Question

问题1：如果sys.stdout.write未包含在单独的函数中，则以下代码将失败。

问题2：当ssys.stdout.write包装在单独的函数中时，代码会在每个字母之间打印空格。

代码（v1）：

#!/usr/bin/env python

import pp
import sys

def main():
    server = pp.Server()

    for c in "Hello World!\n":
        server.submit(sys.stdout.write, (c,), (), ("sys",))()

if __name__=="__main__":
    main()

跟踪：

$ ./parhello.py
Traceback (most recent call last):
  File "./parhello.py", line 15, in <module>
    main()
  File "./parhello.py", line 12, in main
    server.submit(write, (c,), (), ("sys",))()
  File "/Library/Python/2.7/site-packages/pp.py", line 461, in submit
    sfunc = self.__dumpsfunc((func, ) + depfuncs, modules)
  File "/Library/Python/2.7/site-packages/pp.py", line 639, in __dumpsfunc
    sources = [self.__get_source(func) for func in funcs]
  File "/Library/Python/2.7/site-packages/pp.py", line 706, in __get_source
    sourcelines = inspect.getsourcelines(func)[0]
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/inspect.py", line 688, in getsourcelines
    lines, lnum = findsource(object)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/inspect.py", line 527, in findsource
    file = getsourcefile(object)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/inspect.py", line 446, in getsourcefile
    filename = getfile(object)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/inspect.py", line 422, in getfile
    'function, traceback, frame, or code object'.format(object))
TypeError: <built-in method write of file object at 0x1002811e0> is not a module, class, method, function, traceback, frame, or code object
make: *** [test] Error 1

代码（v2）：

#!/usr/bin/env python

import pp
import sys

def hello(c):
    sys.stdout.write(c)

def main():
    server = pp.Server()

    for c in "Hello World!\n":
        server.submit(hello, (c,), (), ("sys",))()

if __name__=="__main__":
    main()

跟踪：

$ ./parhello.py
H e l l o   W o r l d !

Answer 1

对于第一部分，pp并非旨在将内置函数作为submit的参数来处理。第二个问题更复杂。在pp调用提交的函数之前，它会将stdout和stderr重定向到StringIO对象。完成任务后，它将使用

打印StringIO对象中的值

print sout,

这意味着在打印之前，它会在sout的内容后附加一个空格。要解决这个问题，请不要让您的函数直接使用sys.stdout，而是打印到您管理的文件或队列，并以更好的方式处理打印。

为什么我的并行代码会产生错误？

1 个答案: