title: UML for multithreading dataflow
body: <p>I want to paint a diagram where you can see the dataflow of a java program, and if there are one or multiple threads handling the data.</p>
  
  <p>Sequence charts don't show multithreading and get very confusion when you have more than 5 different entities.</p>
  
  <p>Class diagrams are good for showing the relations but the dataflow is missing.</p>
  
  <p>I would like to paint boxes (like class/package diagram) and connect them. Maybe having a box doubled and <code>...</code> in between to show that there can be more than one thread.</p>
  
  <p>What diagram does UML have for this kind of dataflow diagram?</p>
  
  <p>What editor is good for that diagram? If possible freeware or open source.</p>