Troubleshooting: Oracle 19c wait event ‘latch: MGA shared context root latch’

最近一套客户环境从12C 升级19c(19.9)后在我们的监控上Wait class “Concurrency”等待告警进入TOP, 但是从V$SESSION和ASH view中的活动(active)的会话并未显示这么严重等待, AWR的top event中同样也不存在, 但是算在了Wait Classes by Total Wait Time和Background Wait Events里面,具体的wait event为“latch: MGA shared context root latch” , 1小时的AWR些latch wait 时间高达55,141秒,

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