Merged revisions 81652 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

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  r81652 | antoine.pitrou | 2010-06-02 19:08:47 +0200 (mer., 02 juin 2010) | 4 lines

  Issue #8873: add a documentation note about possible performance issues with the
  default of unbuffered IO in subprocess.Popen.
........

Doc/library/subprocess.rst

@@ -89,6 +89,12 @@ This module defines one class called :class:`Popen`:
    size.  A negative *bufsize* means to use the system default, which usually means
    fully buffered.  The default value for *bufsize* is :const:`0` (unbuffered).
 
+   .. note::
+
+      If you experience performance issues, it is recommended that you try to
+      enable buffering by setting *bufsize* to either -1 or a large enough
+      positive value (such as 4096).
+
    The *executable* argument specifies the program to execute. It is very seldom
    needed: Usually, the program to execute is defined by the *args* argument. If
    ``shell=True``, the *executable* argument specifies which shell to use. On Unix,