On Fri, 10 Dec 2021, Dmitry Karpov via curl-library wrote:
While parallel query requests in c-ares are not there yet, I am wondering if it is possible to control DNS timeout or expose such control via curl handle options in the future? I noticed that libcurl always uses the default c-ares timeout value, which is 5s, and happy eyeball DNS timeout also relies on that value by hard coding it in the HAPPY_EYEBALLS_DNS_TIMEOUT constant, but in some cases, 5s may be a too long wait before switching to a different name server.
I agree that 5 seconds is a very long time that should probably be lowered, but that timeout logic in curl is also only used when an old c-ares version is used so maybe the effort is better spent elsewhere anyway?
I am wondering, if you think that doing such changes will be a very risky change even as a short-term solution?
I don't think it will be particularly risky, no. I also think we should be able to lower the default timeout somewhat. I do however think that this is mostly a problem for c-ares itself to handle. I mean, we don't set any timeout values at all when we use libc's resolver functions...
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