Hi zoglun. This does not sound like something is wrong in the code of MediaWiki (a so-called "bug"), but instead like a support request (how to change settings, questions how to do something, etc.). bugzilla.wikimedia.org is only for specific bug reports and enhancement requests.
Please use https://www.mediawiki.org/wiki/Project:Support_desk for support requests to make sure that functionality does not exist; afterwards an enhancement request can be filed in Bugzilla. Thanks!

This is quite confusing, I ask same question at the support dest and people said I should report it here: https://www.mediawiki.org/wiki/Thread:Project:Support_desk/How_to_separate_sitemap_into_series_small_file%3F

Neither Google nor Baidu(largest search engine in China) accept my sitemap due to "over maximum links limitation"

Their is a "$wgDefaultLanguageVariant = "zh-cn";" which allows me to set the default language variant while still keep the variant function. But the GenerateSitemap.php still generate three link for three exactly the same page.

The purpose of sitemaps is to allows search engine collect pages. When these engine refuse to record the links in sitemap.xml, that's a bug. Isn't it?

(In reply to zoglun from comment #2)

I ask same question at the support dest and people said I should report it here

That's very good and information which is already welcome when reporting a ticket here. :)

The phrasing of this ticket as a question makes it sound like you simply do not know if it's possible and have a support question; however the comments in the Support Desk ("I don't think you can split the sitemap up like that") make clear that it's very likely not possible currently and hence a valid feature request.

Change 290143 had a related patch set uploaded (by Nbdd0121):
Count language variant sitemap entries for url_limit

https://gerrit.wikimedia.org/r/290143

Change 609513 had a related patch set uploaded (by VulpesVulpes825; owner: VulpesVulpes825):
[mediawiki/core@master] Write language varaint link as child element rather than individual entry in sitemap

https://gerrit.wikimedia.org/r/609513

Change 609513 abandoned by VulpesVulpes825:

[mediawiki/core@master] Write language varaint link as child element rather than individual entry in sitemap

Reason:

https://gerrit.wikimedia.org/r/609513

Change 808009 had a related patch set uploaded (by PleaseStand; author: PleaseStand):

[mediawiki/core@master] generateSitemap.php: Fix a couple limit checking bugs

https://gerrit.wikimedia.org/r/808009