在MINGW/MSYS Python 2.7.3上，stdout的行缓冲失败 [英] Line-buffering of stdout fails on MINGW/MSYS Python 2.7.3

问题描述

此问题通过以下简单脚本说明:

The problem is illustrated by this simple script:

import time, os, sys
sys.stdout = os.fdopen( sys.stdout.fileno(), 'w', 1 ) # line-buffer stdout
print 'before sleep'
time.sleep( 10 )
print 'after sleep'

如果行缓冲成功，则两行打印之间将有10秒的间隔.如果不是这样，则在暂停10秒后(Python启动后)，这两行几乎同时出现.也就是说，程序退出时将打印这些行.

If line-buffering is successful, then there will be a 10-sec gap between the printing of the two lines. If not, both lines will appear virtually at the same time after a 10-sec pause (once Python starts up); that is, the lines are printed when the program exits.

在Linux上，如果包含"sys.stdout"行，则在文件和屏幕上都会看到行缓冲行为.如果没有该行，我会在屏幕上看到行缓冲的行为，但在文件中却看不到.这是预期的.

On Linux, I see line-buffered behavior to both a file and to the screen if the "sys.stdout" line is included. Without that line, I see line-buffered behavior to the screen, but not to a file. This is expected.

在MSYS/MINGW环境中，如果省略"sys.stdout"行，则会看到与Linux相同的行为:行缓冲到屏幕而不是文件.

In the MSYS/MINGW environment, if I omit the "sys.stdout" line, I see the same behavior as Linux: line-buffering to the screen but not to a file.

奇怪的是，带有"sys.stdout"行，我看不到 屏幕或文件的行缓冲.我希望两者都能看到，就像在Linux中一样.

What is weird is that with the "sys.stdout" line, I don't see line-buffering to either the screen or a file. I expect to see it to both, as in Linux.

有人可以建议解决方法吗?

Can anyone suggest a workaround?

这里有更多信息:

uname -a MINGW32_NT-6.0 FOO 1.0.11(0.46/3/2)2009-05-23 19:33 i686 Msys

uname -a MINGW32_NT-6.0 FOO 1.0.11(0.46/3/2) 2009-05-23 19:33 i686 Msys

谢谢， -W.

推荐答案

我的一位同事知道答案.

One of my colleagues knew the answer.

在WIN32上不支持行缓冲.如果指定了行缓冲，它将恢复为完整缓冲.提供了无缓冲的输出，解决方法是在WIN32上使用它.我已经在简单的测试程序中对其进行了尝试，并且可以正常工作.

Line buffering is not supported on WIN32. If line buffering is specified, it reverts to full buffering. Unbuffered output is available, and the workaround is to use it on WIN32. I have tried it in my simple test program, and it works.

引用: http://msdn .microsoft.com/en-us/library/86cebhfs％28v = vs.71％29.aspx

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