What is ‘rdbms ipc message’ wait event?

Introduction There was a question about the wait event 'rdbms ipc message' in Oracle-l list. Short answer is that 'rdbms ipc message' event means that a process is waiting for an IPC message to arrive. Usually, this wait event can be ignored, but there are few rare scenarios this wait event can't be completely ignored. What is 'rdbms ipc message' wait means? It is typical of Oracle Database background processes to wait for more ...