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Re: Curl/LibCurl compiled on OS X without --disable-ipv6 is really slow

From: Daniel Stenberg <>
Date: Fri, 19 Dec 2003 14:11:59 +0100 (CET)

On Fri, 19 Dec 2003, Jacob Swed wrote:

> The library version being used is 7.11.0-20031217. Compiled under OS X
> 10.2.8.
> We have not investigated the why, but have determined that if curl/libcurl
> is complied on OS X without the --disable-ipv6 option performance is
> severely and noticeably degraded. curl/libcurl takes an extremely long time
> resolving the host or host IP. Compiling with the --disable-ipv6 option
> alleviates the delays entirely. Incidentally, this occurs when run on
> vanilla installations of OS 10.1, 10.2 and 10.3.

The difference in name lookups between ipv6 enabled and disabled, is the use
of getaddrinfo (for ipv6-enabled) or gethostbyname (for ipv6-disabled).

I fail to see what libcurl can do to affect the name lookup speeds, other than
leave it to the system libraries.

Some linux installations are known to perform very slow lookups with
a ipv6-enabled kernel but without ipv6 support really enabled, which libcurl
tries to detect and adjust to. Perhaps there's something similar in Mac OS X

    Daniel Stenberg -- --
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Received on 2003-12-19