Крайне ожидаемое улучшение — Improved System Monitor (SMON) Process Scalability:
…SMON is responsible for cleaning up temporary segments that are no longer in use. SMON checks regularly to see whether it is needed, and other processes can call SMON. Temporary space management can affect SMON’s scalability for other critical actions. This new enhancement instead uses the Space Management Coordinator (SMCO) process so that the responsibility of managing temporary space is offloaded from SMON, thereby improving its scalability.
This feature improves the overall scalability of the SMON process, particularly in a multitenant Oracle RAC cluster.
Типичная связанная проблема:
19.10@ SQL> @ash_sql_wait3_dev "event = 'enq: SS - contention'" 0 "gv$active_session_history ash where sample_time between to_date('25.08.2022 11:00','dd.mm.yyyy hh24:mi') and to_date('25.08.2022 11:01','dd.mm.yyyy hh24:mi')" "SQL WAIT"
LVL INST_ID BLOCKING_TREE XID EVENT WAIT_CLASS Param[RAW] WAITS_COUNT EVENTS EXECS_COUNT AVG_WA SESS_COUNT BLOCKING_SID SQL_OPNAME MIN_STIME MAX_STIME SQL_ID TOP_LEVEL_SQL_ID SQL_PLAN_HASH
--- ------- ------------- --- --------------------- --------------- -------------- ----------- ---------- ----------- ------ ---------- ------------ --------------- -------------------------- -------------------------- ------------- ---------------- -------------
1 2 (USER) enq: SS - contention Configuration 4055 4055 0 0 94 VALID i#2 25-АВГ-22 11.00.00.536 AM 25-АВГ-22 11.00.59.745 AM 0
1 2 (USER) enq: SS - contention Configuration 2956 2956 0 31 62 VALID i#2 SELECT 25-АВГ-22 11.00.00.536 AM 25-АВГ-22 11.00.59.745 AM b79sx6p1rkxgy b79sx6p1rkxgy 707559059
1 2 (USER) X enq: SS - contention Configuration 2136 2136 0 61 65 VALID i#2 25-АВГ-22 11.00.00.536 AM 25-АВГ-22 11.00.59.745 AM 0
1 2 (USER) enq: SS - contention Configuration 1836 1836 41 34 41 VALID i#2 SELECT 25-АВГ-22 11.00.00.536 AM 25-АВГ-22 11.00.59.745 AM 0c39p8nazk5ks 0c39p8nazk5ks 198979182
1 2 (USER) enq: SS - contention Configuration 670 670 17 0 17 VALID i#2 INSERT 25-АВГ-22 11.00.00.536 AM 25-АВГ-22 11.00.59.745 AM a3xatmsxnm2cs a3xatmsxnm2cs 0
1 2 (USER) X enq: SS - contention Configuration 600 600 10 0 10 VALID i#2 SELECT 25-АВГ-22 11.00.00.536 AM 25-АВГ-22 11.00.59.745 AM 1pmcxrujj1c27 1pmcxrujj1c27 3326359747
1 2 (USER) enq: SS - contention Configuration 578 578 0 0 13 VALID i#2 25-АВГ-22 11.00.00.536 AM 25-АВГ-22 11.00.59.745 AM 0
1 2 (P...) enq: SS - contention Configuration 480 480 1 0 8 VALID i#2 SELECT 25-АВГ-22 11.00.00.536 AM 25-АВГ-22 11.00.59.745 AM 0zjsjfv10n7n9 0zjsjfv10n7n9 1136233048
1 2 (J...) enq: SS - contention Configuration 480 480 8 0 8 VALID i#2 PL/SQL EXECUTE 25-АВГ-22 11.00.00.536 AM 25-АВГ-22 11.00.59.745 AM 0qbzfjt00pbsx 0qbzfjt00pbsx 0
1 2 (P...) enq: SS - contention Configuration 420 420 1 0 7 VALID i#2 SELECT 25-АВГ-22 11.00.00.536 AM 25-АВГ-22 11.00.59.745 AM c0gv7nft03yt9 c0gv7nft03yt9 2134133020
...
2 2 (P...) X DFS lock handle Other 1128857605 14 17423 60 1 0 1 NO HOLDER i# SELECT 25-АВГ-22 11.00.00.536 AM 25-АВГ-22 11.00.59.745 AM dh412wkg65vzb dh412wkg65vzb 662588620
52 rows selected
— какой-то пользовательский процесс (в данном случае PX-slave, обозначаемый как (P…)) на ожидании DFS lock handle типа Cross-Instance Call Invocation с p2 = 14 (*) выстраивает очередь желающих получить немного места во временных (TEMP) сегментах: (more…)
Oracle mechanics 