12.2 wait event ‘PGA memory operation’
一客戶報整個資料庫sql執行緩慢,甚至執行不出來。
看了下會話,等待事件都是PGA memory operation,等待時間長達幾百秒。
PGA memory operation等待事件在12.2開始引入,從字面上看是會話記憶體分配。
具體看了下等待事件原理。是在等待系統分配記憶體過程。理論上,一程式分配記憶體最多是毫秒級別。莫非系統記憶體出現問題。
https://fritshoogland.wordpress.com/2017/03/01/oracle-12-2-wait-event-pga-memory-operation/
LINUX平臺,看下了memory info,果然,PageTables達到了12GB,那不慢才怪。
PageTables: 12935688 kB
問題是大頁設定了,但使用者資源引數設小了,導致用不到大頁。sga和pga都使用4k的頁,導致PageTables龐大。
調整後,重啟資料庫,一切正常。
看了下會話,等待事件都是PGA memory operation,等待時間長達幾百秒。
PGA memory operation等待事件在12.2開始引入,從字面上看是會話記憶體分配。
具體看了下等待事件原理。是在等待系統分配記憶體過程。理論上,一程式分配記憶體最多是毫秒級別。莫非系統記憶體出現問題。
https://fritshoogland.wordpress.com/2017/03/01/oracle-12-2-wait-event-pga-memory-operation/
LINUX平臺,看下了memory info,果然,PageTables達到了12GB,那不慢才怪。
PageTables: 12935688 kB
問題是大頁設定了,但使用者資源引數設小了,導致用不到大頁。sga和pga都使用4k的頁,導致PageTables龐大。
調整後,重啟資料庫,一切正常。
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