Bulk Operation

SOLR-15509 Add SparseBitSet option for faster faceting, lower memory usage, and reduced gc at scael.

SOLR-15509 Heavily reduce faceting ram usage for many cases.

SOLR-15509 Investigate if any minor tweaks can be made to improve the json output paths branch predictability.

SOLR-15509 Offer an MMapDirectoryFactory that writes with DirectIODirectory rather than FSDirectory.

SOLR-15509 Write escaped strings in SolrJSONWriter to a StringBuilder before the writer.

SOLR-15509 Optimize JavaBinCodec encode/decode performance.

SOLR-15509 Add a VirtualExecutor.

SOLR-15509 Add / Compare optional experimental MMapDirectory implementation via custom ByteBuffer lib (eg Agrona, Chronicle Bytes, ...)

SOLR-15509 Review, enhance(?), sql-connect multi-threaded SimpleFaceting impl/config

SOLR-15509 Add support for passing IndexSearcher an executor for multi-threaded multi-segment and possible future multi-threaded per segment search.

SOLR-15509 Add FastThreadLocal type design enhancement and some buffer / object reuse for reduced gc at scale.

SOLR-15509 Add off heap BitSet data structure option and ByteBuffer caching for reduced GC at scale.

SOLR-15509 Logging Performance