Diagram of a Logical Thread Execution

Question

Hi guys

After some days studying about call context and logical thread execution, I've designed an illustration about this topic. I'll be happy if you let me know your opinion about that and I hope I've understood the subject correctly.

Thank you

T1, T2, Ti are Threads. The small black circle is where a thread finishes its execution. The diagram is a mixture of sequence, collaboration and activitiy diagram.

Answer 1

Please provide bit more context , also is Machine>> Processor ?