Parsed test spec with 4 sessions

starting permutation: d1a1 d2a2 e1l e2l d1a2 d2a1 d1c e1c d2c e2c
step d1a1: LOCK TABLE a1 IN ACCESS SHARE MODE;
step d2a2: LOCK TABLE a2 IN ACCESS SHARE MODE;
step e1l: LOCK TABLE a1 IN ACCESS EXCLUSIVE MODE; <waiting ...>
step e2l: LOCK TABLE a2 IN ACCESS EXCLUSIVE MODE; <waiting ...>
step d1a2: LOCK TABLE a2 IN ACCESS SHARE MODE; <waiting ...>
step d2a1: LOCK TABLE a1 IN ACCESS SHARE MODE; <waiting ...>
step d1a2: <... completed>
step d1c: COMMIT;
step e1l: <... completed>
step e1c: COMMIT;
step d2a1: <... completed>
step d2c: COMMIT;
step e2l: <... completed>
step e2c: COMMIT;