Oracle 11.2.0.3 alert log 發現LG01 waits for event 'log file parallel write' for xx secs訊息 and kjgcr_statcheckcpu runq based load is high

bug 1.
Alert log 出現 : LG01 (ospid: 24656) waits for event 'log file parallel write' for 89 secs
                 LGWR (ospid: 24648) waits for event 'LGWR any worker group' for 77 secs

應該是這篇所提之隱藏參數, 預設在11.2.0.3 會自動invoke 多個writer process, 但開啟後會造成大量的log file 等待事件
Multiple Log Writers in 12c Causing Enabling and Disabling of Adaptive Scalable Log Writer Workers Which Cause High 'log file sync' Wait Event (Doc ID 2174075.1)

SYMPTOMS
The database slows down, or appears to hang occasionally, with many sessions waiting on wait event 'log file sync'
AWR report indicates heavy wait time on 'log file sync'

Sol:
alter system set "_use_adaptive_log_file_sync"=false sid='*';


bug 2.
Alert log : 出現的是kjgcr_statcheckcpu：runq based load is high

Bug 20076781 - LMHB reports "kjgcr_StatCheckCPU: runq based load is high" (Doc ID 20076781.8)


bug1要調參數 而bug2要上patch

同時在12c DB的auto datafile resize 也在當下發生, 造成IO system又更慢了


ref:
https://jaychu649.blogspot.tw/2012/08/oracle-8i-upgrade-to-9i-9i-upgrade-to.html
Multiple Log Writers in 12c Causing Enabling and Disabling of Adaptive Scalable Log Writer Workers Which Cause High 'log file sync' Wait Event (Doc ID 2174075.1)