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Re: Poor HTTP POST upload performance

From: Dan Fandrich <>
Date: Thu, 16 Apr 2015 09:12:42 +0200

On Wed, Apr 15, 2015 at 08:41:16PM +0200, Daniel Stenberg wrote:
> On Mon, 13 Apr 2015, Bryan Christ wrote:
> >I've been trying to figure out why http POST uploads are so slow with
> >libcurl. Upload speeds continually perform at about 1/10th of the
> >expected performance (or less). Many users have reported this behavior on
> >our forum. I suspect it has a lot to do with CURL_MAX_WRITE_SIZE being set
> >to 16k.
> Why suspect? Rebuild a test version with it set to 1024KB and see what
> difference it makes (if any) and remove any doubts.
> We have settled on the current size only because we have not seen any
> evidence of a larger buffer giving any notable difference (in most cases -
> not counting SFTP).
> We are always open to reevaluating our former decisions, but we prefer doing
> so based on data and evidence to back up the ideas!

A selectable buffer size is 1.6 in the TODO list, where it's been for a very
long time now. It wouldn't be that difficult a change, it's just that no-one
has ever stepped up with a patch.

>>> Dan
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Received on 2015-04-16