我尝试使用Python的进程池多处理功能。
无论我如何设置块大小(在Windows 7和Ubuntu下 - 后者使用4个内核,见下文),并行线程的数量似乎保持不变。
from multiprocessing import Pool
from multiprocessing import cpu_count
import multiprocessing
import time
def f(x):
print("ready to sleep", x, multiprocessing.current_process())
time.sleep(20)
print("slept with:", x, multiprocessing.current_process())
if __name__ == '__main__':
processes = cpu_count()
print('-' * 20)
print('Utilizing %d cores' % processes)
print('-' * 20)
pool = Pool(processes)
myList = []
runner = 0
while runner < 40:
myList.append(runner)
runner += 1
print("len(myList):", len(myList))
# chunksize = int(len(myList) / processes)
# chunksize = processes
chunksize = 1
print("chunksize:", chunksize)
pool.map(f, myList, 1)
无论我使用
chunksize = int(len(myList) / processes)
,chunksize = processes
还是1
(如上面的例子),行为都是相同的。
可能自动将chunksize设置为核心数量吗?
chunksize = 1
的示例:
--------------------
Utilizing 4 cores
--------------------
len(myList): 40
chunksize: 10
ready to sleep 0 <ForkProcess(ForkPoolWorker-1, started daemon)>
ready to sleep 1 <ForkProcess(ForkPoolWorker-2, started daemon)>
ready to sleep 2 <ForkProcess(ForkPoolWorker-3, started daemon)>
ready to sleep 3 <ForkProcess(ForkPoolWorker-4, started daemon)>
slept with: 0 <ForkProcess(ForkPoolWorker-1, started daemon)>
ready to sleep 4 <ForkProcess(ForkPoolWorker-1, started daemon)>
slept with: 1 <ForkProcess(ForkPoolWorker-2, started daemon)>
ready to sleep 5 <ForkProcess(ForkPoolWorker-2, started daemon)>
slept with: 2 <ForkProcess(ForkPoolWorker-3, started daemon)>
ready to sleep 6 <ForkProcess(ForkPoolWorker-3, started daemon)>
slept with: 3 <ForkProcess(ForkPoolWorker-4, started daemon)>
ready to sleep 7 <ForkProcess(ForkPoolWorker-4, started daemon)>
slept with: 4 <ForkProcess(ForkPoolWorker-1, started daemon)>
ready to sleep 8 <ForkProcess(ForkPoolWorker-1, started daemon)>
slept with: 5 <ForkProcess(ForkPoolWorker-2, started daemon)>
ready to sleep 9 <ForkProcess(ForkPoolWorker-2, started daemon)>
slept with: 6 <ForkProcess(ForkPoolWorker-3, started daemon)>
ready to sleep 10 <ForkProcess(ForkPoolWorker-3, started daemon)>
slept with: 7 <ForkProcess(ForkPoolWorker-4, started daemon)>
ready to sleep 11 <ForkProcess(ForkPoolWorker-4, started daemon)>
slept with: 8 <ForkProcess(ForkPoolWorker-1, started daemon)>