Global variables are not shared between processes.
You need to use multiprocessing.Manager.list
:
from multiprocessing import Process, Manager
def dothing(L, i): # the managed list `L` passed explicitly.
L.append("anything")
if __name__ == "__main__":
with Manager() as manager:
L = manager.list() # <-- can be shared between processes.
processes = []
for i in range(5):
p = Process(target=dothing, args=(L,i)) # Passing the list
p.start()
processes.append(p)
for p in processes:
p.join()
print L
See Sharing state between processes¶ (Server process part).