heavy latch contention “simulator lru latch” bug
oracle 六月 25th, 2008今天客户数据库出现故障，登录查看，除了sql效率低下外，发现了一个oracle bug from metalink Note:5918642.8
Bug 5918642 - Heavy latch contention with DB_CACHE_ADVICE on
其中的latch就是指 simulator lru latch
解决办法就是升级10.2.0.4或者设置db_cache_advice=off
SQL> l
1 select sample_time,name ,count(*)
2 from ash_tmp,v$latch_children
3 where addr=’0000000′||trim(to_char(p1,’XXXXXXXXX’))
4 and event=’latch free’
5 group by sample_time,name
6* order by 3 desc
SQL> /
SAMPLE_TIME NAME COUNT(*)
————————————————————————— —————————— ———-
25-JUN-08 04.37.04.960 PM simulator lru latch 132
25-JUN-08 04.37.26.880 PM simulator lru latch 90
25-JUN-08 04.37.13.950 PM simulator lru latch 75
25-JUN-08 04.37.55.470 PM simulator lru latch 68
25-JUN-08 04.37.05.970 PM simulator lru latch 58
25-JUN-08 04.36.13.940 PM simulator lru latch 50
25-JUN-08 04.37.14.990 PM simulator lru latch 42
25-JUN-08 04.37.27.910 PM simulator lru latch 39
25-JUN-08 04.37.06.981 PM simulator lru latch 31
25-JUN-08 04.37.16.000 PM simulator lru latch 29
25-JUN-08 04.37.56.480 PM simulator lru latch 16
25-JUN-08 04.37.08.001 PM simulator lru latch 13
