# IPC (The Elephant Yell) ![[assets/wl_ipc.png|256]] **Inter-Process Communication (IPC)** represents the coordination between different parts of the Elephant Cafe. When the elephant is waiting on IPC, he isn't waiting on the disk or the network; he is waiting for another elephant to finish their part of the task. In Postgres, this is often the "Yelling" that happens during parallel query execution or when background workers (like the WalWriter or Checkpointer) need to stay in sync with the main backends. --- ![[Workloads/IPC/Parallel/_Parallel]] --- ![[Workloads/IPC/Hash/_Hash]] --- ![[Workloads/IPC/LogicalRep/_LogicalRep]] --- ![[Workloads/IPC/Recovery/_Recovery]] --- ![[Workloads/IPC/Coordination/_Coordination]]