Why Running?

This view works with the Timeline pane to provide developers with a single-click answer to the question: “Why is this thread running?” In this context, “this thread” refers to the owner of the currently selected event.

Why Running? view
First, you must click an event tick mark in the Timeline pane. The editor highlights the owner's name and draws an arrow pointing downwards, just above the event. Then, you can click Find Running/Reason in the Why Running? view to populate it with event information showing why the current thread could run. Two events are listed:
  • The Running event for the current thread
  • The event that made the previously running thread change state, allowing the current thread to run

To learn why the previously running thread could run earlier, click Previous Running/Reason to see the two events related to that thread's transition to the Running state. You can repeat this action to get a clear view of the sequence of activities that led to the original execution position. Or, you can click Trace Entire Running/Reason Chain (either just after you clicked an event tick mark or any time when you see the partial execution sequence) to display the entire backtrace of Running events.

If you click a tick mark for a procnto idle thread or the Previous Running/Reason button when the entire backtrace is already displayed, you'll get a message saying the end of the chain was detected, and no new events will be listed.

Note: Don't confuse the Running backtraces shown here with the call stacks shown by the Memory Backtrace view when you're debugging memory problems. The Running backtraces reveal the cause/effect relationship between threads that led to current thread's execution whereas the memory backtraces show the function call sequence for only the current thread's execution position.