[Python-Dev] how to debug httplib slowness (original) (raw)

Guido van Rossum guido at python.org
Fri Sep 4 20:22:21 CEST 2009

On Fri, Sep 4, 2009 at 4:28 AM, Simon Cross<hodgestar+pythondev at gmail.com> wrote:

On Fri, Sep 4, 2009 at 1:11 PM, Chris Withers<chris at simplistix.co.uk> wrote:

Am I right in reading this as most of the time is being spent in httplib's HTTPResponse.readchunked and none of the methods it calls?

If so, is there a better way that a bunch of print statements to find where in that method the time is being spent? Well, since the source for readchunked includes the comment  # XXX This accumulates chunks by repeated string concatenation,  # which is not efficient as the number or size of chunks gets big. you might gain some speed improvement with minimal effort by gathering the read data chunks into a list and then returning "".join(chunks) at the end.

+1 on trying this. Constructing a 116MB string by concatenating 1KB buffers surely must take forever. (116MB divided by 85125 recv() calls give 1365 byte per chunk, which is awful.) The HTTP/1.0 business looks like a red herring.

Also agreed that this is an embarrassment.

-- --Guido van Rossum (home page: http://www.python.org/~guido/)

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