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Re: libCurl does not send data using multi interface on high latency connections

From: Daniel Stenberg via curl-library <>
Date: Fri, 14 Sep 2018 00:39:40 +0200 (CEST)

On Thu, 13 Sep 2018, Nicols Bagnasco wrote:

> I downloaded and tested both examples hiperfifo and ephiperfifo to see
> if there are differences in the way they handle the CURL_POLL_OUT
> event and I found that both examples suffers from the same problem as
> well.

Here's what I tried:

1. current libcurl dev version
2. build hiperfifo with libevent 2.0.21
3. added a 100ms delay with tc, making ping "localhost" take 200ms
4. invoke hiperfifo
5. add a URL that requests a 4KB file from localhost
6. repeat step 5 20 times

I can't spot any problems with this!

I also tried to run the test suite event-based ("./ -e") with the
added delay still enabled for localhost but I spotted no problems there

Are you usoing plain HTTP urls or what schemes do you test with?

> But the thing is I am starting to think that the issue is inside libCurl,
> because the frontier of 100 ms seems pretty arbitrary to me, and because now
> there are 3 examples were the same problems occurs.

I can't think of a single thing inside libcurl that has a 100ms timeout or
expiry of anything!

I think you should consider trying with the latest curl release first before
you spend a lot of time. Maybe you're seeing a problem we already fixed?


Received on 2018-09-14