How to give a variable from _While.py to __scheduler.py in this multithreading Szenario?
I tried so much stuff but nothing seems to be working.
Thread.py
from multiprocessing import Process
import _While
import _Scheduler
if __name__ == '__main__':
p1 = Process(target=_While.main)
p1.start()
p2 = Process(target=_Scheduler.main)
p2.start()
_While.py
import time
def main():
while True:
print "while"
time.sleep(0.5)
"""getting button status"""
"""giving button status to _Scheudler._scheduler"""
__Scheduler.py
import logging
import time
from apscheduler.scheduler import Scheduler
from _While import """button status"""
def _scheduler():
print "scheduler"
while """button status"""==True:
print "Button is pressed"
time.sleep(0.5)
def main():
logging.basicConfig()
scheduler = Scheduler(standalone=True)
scheduler.add_interval_job(_scheduler, seconds=2)
scheduler.start()
if __name__ == '__main__':
main()
Solution:
Thread.py
from multiprocessing import Process, Value, Array
import time
import _While
import _Scheduler
if __name__ == '__main__':
num = Value('d', 0.0)
arr = Array('i', range(10))
p1 = Process(target=_While.main, args=(num, arr))
p1.start()
p2 = Process(target=_Scheduler.main, args=(num, arr))
p2.start()
p1.join()
p2.join()
print num.value
_While
import time
def main(num, arr):
while True:
print "while"
num.value = 1
time.sleep(10)
"""getting button status"""
"""giving button status to _Scheudler._scheduler"""
__Scheduler.py
import logging
from apscheduler.scheduler import Scheduler
def _scheduler(num, arr):
while True:
print num.value
if num.value == 1:
print "mongo"
num.value = 0
break
def main(num, arr):
logging.basicConfig()
scheduler = Scheduler(standalone=True)
scheduler.add_interval_job(_scheduler, args=(num, arr), seconds=2)
scheduler.start()
if __name__ == '__main__':
main()
The only problem left is that I can't use Value without using Array
Create an instance of multiprocessing.Value in Threads.py just before you create p1 and p2, then pass the instance of Value as args to both p1 and p2 and change the main() method of _While.py and _Scheduler.py to accept the new Value parameter.
Similar to how it is done here http://docs.python.org/2/library/multiprocessing.html#sharing-state-between-processes
You could also use Queues or Pipes as suggested by Euegene C. an example can be found here http://docs.python.org/2/library/multiprocessing.html#exchanging-objects-between-processes
Related
hellow,
please some help.
i want to take variables when using repeating statement.
Actually in my code, there are so many variables and function to handle variables.
so i have to use multiprocess for some reason, but it's doesn't work for what i want.
below is simple code,
please help me.
from multiprocessing import Process, Manager
import time
def a(final_list):
c=0
while True:
c += 1
final_list.append(c)
time.sleep(1)
print(final_list)
def b(final_list):
while True:
print(final_list[-1])
time.sleep(1)
if __name__ == '__main__':
manager = Manager()
final_list = []
final_list = manager.list()
#print(a)
p1 = Process(target=a, args=(final_list,))
p2 = Process(target=b, args=(final_list,))
p1.start()
time.sleep(3)
p2.start()
I think you forgot to use join() for the processes. try this:
from multiprocessing import Process, Manager
import time
def a(final_list):
c=0
while True:
c += 1
final_list.append(c)
time.sleep(1)
print(final_list)
def b(final_list):
while True:
print(final_list[-1])
time.sleep(1)
if __name__ == '__main__':
with Manager() as manager:
final_list = manager.list()
p1 = Process(target=a, args=(final_list,))
p2 = Process(target=b, args=(final_list,))
p1.start()
time.sleep(3)
p2.start()
p1.join()
p2.join()
I have two functions and needed the return values to proceed with the further part of the script...but currently my code giving only the output of the first function...
import multiprocessing
def gm(name):
h = "Good Morning"+str(name)
qout.put(h)
def sal(name):
k="Hi "+str(name)
qout.put(k)
if __name__ == '__main__':
qout = multiprocessing.Queue()
p1 = multiprocessing.Process(target=gm, args=("ashin",))
p2 = multiprocessing.Process(target=sal, args=("ashin",))
p1.start()
p2.start()
p1.join()
p2.join()
result = qout.get()
#output - "Good Morning ashin"
#required output - "Good Morning ashin" & "Hi ashin"
Appreciate your help......
qout.get() gets you the first element from queue. I do not know the bigger picture of what you're are trying to achieve, but you can get all elements from queue like in the following.
