问题
I have two open file objects, dest
and src
. File object dest
is opened for writing, with the seek position placed at some offset within the file, and file object src
is opened for reading. What I need to do is simply read from the current position in src
to EOF and transfer the contents to dest
as quickly as possible.
If I were programming in Java, I could utilize the FileChannel#transferTo() method to perform zero-copy file I/O.
Does Python also support zero-copy?
回答1:
Since version 3.3, Python has os.sendfile, which interfaces to various Unix variants' sendfile(2)
zero-copy I/O interfaces. It operates on file descriptors, not general file-like objects. For older Pythons, there's py-sendfile.
回答2:
Since Python 3.8, you can use shutil.copyfile (and others from shutil
) which will internally use zero-copy if possible, such as os.sendfile
, and if not possible, fall back to a simple read-write loop.
See the shutil docs for details. Or issue 33671 (Efficient zero-copy for shutil.copy* functions (Linux, OSX and Win)). And the corresponding (merged) pull request.
You might also be interested in copy-on-write support or server-side copy support. See here, here. The os.copy_file_range (since Python 3.8) would do that. See issue 37159 (Use copy_file_range() in shutil.copyfile()) (maybe Python 3.9 or 3.10).
来源:https://stackoverflow.com/questions/7456181/does-python-support-zero-copy-i-o