curl_easy_pause inefficiency before version 7.32.0

[Ankur deDev]

Hi,
I filed a bug report on red hat bugzilla regarding the curl_easy_pause inefficiency as described in https://curl.haxx.se/libcurl/c/curl_easy_pause.html <https://curl.haxx.se/libcurl/c/curl_easy_pause.html> page:https://bugzilla.redhat.com/show_bug.cgi?id=1563130 <https://bugzilla.redhat.com/show_bug.cgi?id=1563130>
It seems that this has been fixed in this commit: https://github.com/curl/curl/commit/b5478a0e033e70478f1c935719bf2e29fda02526 <https://github.com/curl/curl/commit/b5478a0e033e70478f1c935719bf2e29fda02526>But the assigned person is concerned that pushing the bug fix might introduce an observable change in behavior likely to trigger bugs in third party code. Maybe you could advise on this?
Also, is there a possible workaround with a limited performance impact within version 7.29.0 (the one mentioned on the curl_easy_pause.html page of calling curl_multi_socket_all is said to have "a rather hefty performance penalty")?
Thanks

[Daniel Stenberg]

On Fri, 6 Apr 2018, Ankur deDev wrote:

(First, this is a libcurl issue so I'm CC'ing my response to curl-library,
which is the list where this discussion belongs. curl-users is for the curl
tool.)

Post by Ankur deDev
I filed a bug report on red hat bugzilla regarding the curl_easy_pause
inefficiency

...
Let me also emphasize the date of that fix: July 23, 2013.

Post by Ankur deDev
the assigned person is concerned that pushing the bug fix might introduce an
observable change in behavior likely to trigger bugs in third party code.
Maybe you could advise on this?

Sure: upgrade to a modern libcurl version. You'll get that fix - and thousands
of others.

I can't really have an opinion on the sensibility of someone backporting that
fix into 7.29.0 since A) I wouldn't the be one to do it and B) I wouldn't be
the one who would have to support it afterwards.

There's always the option of doing it yourself, as then you get to both do the
work yourself and keep all the pieces in case it breaks badly.

Post by Ankur deDev
is there a possible workaround with a limited performance impact within
version 7.29.0 (the one mentioned on the curl_easy_pause.html page of
calling curl_multi_socket_all is said to have "a rather hefty performance
penalty")?

That's the work-around. The exact penality for doing like that is of course
highly dependent on your specific situation. I don't think you'll find many
people around here interested in researching this ancient problem much deeper.