I am using the py-lmdb python binding for LMDB. I am confused what the meaning of the hyphens is in the "reader lock table" returned by the function mdb_reader_list for LMDB (or env.readers for the py-lmdb binding).
My best guess is the hyphens represent a committed transaction. In my program, I am pretty certain that whenever I open a reader, I will commit it before opening a second one. In particular, whenever I create a new reader, either the reader lock table is empty, or every row (besides the header) of the reader lock table contains a hyphen. However, the reader lock table will fill up with these hyphen rows, eventually raising a MDB_READERS_FULL error (lmdb.ReadersFullError for the py-lmdb binding). I genuinely have no idea why this happens.