Almonas Glamba

Row-store lock changed to fair after 2.5.0 - fairness probably could be made configurable

Hello, there a substantial throughput regression to the row-store lock switching from unfair to fair locking after 2.5.0. In org.hsqldb.persist.RowStoreAVLMemory (and RowStoreAVLDisk) the construction changed in 2.5.1 from: lock = new ReentrantReadWriteLock(); to: lock = new ReentrantReadWriteLock(true); My use case is an in-memory database (MVCC) with one writer thread and many concurrent reader sessions (originally Java 11 / Linux). After moving past 2.5.0 I saw reader throughput collapse under...