Why does my parallel code generate an error?

Question

Issue 1: When sys.stdout.write is not wrapped in a separate function, the code below fails.

Issue 2: When ssys.stdout.write is wrapped in a separate function, the code prints spaces between each letter.

Code (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()

Trace:

$ ./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

Code (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()

Trace:

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

Answer 1

For the first part, pp wasn't designed to handle built-ins as arguments to submit . The second problem is more complicated. Before pp calls the submitted function, it redirects stdout and stderr to a StringIO object. On completing the task, it prints the value from the StringIO object with

print sout,

This means that it appends a space the contents of sout before printing it. To get around this, don't have your functions use sys.stdout directly, but print either to a file or a queue you manage and handle the printing of in a better way.