[Python-Dev] Fw: SocketServer and makefile() [from comp.lang.python] (original) (raw)

Greg Stein gstein@lyra.org
Thu, 31 Aug 2000 13:04:18 -0700

On Thu, Aug 31, 2000 at 03:48:16PM -0500, Guido van Rossum wrote:

I wrote: ... > Solution? Don't use rfile for reading, but go for the socket itself. Or > revamp the two classes to forget about the socket once the files (wfile and > rfile) are created. The latter might not be possible, tho.

I was about to say that you have it backwards, and that you should only use rfile & wfile, when I realized that CGIHTTPServer.py needs this! The subprocess needs to be able to read the rest of the socket, for POST requests. So you're right.

Ooh! I hadn't considered that case. Yes: you can't transfer the contents of a FILE's buffer to the CGI, but you can pass a file descriptor (the socket).

Solution? The buffer size should be an instance or class variable. Then SocketServer can set it to buffered by default, and CGIHTTPServer can set it to unbuffered.

Seems reasonable.

> Dunno why the unbuffered reading would be slow. I'd think it would still > read large chunks at a time when you request it.

System call overhead? I had the same complaint about Windows, where apparently winsock makes you pay more of a performance penalty than Unix does in the same case.

Shouldn't be. There should still be an rfile.read(1000) in that example app (with the big transfers). That read() should be quite fast -- the buffering should have almost no effect.

So... what is the underlying problem?

[ IOW, there are two issues: the sock vs file thing; and why rfile is so darn slow; I have no insights on the latter. ]

Cheers, -g

-- Greg Stein, http://www.lyra.org/