How to illustrate multiple threads in sequence diagram?

multithreading uml sequence-diagram
Marcus Leon picture Marcus Leon · Oct 29, 2009 · Viewed 81.6k times · Source

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.

Answer

James Black picture James Black · Oct 29, 2009

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

Multithreading Sequence Diagram

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