There are some complaints on support desk about CURLMOPT_MAX_HOST_CONNECTIONS being undefined.
We should check if curl is new enough to support that, and only set it if it is. If whatever that is is critical we should check it during environment checks in the installer.
Introduced in T232128: Make MultiHttpClient use CURLMOPT_MAX_HOST_CONNECTIONS and reuse connections (check the linked Gerrit patch in there for the code changes that were introduced).
Code in mediawiki/core repository is the line
curl_multi_setopt( $this->cmh, CURLMOPT_MAX_HOST_CONNECTIONS, (int)$maxHostConns );
in the file /includes/libs/http/MultiHttpClient.php.
Upstream docs at https://curl.haxx.se/libcurl/c/CURLMOPT_MAX_HOST_CONNECTIONS.html says that this was introduced in curl version 7.30.0.
https://www.php.net/manual/en/function.curl-version.php explains how to check the curl version in PHP.
Hence adding good first task.
Change 644639 had a related patch set uploaded (by Reedy; owner: Reedy):
[mediawiki/core@master] Make use of CURLMOPT_MAX_HOST_CONNECTIONS conditional on having curl >= 7.30.0
Change 644639 merged by jenkins-bot:
[mediawiki/core@master] Make use of CURLMOPT_MAX_HOST_CONNECTIONS conditional on having curl >= 7.30.0
Change 654858 had a related patch set uploaded (by Reedy; owner: Reedy):
[mediawiki/core@REL1_35] Make use of CURLMOPT_MAX_HOST_CONNECTIONS conditional on having curl >= 7.30.0
Change 654858 merged by jenkins-bot:
[mediawiki/core@REL1_35] Make use of CURLMOPT_MAX_HOST_CONNECTIONS conditional on having curl >= 7.30.0