Recently a method was implemented in Lucene to estimate the index heap usage
(https://issues.apache.org/jira/browse/LUCENE-5197). It would be very helpful to display this information in the admin UI.
Add Lucene Index heap usage to LukeRequestHandler
Commit 1530170 from Robert Muir in branch 'dev/branches/branch_4x'
[ https://svn.apache.org/r1530170 ]
SOLR-5226: add lucene index heap usage to the solr admin UI
Commit 1530169 from Robert Muir in branch 'dev/trunk'
[ https://svn.apache.org/r1530169 ]
Attached a patch to display the luceneIndexHeapUsage in the index dashboard, using the newly added attribute in the lukeRequestHandler (https://issues.apache.org/jira/browse/SOLR-5237)