It would be useful to see the current index heap usage (https://issues.apache.org/jira/browse/LUCENE-5197) by lucene in the LukeRequestHandler.
Add Lucene index heap size usage in the Solr admin UI
Initial patch that adds the attribute indexHeapUsageBytes to LukeRequestHandler
If any leaf is not a SegmentReader, i would just return -1 immediately (i think this is just adding an "else").
This would be consistent with other index statistics that sometimes arent supported.
Return -1 when any of the readers are not SegmentReader
Commit 1523442 from Robert Muir in branch 'dev/trunk'
[ https://svn.apache.org/r1523442 ]
SOLR-5237: add lucene index heap usage to luke request handler
Commit 1523443 from Robert Muir in branch 'dev/branches/branch_4x'
[ https://svn.apache.org/r1523443 ]
Maybe you want to open an issue to add this to the Admin UI?