Check if servers are available using one client in python

Question

I want to write a code to achieve below

I have written a client(c1) and 3 servers (s1, s2 and s3) in python.

C1 will check if it is able to connect to s1. If yes, it will sleep for 2 mins. It will wake up again after 2 mins and will check if s1 is connectable. If no, then it will check s2. If s2 is listening then c1 will go to sleep for 2 mins. And this will keep on happening.

Now, my issue is, I can check s1 but not able use if else coding

s=socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
    try:
        s.connect(('111.111.1.1', 2222))
        time.sleep(120) 
    except Exception as inst:
        print("not ready1")   
        try:
            s.connect(('11.22.22.2', 2212))
            time.sleep(120) 
        except Exception as inst:
            print("not ready2")
            try:
                s.connect(('1.1.1.33', 1234)) 
                time.sleep(120) 
            except Exception as inst:
                print("not ready3")

I want to achieve this using if else looping. And also make sure that this code executes infinite time. Right now, it will execute only once.

Using except Exception as e: is discouraged, it's not a good idea. I'm not sure I understand what the issue is, can you be more specific? — AMC
– AMC, Commented Jan 7, 2020 at 21:20
I just want to check if c1 is able to connect to s2 or not. If not then c1 should check s3. — Newbie
– Newbie, Commented Jan 7, 2020 at 21:23

Daniel Yohan · Accepted Answer · 2020-01-07 21:27:56Z

2

Would that fit you?

import socket
import time


def run(ip, port):
    try:
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.connect((ip, port))
        return True
    except Exception:
        return False


while True:
    if run('111.111.1.1', 2222):
        print('s1 read')
        time.sleep(120)
    elif run('11.22.22.2', 2222):
        print('s2 read')
        time.sleep(120)
    else:
        print('s1 and s2 not read')

answered Jan 7, 2020 at 21:27

Daniel Yohan

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2 Comments

Newbie Over a year ago

I am using the function as a thread. Not sure if I can do this using threads

Daniel Yohan Over a year ago

I have no problem using with thread, but you will need to change this algorithm

FireByTrial · Accepted Answer · 2020-01-07 21:31:53Z

0

edit: after thinking about this, you will hit recursion depth with the old result, you would have to use a loop with the code as presented. there is another answer that shows a good result for that

could you put the code in a function and call recursively? I'm not 100% clear on what you want to do, I think you want to check 3 servers, 1 at a time 2 minutes apart.

s=socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
def recursive_function():
    try:
        s.connect(('111.111.1.1', 2222))
        time.sleep(120) 
    except OSError as inst:
        print("not ready1") 
        try:
            s.connect(('11.22.22.2', 2212))
            time.sleep(120) 
        except OSError as inst:
            print("not ready2") 
    return recursive_function()
recursive_function()

Also, as others have posted, catching Exception is not a good idea unless you specifically need to catch that (usually for cleanup then raise the exception again) there is lots of room for improvement in this function as well, I just made it 'passible' but I would not say this is a good result.

you may want to read up on functional programming methods, it sounds like this is what you are trying to do.

answered Jan 7, 2020 at 21:31

FireByTrial

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2 Comments

Maurice Meyer Over a year ago

You can't have an infinite recursive loop in Python, in case all servers are responding forever. I guess you are running into an maximum recursion depth exceeded error.

AMC Over a year ago

Is OSError the right exception to check for in this case? I'm not very familiar with the socket library.

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