- Only push events to websockets when we have subscribers

lib/logstash/outputs/websocket.rb

@@ -8,21 +8,27 @@ class LogStash::Outputs::Websocket < LogStash::Outputs::Base
 
   def register
     @channel = EventMachine::Channel.new
+    @subscribers = 0
     host = (@url.host or "0.0.0.0")
     port = (@url.port or 3000)
     EventMachine::WebSocket.start(:host => host, :port => port) do |ws|
       ws.onopen do
+        @subscribers += 1
         sid = @channel.subscribe do |msg| 
           ws.send msg
         end
         ws.onclose do
           @channel.unsubscribe(sid)
+          @subscribers -= 1
         end # ws.onclose
       end # ws.onopen
     end
   end # def register
 
   def receive(event)
-    @channel.push event.to_json
+    # Only publish the event to websockets if there are subscribers
+    if @subscribers > 0
+      @channel.push event.to_json
+    end
   end # def event
 end # class LogStash::Outputs::Websocket