@startuml
participant Thread1 order 1
participant Thread2 order 2
collections EventQueue order 3
participant StreamOwner order 4
participant OutputStream order 5

Thread1 -> EventQueue: offer
Thread2 -> EventQueue: offer
group while (!done)
StreamOwner -> EventQueue: poll
StreamOwner -> OutputStream: write
activate OutputStream
StreamOwner <- OutputStream: ack
deactivate OutputStream
end
@enduml