python - 为什么这段代码不能在并行 python 中工作

Question

我尝试像这样使用 pp(Parallel Python):

import glob
import subprocess
import pp


def run(cmd): 
    print cmd
    subprocess.call(cmd, shell=True) 

job_server = pp.Server()
job_server.set_ncpus(8)
jobs = []
for a_file in glob.glob("./*"): 
    cmd = "ls" 
    jobs.append(job_server.submit(run, (cmd,))) 
for j in jobs: 
    j()  

但是遇到这样的错误，subprocess.call不是全局名称。

An error has occured during the function execution
Traceback (most recent call last):
  File "/Library/Python/2.7/site-packages/pp-1.6.1-py2.7.egg/ppworker.py", line 90, in run
    __result = __f(*__args)
  File "<string>", line 3, in run
NameError: global name 'subprocess' is not defined

我已经导入了子流程，为什么这里不能使用？

根据abarnert的建议，我将代码更改为:

import glob
import pp
def run(cmd): 
    print cmd
    subprocess.call(cmd, shell=True) 
job_server = pp.Server()
job_server.set_ncpus(8)
jobs = []
for a_file in glob.glob("./*"): 
    cmd = "ls" 
    jobs.append(job_server.submit(run, (cmd,),modules=("subprocess",))) 
for j in jobs: 
    j()  

但它仍然不起作用，它提示如下:

Traceback (most recent call last):
  File "/usr/lib/python2.6/threading.py", line 532, in __bootstrap_inner
   self.run()
  File "/usr/lib/python2.6/threading.py", line 484, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/usr/local/lib/python2.6/dist-packages/pp-1.6.1-py2.6.egg/pp.py", line 721, in _run_local
    job.finalize(sresult)
UnboundLocalError: local variable 'sresult' referenced before assignment

Answer 1

文档很好地解释了这一点，每个示例都向您展示了如何处理它。

提交方法的参数之一是“模块 - 带有要导入的模块名称的元组”。您希望在提交的作业中使用的任何模块都必须在此处列出。

所以，你可以这样做:

jobs.append(job_server.submit(run, (cmd,), (), ('subprocess',)))

或者这个:

jobs.append(job_server.submit(run, (cmd,), modules=('subprocess',)))