multithreadingsequence-diagramuml
How can you clearly illustrate multiple threads of execution in a sequence diagram or similar diagram?
I haven't been able to find any clear examples. All diagrams I see are used to illustrate a single thread.
Update: The accepted answer was the best example I saw but it does leave a fair bit to be desired. I ended up illustrating the threads in separate sequence diagrams. I'm not sure if the sequence diagram necessarily works for multiple threads.
Is what I used. It is easily installed from the repository:
Name: ObjectAid UML Explorer
Location: http://www.objectaid.com/update/current
And produces quite nice UML diagrams:
The ObjectAid UML Explorer is different from other UML tools. It uses the UML notation to show a graphical representation of existing code that is as accurate and up-to-date as your text editor, while being very easy to use. Several unique features make this possible:
- Your source code and libraries are the model that is displayed, they are not reverse engineered into a different format.
- If you update your code in Eclipse, your diagram is updated as well; there is no need to reverse engineer source code.
- Refactoring updates your diagram as well as your source code. When you rename a field or move a class, your diagram simply reflects the changes without going out of sync.
- All diagrams in your Eclipse workspace are updated with refactoring changes as appropriate. If necessary, they are checked out of your version control system.
- Diagrams are fully integrated into the Eclipse IDE. You can drag Java classes from any other view onto the diagram, and diagram-related information is shown in other views wherever applicable.
The simplest way is an anonymous method passed into Label.Invoke:
// Running on the worker thread
string newText = "abc";
form.Label.Invoke((MethodInvoker)delegate {
// Running on the UI thread
form.Label.Text = newText;
});
// Back on the worker thread
Notice that Invoke blocks execution until it completes--this is synchronous code. The question doesn't ask about asynchronous code, but there is lots of content on Stack Overflow about writing asynchronous code when you want to learn about it.
Best Answer
Here is one diagram that may be useful, and on the left-hand side you can see the explanation: http://sdedit.sourceforge.net/multithreading/example/index.html