Search based on user profiles in Drupal 7 I want to develop user matching feature on website. A user will search by giving some search criteria (like we give search criteria in dating / real estate website to filter out search results), and system after, filtering out, will return the users matching that search criteria. 

How can it be accomplish in Drupal 7 ? Is there any module or combination to modules to achieve that goal ? Thanks in advance.
Searching with Drupal core is not very performative because you are doing search queries in a mysql database.

Apache Solr is much more performative and includes a much greater feature set for searching Drupal content: http://drupal.org/project/apachesolr

If you want to limit search results just to users you can use the solr module above plus Facet API http://drupal.org/project/facetapi and only expose the facets for the content authors. You can also create a view using Solr Views that will return the author in the search results.