from multiprocessing import Process, Queue
def gm(name):
h = "Good Morning"+str(name)
qout.put(h)
def sal(name):
k="Hi "+str(name)
qout.put(k)
if __name__ == '__main__':
qout = Queue()
p1 = Process(target=gm, args=("ashin",))
p2 = Process(target=sal, args=("ashin",))
p1.start()
p2.start()
p1.join()
p2.join()
list1 = []
while not qout.empty():
list1.append(qout.get())
temp = list(map(str, list1))
print(" & ".join(temp))
output
Hi ashin & Good Morningashin
Instead of managing your own output queue, just use the latest Python 3 concurrency features:
from concurrent.futures import as_completed, ProcessPoolExecutor
def gm(name):
return f'Good Morning {name}'
def sal(name):
return f'Hi {name}'
if __name__ == '__main__':
with ProcessPoolExecutor() as exe:
futures = [exe.submit(x, 'ashin') for x in (gm, sal)]
for future in as_completed(futures):
print(future.result())
The following code communicates a list between processes by using SharedMemoryManager, but I don't know why it causes EOFError: Ran out of input
from multiprocessing.managers import SharedMemoryManager
from multiprocessing import Process
import time
def train(sl, process_name):
for i in range(100):
sl[0] = i
time.sleep(0.2)
def debug3d(cls, process_name):
for i in range(100):
print("from", process_name, cls)
time.sleep(0.2)
class Cls:
def __init__(self, smm):
self.smm = smm
if __name__ == "__main__":
with SharedMemoryManager() as smm:
sl = smm.ShareableList([1])
p1 = Process(target=train, args=(sl, "process1"))
instance = Cls(smm)
p2 = Process(target=debug3d, args=(instance, "process2"))
p1.start()
p2.start()
p1.join()
p2.join()
however, when I pass shareableList as a parameter of debug3d, it works without an error
from multiprocessing.managers import SharedMemoryManager
from multiprocessing import Process
import time
def train(sl, process_name):
for i in range(100):
sl[0] = i
time.sleep(0.2)
def debug3d(sl, process_name):
user_cls = Cls(sl)
for i in range(100):
print("from", process_name, user_cls.smm)
time.sleep(0.2)
class Cls:
def __init__(self, smm):
self.smm = smm
if __name__ == "__main__":
with SharedMemoryManager() as smm:
sl = smm.ShareableList([1])
p1 = Process(target=train, args=(sl, "process1"))
p2 = Process(target=debug3d, args=(sl, "process2")) # I changed here
p1.start()
p2.start()
p1.join()
p2.join()
I can't figure out the difference between two.
Thanks for your help in advance.
I have a program:
from multiprocessing import Process
import time
def plus():
for i in range(10):
print("+")
time.sleep(1)
def star():
for i in range(10):
print("%")
time.sleep(1)
if __name__ == '__main__':
p1=Process(target=plus)
p1.start()
p2=Process(target=star)
p2.start()
p1.join()
p2.join()
print('FINISH')
the output is more or less the same:
+&+&+&+&+&+&+&+&+&+& FINISH
I am trying to achieve the same passing object method into Process as follows:
import time
class Plus:
def run(self):
for i in range(10):
print("+")
time.sleep(1)
import time
class Star:
def run(self):
for i in range(10):
print("&")
time.sleep(1)
from Plus import Plus
from Star import Star
from multiprocessing import Process
class ThreadsCreation:
def run(self):
if __name__ == '__main__':
p = Plus()
g = Star()
process1 = Process(target=p.run())
process2 = Process(target=g.run())
process1.start()
process1.join()
process2.start()
process2.join()
print('FINISH')
ThreadsCreation().run()
In the second approach the output is always:
++++++++++&&&&&&&&&&FINISH
How to achieve the output of the first example with the object approach from the second one?
Does Windows support multithreading.pipes()? If yes, then what is wrong with this code? Do I need to be using reduction? The code hangs on p2.recv() and I get a RuntimeError when run from the command line.
import multiprocessing
def ProcessCreator(pipe):
pipe.send("hello from other process")
p1, p2 = multiprocessing.Pipe()
proc = multiprocessing.Process(target = ProcessCreator, args = (p2,))
proc.start()
print p1.recv()
if __name__ == "__main__":
multiprocessing.freeze_support()
You need put pipe code into if __name__ == '__main__' part.(Why?) And change p2.recv to p1.recv
import multiprocessing
def ProcessCreator(pipe):
pipe.send("hello from other process")
if __name__ == "__main__":
multiprocessing.freeze_support()
p1, p2 = multiprocessing.Pipe()
proc = multiprocessing.Process(target = ProcessCreator, args = (p2,))
proc.start()
print p1.recv()