V$SESSION_BLOCKERS displays the blocker sessions for each blocked session. Each row represents a blocked and blocker session pair. If a session is blocked by multiple sessions there will be multiple rows for that blocked session. The maximum number of blocker sessions displayed for a single blocked session is 30. If a session is not blocked by other sessions, then there will be no row in this view for that session.
Blocked session's Oracle session identifier
Blocked session's Oracle session serial number
A number identifying the wait for the blocked session
Resource or event number for which the blocked session is waiting
Resource or event for which the blocked session is waiting
Blocker session's instance identifier
Blocker session's Oracle session identifier
Blocker session's Oracle session serial number
The ID of the container to which the data pertains. Possible values include:
0: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs.
1: This value is used for rows containing data that pertain to only the root
n: Where n is the applicable container ID for the rows containing data