From c395545a4ab4b4760c0472af74f526f405389864 Mon Sep 17 00:00:00 2001 From: Antoine Pitrou Date: Wed, 2 Jun 2010 17:08:47 +0000 Subject: [PATCH] Issue #8873: add a documentation note about possible performance issues with the default of unbuffered IO in subprocess.Popen. --- Doc/library/subprocess.rst | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/Doc/library/subprocess.rst b/Doc/library/subprocess.rst index 19a8b6b8260..b5e769cab59 100644 --- a/Doc/library/subprocess.rst +++ b/Doc/library/subprocess.rst @@ -94,6 +94,12 @@ 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,