am talking over your head and that maybe you are in over
> your head a bit here. If you don't understand the basics of classes and
> parameter passing you should spend some time with a tutorial that explains
> them, for example Alan Gauld's tutorial at
> http://www.freenetpages.co.uk/hp/alan.gauld/
>
> There is a brief introduction to threading here. It even uses your problem
> (pinging multiple servers) as the example.
> http://www.wellho.net/solutions/python-python-threads-a-first-example.html
>
> Kent
> http://www.kentsjohnson.com
>
> _______________________________________________
> Tutor maillist - Tutor at python.org
> http://mail.python.org/mailman/listinfo/tutor
>
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