Re: infinite "easy_transfer function" wait loop

From: Henrik Holst via curl-library <curl-library_at_lists.haxx.se>
Date: Tue, 8 Feb 2022 16:07:26 +0100

I just wanted to say that you are not alone with this problem, I have seen
this happen as well. I have an application that downloads an external link
once per second 24x7 and on some seldom but random occasion (perhaps 2-3
times per year) it gets stuck in curl_multi_socket_action().

So far I have not been able to catch it in the act since it have happened
at times where I have been away and my colleges have simply restarted the
service (so as to not have any outage). My problem is that it happens so
rare that I cannot just run it with a debugger so my only hope at this
point is to catch it in the act and connect a debugger live to it when it
happens the next time. You seem to run on Windows and I have zero knowledge
if one can attach debuggers or have the equivalent of ltrace/strace on a
running application there like you can on Linux.

/HH

Den tis 8 feb. 2022 kl 08:32 skrev Lilia Boneva via curl-library <
curl-library_at_lists.haxx.se>:

>
> Hello again and thank you for the help.
> Like Mr. Ray Satiro noticed, It seems I was not set google drive link
> properly. Now should be OK (
> https://drive.google.com/file/d/1kdMSBS9fZPBW4WoMJ4qgHIeB01h46d4V/view?usp=sharing).
> Also thank you for links and winsock info.
>
> I will try making working code to share (now not so easy because the
> secure requests use private data).
> I will also try release version (like Mr. Dmitry Karpov suggested) and
> other curl versions, because 7.77 for example runs >5 days before infinite
> loop (7.81 less than a day)
> Thank you for suggesting ideas toward solutionHave a nice day
>
>
> PS1:
> by Ray Satiro:"The file you linked to is inaccessible. HTTP/2 will be
> harder to debug
>
> so stay with 1.1 for now. There might be 3rd party Windows sockets
>
> libraries but since nobody uses them with curl they might cause other
>
> problems. Keep using winsock.
>
>
>
> There is not enough information here to say this is a curl problem. Can
>
> you show us the code you are using? Do you have a minimal self contained
>
> example that can be used to reproduce on a public website like
>
> httpbin.org for example? Please review the documentation for the multi
>
> interface [1] and multi- prefixed examples [2].
>
>
>
>
>
> [1]: https://curl.se/libcurl/c/libcurl-multi.html
>
> [2]: https://curl.se/libcurl/c/example.html
>
> "
> PS2:by Dmitry Karpov"I assume that you made a "Debug" build and ran your
> program under MSVC debugger for 20hrs, right?
>
> Do you see the same problem for the "release" build (or for "debug" build)
> when it is not running under MSVC debugger?
>
>
>
> I have seen issues with MSVC debugger in the past, so the issue you
> observed may be a debugger issue (when it has been running for too long)
> rather than curl's one.
>
>
>
> I would put some debugging "printf" messages into your app to detect the
> infinite loop but run it as the production "release" build not under
> MSVC debugger to confirm that it is not a debugger issue.
>
>
>
> And if you still see the "infinite loop" issue without running under
> debugger, then, as some folks already mentioned , could you please
> provide some sample or "skeleton" code like what you are using in your
> app to illustrate where the "infinite loop" happens?
>
>
>
> Thanks,
>
> Dmitry Karpov"
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Received on 2022-02-08