有关errorstack
Errorstack is an internal event and should only be set on the advice of Oracle Support.
oradebug dump errorstack 3
Dumps the process stack and process state for the current process.
Errorstack captures process state dumps and context areas (level 3)
Errorstack is an internal event and should only be set on the advice of Oracle Support.
oradebug dump errorstack 3
Dumps the process stack and process state for the current process.
Errorstack captures process state dumps and context areas (level 3)
参考自：
How to Collect Errorstacks for use in Diagnosing Performance Issues. (文档 ID 1364257.1)
How to Diagnose High cpu Usage Problems to the Module Level (文档 ID 352648.1)