: The main issue we found was a lot of millions of LazyField instances, : taking ~2GB of memory, even though queries request about 10 small fields : only.
which version of Solr are you using? there was a really bad bug with lazyFieldLoading fixed in Solr 4.2.1 (SOLR-4589) : We've found that LazyDocument creates a LazyField object for every item in : a multivalued field, even if do not want this field. right, that's exactly how lazyFieldLoading is designed to work -- instead of loading the full field values into ram, only a small LazyField object is loaded in it's place and that LazyField only fetches the underlying data if/when it's requested. If the LazyField instances weren't created as placeholders, subsequent requests for the document that *might* request additional fields (beyond the "10 small fields" that were requested the first time) would have no way of knowing if/when those additional fields existed to be able to fetch them from the index. : In our case, documentCache was configured to 32000. There are 2 cores per : node, so 64000 LazyDocument instances are in memory. This is pretty big : number, and we'll reduce it. FWIW: Even at 1/10 that size, that seems like a ridiculously large documentCache to me. -Hoss
