Question

http://www.greenteapress.com/thinkpython/html/book015.html#toc159“rel=“nofollow noreferer”>a section in ,这大概是准确的书:,

A common use of pipes is to read a compressed file incrementally; that is, without uncompressing the whole thing at once. The following function takes the name of a compressed file as a parameter and returns a pipe that uses gunzip to decompress the contents:
 def open_gunzip(filename):
     cmd =  gunzip -c   + filename
     fp = os.popen(cmd)
     return fp
If you read lines from fp one at a time, you never have to store the uncompressed file in memory or on disk.

也许我只是解释这一错误,但我看不到这一点是可能的。灰 Python可能有任何手段通过淡化结果来铺平枪道? 我假定,在继续生产线之前,在一行产出之前,会把枪弹推向碎块,因此,有些缓冲必须抓住所有这些东西(无论是在杰里德语译员内部还是从书记处,无论是在记忆中还是在磁盘上),也就是说,未经压缩的档案正全部储存在,。

Answer 1

你的假设是错误的。枪手不一定要看到整个卷宗去除。阅读单页文档格式。有一个目录,各部分各部分各有余。

它有可能将档案编成零件。

“未经压缩的档案被完全存放......”

不一定。你们为什么要重新承担这一责任,或者在你们读了。

所有低级I/O电话都可以阻挡。以枪口书写——写到管道时——当管道缓冲区满时可以阻挡。这是I/O通往管道的方式。管道I/O区。

详细检查管道的人工页。

If a process attempts to read from an empty pipe, then read(2) will
block until data is available. If a process attempts to write to a
full pipe (see below), then write(2) blocks until sufficient data has
been read from the pipe to allow the write to complete. Non-blocking
I/O is possible by using the fcntl(2) F_SETFL operation to enable the
O_NONBLOCK open file status flag.

Answer 2

This really comes from gunzip implementation, not from python. It is written in C. It probably uses fwrite() from C s stdio.h to write its output.

我使用自动产生产出缓冲,一旦填满,则在<条码>fwrite()栏上加块,直到能够写上更多的字。

Answer 3

它没有暂停<代码>gunzip,它规定,ker将停止执行<编码>gunzip<>。当它试图书写(使用<条码>write(<>>>>>>>条/代码>扫描)至充分的缓冲。这称为blocking on IO。油轮保持内部缓冲,把管道的两端连接起来,独立于任何与管道书写或阅读的过程发生的任何缓冲。

当从一个有空洞缓冲的管道中读到时,灰尘同样会受阻,也就是说,目前无任何数据来自<代码>gunzip。

管道可被视为。

友情链接