Parsed test spec with 3 sessions

starting permutation: s1_begin s2_begin s3_begin s1_update s2_key_share s3_key_share s1_update s1_commit s2_commit s2_vacuum s1_selectone s3_commit s2_vacuum s1_selectall
step s1_begin: BEGIN;
step s2_begin: BEGIN;
step s3_begin: BEGIN;
step s1_update: UPDATE tab_freeze SET x = x + 1 WHERE id = 3;
step s2_key_share: SELECT id FROM tab_freeze WHERE id = 3 FOR KEY SHARE;
id
--
 3
(1 row)

step s3_key_share: SELECT id FROM tab_freeze WHERE id = 3 FOR KEY SHARE;
id
--
 3
(1 row)

step s1_update: UPDATE tab_freeze SET x = x + 1 WHERE id = 3;
step s1_commit: COMMIT;
step s2_commit: COMMIT;
step s2_vacuum: VACUUM FREEZE tab_freeze;
step s1_selectone: 
    BEGIN;
    SET LOCAL enable_seqscan = false;
    SET LOCAL enable_bitmapscan = false;
    SELECT * FROM tab_freeze WHERE id = 3;
    COMMIT;

id|name|x
--+----+-
 3| 333|2
(1 row)

step s3_commit: COMMIT;
step s2_vacuum: VACUUM FREEZE tab_freeze;
step s1_selectall: SELECT * FROM tab_freeze ORDER BY name, id;
id|name|x
--+----+-
 1| 111|0
 3| 333|2
(2 rows)