I need to run my Python program forever in an infinite loop..
Currently I am running it like this -
#!/usr/bin/python
import time
# some python code that I want
# to keep on running
# Is this the right way to run the python program forever?
# And do I even need this time.sleep call?
while True:
time.sleep(5)
Is there any better way of doing it? Or do I even need time.sleep call?
Any thoughts?
Yes, you can use a while True: loop that never breaks to run Python code continually.
However, you will need to put the code you want to run continually inside the loop:
#!/usr/bin/python
while True:
# some python code that I want
# to keep on running
Also, time.sleep is used to suspend the operation of a script for a period of time. So, since you want yours to run continually, I don't see why you would use it.
How about this one?
import signal
signal.pause()
This will let your program sleep until it receives a signal from some other process (or itself, in another thread), letting it know it is time to do something.
I know this is too old thread but why no one mentioned this
#!/usr/bin/python3
import asyncio
loop = asyncio.get_event_loop()
try:
loop.run_forever()
finally:
loop.close()
sleep is a good way to avoid overload on the cpu
not sure if it's really clever, but I usually use
while(not sleep(5)):
#code to execute
sleep method always returns None.
Here is the complete syntax,
#!/usr/bin/python3
import time
def your_function():
print("Hello, World")
while True:
your_function()
time.sleep(10) #make function to sleep for 10 seconds
for OS's that support select:
import select
# your code
select.select([], [], [])
I have a small script interruptableloop.py that runs the code at an interval (default 1sec), it pumps out a message to the screen while it's running, and traps an interrupt signal that you can send with CTL-C:
#!/usr/bin/python3
from interruptableLoop import InterruptableLoop
loop=InterruptableLoop(intervalSecs=1) # redundant argument
while loop.ShouldContinue():
# some python code that I want
# to keep on running
pass
When you run the script and then interrupt it you see this output, (the periods pump out on every pass of the loop):
[py36]$ ./interruptexample.py
CTL-C to stop (or $kill -s SIGINT pid)
......^C
Exiting at 2018-07-28 14:58:40.359331
interruptableLoop.py:
"""
Use to create a permanent loop that can be stopped ...
... from same terminal where process was started and is running in foreground:
CTL-C
... from same user account but through a different terminal
$ kill -2 <pid>
or $ kill -s SIGINT <pid>
"""
import signal
import time
from datetime import datetime as dtt
__all__=["InterruptableLoop",]
class InterruptableLoop:
def __init__(self,intervalSecs=1,printStatus=True):
self.intervalSecs=intervalSecs
self.shouldContinue=True
self.printStatus=printStatus
self.interrupted=False
if self.printStatus:
print ("CTL-C to stop\t(or $kill -s SIGINT pid)")
signal.signal(signal.SIGINT, self._StopRunning)
signal.signal(signal.SIGQUIT, self._Abort)
signal.signal(signal.SIGTERM, self._Abort)
def _StopRunning(self, signal, frame):
self.shouldContinue = False
def _Abort(self, signal, frame):
raise
def ShouldContinue(self):
time.sleep(self.intervalSecs)
if self.shouldContinue and self.printStatus:
print( ".",end="",flush=True)
elif not self.shouldContinue and self.printStatus:
print ("Exiting at ",dtt.now())
return self.shouldContinue
If you mean run as service then you can use any rest framework
from flask import Flask
class A:
def one(port):
app = Flask(__name__)
app.run(port = port)
call it:
one(port=1001)
it will always keep listening on 1001
* Running on http://127.0.0.1:1001/ (Press CTRL+C to quit)
