[英]Python Multiprocessing Pool not launching jobs
這是Python 2.7。 我已經成功嘗試了文檔代碼:
from multiprocessing import Pool
def f(x):
return x*x
if __name__ == '__main__':
pool = Pool(processes=4) # start 4 worker processes
result = pool.apply_async(f, [10]) # evaluate "f(10)" asynchronously
print result.get(timeout=1) # prints "100" unless your computer is *very* slow
print pool.map(f, range(10)) # prints "[0, 1, 4,..., 81]"
然后,我自己開發了一個非常簡單的示例,但是沒有成功:
import multiprocessing
def run_test_n(n):
print 'inside test %d' % n
with open('test%d.log' % n, 'w') as f:
f.write('test %d ok\n' % n)
def runtests(ntests, nprocs):
pool = multiprocessing.Pool(processes = nprocs)
print 'runnning %d tests' % ntests
print 'over %d procs' % nprocs
tasks = range(1, ntests + 1)
results = [pool.apply_async(run_test_n, t) for t in tasks]
for r in results:
r.wait()
if __name__ == '__main__':
runtests(5,5)
在此示例中,不創建任何文件,也不打印“ inside test ...”字符串。
好像從未調用過run_test_n(實際上從未調用過)。 為什么?
您的results = [pool.apply_async(run_test_n, t) for t in tasks]
錯誤results = [pool.apply_async(run_test_n, t) for t in tasks]
; 正確的形式是results = [pool.apply_async(run_test_n, (t, )) for t in tasks]
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