Running a timer for few minutes in python

问题

I am trying to run a certain function "foo" every second. I have to do this for a few minutes (say 5).

The function foo() makes 100 HTTP Requests (which contains a JSON object) to the server and prints the JSON response.

In short, I have to make 100 HTTP requests per second for 5 minutes.

I have just started learning python, thus don't have extensive knowledge. This is what I have tried:

import threading
noOfSecondsPassed = 0
def foo():
   global noOfSecondsPassed
   # piece of code which makes 100 HTTP requests (I use while loop)
   noOfSecondsPassed += 1

while True:
   if noOfSecondsPassed < (300)  # 5 minutes
       t = threading.Timer(1.0, foo)
       t.start()

Due to multiple threads, the function foo isn't called 300 times but much much more than that. I have tried setting a lock too:

def foo():
  l = threading.Lock()
  l.acquire()
  global noOfSecondsPassed
  # piece of code which makes 100 HTTP requests (I use while loop)
  noOfSecondsPassed += 1
  l.release()

Rest of code is same as the previous code snippet. But this also does not work.

How do I do this?

Edit: Different Approach

I have tried this approach which worked for me:

def foo():
    noOfSecondsPassed = 0
    while noOfSecondsPassed < 300:
       #Code to make 100 HTTP requests
       noOfSecondsPassed +=1
       time.sleep(1.0)
foo()

Any disadvantages in doing so?

回答1:

I would use another approach which is easier I think.

Create 300 timer thread, each running 1 sec after the previous. The main loop is executed in almost an instant so the error factor is very low. Here's a sample Demo:

import datetime
import thread
import threading

def foo():
     print datetime.datetime.now()
     print threading.active_count()

for x in range(0,300): 
     t = threading.Timer(x + 1, foo)
     t.start()

This code output should look like this:

2012-10-01 13:21:07.328029
301
2012-10-01 13:21:08.328281
300
2012-10-01 13:21:09.328449
299
2012-10-01 13:21:10.328615
298
2012-10-01 13:21:11.328768
297
2012-10-01 13:21:12.329006
296
2012-10-01 13:21:13.329289
295
2012-10-01 13:21:14.329369
294
2012-10-01 13:21:15.329580
293
2012-10-01 13:21:16.329793
292
2012-10-01 13:21:17.329958
291
2012-10-01 13:21:18.330138
290
2012-10-01 13:21:19.330300                                                                                                                                                                                                                         
289                         
...

As you can see, each thread is launched about 1 sec after the previous and you are starting exactly 300 threads.

来源：https://stackoverflow.com/questions/12672750/running-a-timer-for-few-minutes-in-python

标签

python

multithreading

timer

python-multithreading