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Re: 10-at-a-time.c libcurl example - limitations?

From: Matthew Ford <>
Date: Tue, 20 Dec 2011 12:42:11 +0000

On 13 Dec 2011, at 08:50, Daniel Stenberg wrote:

> On Thu, 8 Dec 2011, Matthew Ford wrote:
>> Actually, I think I spoke to soon. I'm now getting results, but the performance is much slower once we reach 1024 hostnames. I have ulimit -n = 65535, and if I grep FDSize /proc/<PID>/status I get 2048 returned after we reach 1024 hostnames queried. Are there other limits I might be running in to?
> If you're still using select(), you need to do compile-time tweaks so that fd_set() and friends still work and don't access data out of boundary.
> Also, at that amount of descriptors I suspect that you may start seeing some speed penalty from using select().

Thanks for the suggestions. Actually turned out to be the way I was redirecting output that was causing the problem - I should have just let libcurl handle it and I would have been fine. Now blisteringly fast asynchronous performance from libcurl/c-ares - thanks!


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Received on 2011-12-20