Parsed test spec with 3 sessions

starting permutation: s2insert s3insert s1commit
pg_advisory_xact_lock

               
step s2insert: 
  INSERT INTO ctoast (key, val) VALUES (1, ctoast_large_val()) ON CONFLICT DO NOTHING;
 <waiting ...>
step s3insert: 
  INSERT INTO ctoast (key, val) VALUES (1, ctoast_large_val()) ON CONFLICT DO NOTHING;
 <waiting ...>
step s1commit: COMMIT;
step s2insert: <... completed>
step s3insert: <... completed>