Hello, We started experiencing slowness with atomic updates in Solr after upgrading from 7.7.2 to 8.11.1. Running several tests revealed the slowness to be in RealTimeGet's SolrIndexSearcher.getFirstMatch() call which eventually calls Lucene's SegmentTermsEnum.seekExact()..
In the benchmarks I ran, 8.11.1 is about 10x slower than 7.7.2. After discussion on the Solr mailing list I created the below JIRA: https://issues.apache.org/jira/browse/SOLR-16838 The thread dumps collected show a lot of threads stuck in the FST.findTargetArc() method. Testing environment details: Environment details: - Java 11 on Windows server - Xms1536m Xmx3072m - Indexing client code running 15 parallel threads indexing in batches of 1000 on a standalone core. - using SimpleFSDirectoryFactory (since Mmap doesn't quite work well on Windows for our index sizes which commonly run north of 1 TB) https://drive.google.com/drive/folders/1q2DPNTYQEU6fi3NeXIKJhaoq3KPnms0h?usp=sharing Is there a known issue with slowness with TermsEnum.seekExact() in Lucene 8.x ? Thanks, Rahul
