python - 禁用输出缓冲

Question

Python 的解释器是否默认为 sys.stdout 启用输出缓冲？

如果答案是肯定的，那么禁用它的方法有哪些？

到目前为止的建议:

1. 使用-u命令行开关
2. 将 sys.stdout 包装在每次写入后刷新的对象中
3. 设置PYTHONUNBUFFERED环境变量
4. sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)

有没有其他方法可以在执行期间以编程方式在 sys/sys.stdout 中设置一些全局标志？

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_{如果您只想在使用print 的特定写入之后刷新，请参阅How can I flush the output of the print function? .}

Answer 1

来自 Magnus Lycka answer on a mailing list :

You can skip buffering for a whole python process using python -u or by setting the environment variable PYTHONUNBUFFERED.

You could also replace sys.stdout with some other stream like wrapper which does a flush after every call.

class Unbuffered(object):
   def __init__(self, stream):
       self.stream = stream
   def write(self, data):
       self.stream.write(data)
       self.stream.flush()
   def writelines(self, datas):
       self.stream.writelines(datas)
       self.stream.flush()
   def __getattr__(self, attr):
       return getattr(self.stream, attr)

import sys
sys.stdout = Unbuffered(sys.stdout)
print 'Hello'