Re: [Libguestfs] [PATCH nbdkit] curl: Try to share as much as possible between handles in the pool

On Wed, Feb 22, 2023 at 04:52:35PM +0100, Laszlo Ersek wrote: ... > Seems sane to me in general, except for the fact that the documentation > at <https://curl.se/libcurl/c/CURLSHOPT_SHARE.html> writes: > > """ > CURL_LOCK_DATA_CONNECT > > Put the connection cache in the share object and make all easy handles > using this share object share the connection cache. > > Note that due to a known bug, it is not safe to share connections this > way between multiple concurrent threads. [...] > """ > > Ugh, what? If it's not safe to share the connection cache between > threads, then CURL_LOCK_DATA_CONNECT is effectively unusable, and no > connection pooling can be done. How does that *not* make this whole curl > facility useless? > > The facility in general looks super weird; what sense does it make *not* > to share some particular CURL_LOCK_DATA_xxx? I can only conclude this cannot be true. Daniel Stenberg wrote this code which definitely uses threads: https://gist.github.com/bagder/7eccf74f8b6d70b5abefeb7f288dba9b Also I did a lot of testing and didn't hit any obvious threading bugs.

Nevertheless I'm not planning to integrate this patch any time soon.