We have a SharePoint 2013 intranet portal. When I try to reset the search index it times out. Someone have asked the same question here 2013 Content Index Reset Timeout
and it seems this solution works
Basically the solution is to delete the XML files from this location ProgramData\Microsoft\SharePoint\Config and then rebuild the search index...
I haven't tried this yet... but is this the officially recommended approach to troubleshoot and fix search index reset issue?