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一旦进程被连接,一个multiprocessing.Process
产生的进程消耗的内存是否会被释放?python多重处理的内存使用情况
我心目中的情况大致是这样的:
from multiprocessing import Process
from multiprocessing import Queue
import time
import os
def main():
tasks = Queue()
for task in [1, 18, 1, 2, 5, 2]:
tasks.put(task)
num_proc = 3 # this many workers @ each point in time
procs = []
for j in range(num_proc):
p = Process(target = run_q, args = (tasks,))
procs.append(p)
p.start()
# joines a worker once he's done
while procs:
for p in procs:
if not p.is_alive():
p.join() # what happens to the memory allocated by run()?
procs.remove(p)
print p, len(procs)
time.sleep(1)
def run_q(task_q):
while not task_q.empty(): # while's stuff to do, keep working
task = task_q.get()
run(task)
def run(x): # do real work, allocates memory
print x, os.getpid()
time.sleep(3*x)
if __name__ == "__main__":
main()
在实际的代码中,tasks
长度远远大于CPU内核的数量,每个task
是轻量级的,不同的任务需要很大的不同CPU时间(几分钟到几天)和大量不同的内存(从花生到几个GB)。所有这些内存都位于run
的本地,因此无需共享它---所以问题在于一旦run
返回,和/或一旦进程加入后,它是否会被释放。