digraph SMPServer {
  graph [fontname=arial]
  node [fontname=arial fontsize=11 shape=box]
  edge [fontname=arial fontsize=10 arrowhead=open arrowtail=open]

  subgraph clusterPersistence {
    label="persistence (STM)"
    msgQueues [shape=cylinder label="Message\nqueues"]
    queueStore [shape=cylinder label="SMP queue\nrecords"]
  }

  subgraph clusterServer {
    label="server threads" 
    main [shape=hexagon color=orange label="main\nthread"]
    ss [label="server TCP socket" color=blue]
    subgraph clusterThreads {
      label="" 
      node [shape=hexagon color=orange]
      runClient [label="runClient\nthread"]
      server [label="server\nthread"]
    }
    subscribedQ [shape="larrow" label="subscribed\nTBQueue"]
    main -> {server runClient} [style=dashed label=race color=orange fontcolor=orange]
    ss -> runClient [color=blue]
    subscribedQ -> server
  }

  subgraph clusterConnection {
    label="1 group per client connection"
    cs [label="client connection TCP socket" color=blue]

    subgraph clusterThreads {
      node [shape=hexagon, color=orange]
      label=""
      receive [label="receive\nthread"]
      client [label="client\nthread"]
      send [label="send\nthread"]
    }

    runClient -> cs [style=dashed label="connect" color=blue fontcolor=blue]
    runClient -> {client receive send} [style=dashed label=race color=orange fontcolor=orange]
    server -> inq [label="END"]

    subscriber [shape=hexagon color=orange label="subscriber\nthread"]

    inq [shape=rarrow label="receive\nTBQueue"]
    outq [shape=larrow label="send\nTBQueue"]
    cs -> receive -> inq -> client [color=blue]
    msgQueues -> subscriber [label="Message" color=green fontcolor=green]
    subscriber -> outq [label="MSG" color=blue fontcolor=blue constraint=false]
    client -> queueStore [dir=both]
    client -> subscriber [style=dashed label="1 fork per\nSMP queue" color=orange]
    client -> msgQueues [dir="both" label="SEND,\nSUB,\nACK" color=green]
    client -> outq -> send -> cs [color=blue]
    client -> subscribedQ [label="(rId, Client)"]
  }
}