import timefrom multiprocessing import Processdef worker(): time.sleep(2) print("Working")def runInParallel(*fns): proc = [] for fn in fns: p = Process(target=fn) p.start() proc.append(p) for p in proc: p.join()if __name__ == '__main__': start = time.time() runInParallel(worker, worker, worker, worker) print("Total time taken: ", time.time()-start)但是，如果我添加參數(shù)，worker()它就不再并行運(yùn)行。import timefrom multiprocessing import Processdef worker(ii): time.sleep(ii) print("Working")def runInParallel(*fns): proc = [] for fn in fns: p = Process(target=fn) p.start() proc.append(p) for p in proc: p.join()if __name__ == '__main__': start = time.time() runInParallel(worker(2), worker(2), worker(2), worker(2)) print("Total time taken: ", time.time()-start)原因可能是什么？
4 回答
精慕HU
TA貢獻(xiàn)1845條經(jīng)驗(yàn) 獲得超8個(gè)贊
您應(yīng)該修改runInParallel以進(jìn)行可迭代的解包。
import time
from multiprocessing import Process
def worker(ii):
time.sleep(ii)
print("Working")
def runInParallel(*fns):
proc = []
for fn in fns:
func, *args = fn
p = Process(target=func, args=args)
p.start()
proc.append(p)
for p in proc:
p.join()
if __name__ == '__main__':
start = time.time()
runInParallel((worker, 2), (worker, 3), (worker, 5), (worker, 2))
print("Total time taken: ", time.time()-start)
慕桂英546537
TA貢獻(xiàn)1848條經(jīng)驗(yàn) 獲得超10個(gè)贊
worker這是因?yàn)楹椭g的差異worker()。前者是函數(shù)，后者是函數(shù)調(diào)用。線路上發(fā)生的情況runInParallel(worker(2), worker(2), worker(2), worker(2))是，在開始執(zhí)行之前，所有四個(gè)調(diào)用runInParallel都已運(yùn)行。如果你print(fns)在開頭添加一個(gè)，runInParallel你會(huì)看到一些不同。
快速解決：
def worker_caller():
worker(2)
和：
runInParallel(worker_caller, worker_caller, worker_caller, worker_caller)
這不是很方便，但主要是為了顯示問題所在。問題不在函數(shù)中worker。問題在于您混淆了傳遞函數(shù)和傳遞函數(shù)調(diào)用。如果您將第一個(gè)版本更改為：
runInParallel(worker(), worker(), worker(), worker())
那么你會(huì)遇到完全相同的問題。
但你可以這樣做：
runInParallel(lambda:worker(2), lambda: worker(2), lambda: worker(2), lambda: worker(2))
Lambda 非常有用。這是另一個(gè)版本：
a = lambda:worker(2)
b = lambda:worker(4)
c = lambda:worker(3)
d = lambda:worker(1)
runInParallel(a, b, c, d)
ibeautiful
TA貢獻(xiàn)1993條經(jīng)驗(yàn) 獲得超6個(gè)贊
要傳遞參數(shù)，您需要將它們傳遞給Process構(gòu)造函數(shù)：
p = Process(target=fn, args=(arg1,))
楊__羊羊
TA貢獻(xiàn)1943條經(jīng)驗(yàn) 獲得超7個(gè)贊
Process 構(gòu)造函數(shù)接受 args 和 kwargs 參數(shù)，然后在執(zhí)行時(shí)將這些參數(shù)傳遞給進(jìn)程。文檔對此非常清楚。
所以你的代碼應(yīng)該修改如下：
def worker(ii):
time.sleep(ii)
print("Working")
def runInParallel(*fns):
proc = []
for fn in fns:
p = Process(target=fn, args=(2,))
p.start()
proc.append(p)
for p in proc:
p.join()
if __name__ == '__main__':
start = time.time()
runInParallel(worker, worker, worker, worker)
print("Total time taken: ", time.time()-start)
當(dāng)然，每個(gè)進(jìn)程的參數(shù)可能不同，您需要安排將正確的參數(shù)傳遞給 args（或關(guān)鍵字參數(shù)的 kwargs）中的每個(gè)進(jìn)程。這可以通過傳遞元組來實(shí)現(xiàn)，例如runInParallel((worker,2), (worker,3), (worker,5), (worker,1)，然后處理內(nèi)部的元組runInParallel。
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