How multiprocess share a common queue?

Question

I want to start 4 process which put an integer in queue when counter is divisible by 100.Same time another process continuously read it and print it.Please correct my code to run...I am getting an error ['Queue' object is not iterable]

from multiprocessing import Lock, Process, Queue, current_process
import time
import queue 
def doFirstjob(process_Queue):
 i=0
 while True:
 if i%100==0:
 process_Queue.put(i)
 else:
 i+=1
def doSecondjob(process_Queue):
 while(1):
 if not process_Queue.Empty:
 task = process_Queue.get()
 print("task: ",task)
 else:
 time.sleep(0.2)
def main():
 number_of_processes = 4
 process_Queue = Queue()
 processes = []
 process_Queue.put(1)
 q = Process(target=doSecondjob, args=(process_Queue))
 q.start()
 for w in range(number_of_processes):
 p = Process(target=doFirstjob, args=(process_Queue))
 processes.append(p)
 p.start()
if __name__ == '__main__':
 main()

• Sach: put a comma after process_Queue in args,

Answer 1

You were getting error because Process was expecting a list/tuple in arguments/args.

Also instead of Empty it should be empty.

change the code to below.

from multiprocessing import Lock, Process, Queue, current_process
import time
import queue 
def doFirstjob(process_Queue):
 i=0
 while True:
 print("foo")
 if i%100==0:
 process_Queue.put(i)
 else:
 i+=1
def doSecondjob(process_Queue):
 while(1):
 print("bar")
 if not process_Queue.empty:
 task = process_Queue.get()
 print("task: ",task)
 else:
 time.sleep(0.2)
def main():
 number_of_processes = 4
 process_Queue = Queue()
 processes = []
 process_Queue.put(1)
 q = Process(target=doSecondjob, args=(process_Queue,))
 q.start()
 for w in range(number_of_processes):
 p = Process(target=doFirstjob, args=(process_Queue,))
 processes.append(p)
 p.start()
if __name__ == '__main__':
 main()