Parsed test spec with 2 sessions

starting permutation: s1a s2a s1b s1c s2c
step s1a: LOCK TABLE a1 IN ACCESS EXCLUSIVE MODE;
step s2a: LOCK TABLE a1 IN EXCLUSIVE MODE; <waiting ...>
step s1b: LOCK TABLE a1 IN SHARE ROW EXCLUSIVE MODE NOWAIT;
step s1c: COMMIT;
step s2a: <... completed>
step s2c: COMMIT;