数据库16:58出现大量4031，导致数据库无法使用，取对应时段的AWR
发现shared_pool一直在收缩；
查看日志：
** 2018-07-26 16:58:09.868
ORA-00604: 递归 SQL 级别 1 出现错误
ORA-04031: 无法分配 32 字节的共享内存 ("shared pool","select count() from sys.job...","sql area","tmp")
查看对应的trc:
LIBRARY CACHE STATISTICS:
namespace gets hit ratio pins hit ratio reloads invalids
-------------- --------- --------- --------- --------- ---------- ----------
CRSR 889957320 0.245 2974322326 0.877 6674225 3570108
出现大量的cursor无法共享；
并伴随出现：
last wait for 'SGA: allocation forcing component growth' blocking sess=0x0000000000000000 seq=62360 wait_time=7064 seconds since wait started=0
=0, =0, =0
Dumping Session Wait History
for 'SGA: allocation forcing component growth' count=1 wait_time=7064
=0, =0, =0
现察subpool:
Memory Utilization of Subpool 2
Allocation Name Size
_________________________ __________
"free memory " -2020262480
由于系统已重启，只能检查现在的resize情况：
set linesize 1000;
SELECT start_time,
component,
oper_type,
oper_mode,
initial_size/1048576 "INITIAL MB",
final_size/1048576 "FINAL MB",
end_time
FROM v$sga_resize_ops
WHERE component IN ( 'DEFAULT buffer cache', 'shared pool' )
AND status = 'COMPLETE'
ORDER BY start_time,
component;
发现调整还是很频繁；
检查历史的sga分配情况：发现故障时段大量的内存分配了kgh:no access
select * from DBA_HIST_SGASTAT where name in ('buffer_cache','sql area','KGH: NO ACCESS') and snap_id>40630
解决办法：
1 打补丁
Patch 7189722: APPSST GSI 10G : VERY FREQUENT GROW/SHRINK SGA RESIZE OPERATION HAPPENING
2 禁用ASMM功能；
参见MOS：
How To Prevent The Growth Of The Component 'KGH: NO ACCESS' In The Shared Pool When ASMM Is Enabled (Doc ID 451960.1)
Common Cause for ORA-4031 in 10gR2, Excess "KGH: NO ACCESS" Memory Allocation [Video] (Doc ID 801787.1)
3 依旧启用ASMM，但设置buffer cache/shared pool的最小值.
4 调整_memory_broker_stat_interval的值，减少sga 的auto resize频率；