I sometimes trouble-shoot and analyse the cause of long time spending job.
At the time, I find the stages which spends long time or fails, then I find the tasks which spends long time or fails, next I analyse the proportion of each phase in a task.
Another case, I find executors which spends long time for running a task and analyse the details of a task.
In such situation, I think it's helpful to visualize timeline view of stages / tasks / executors and visualize details of proportion of activity for each task.
Now I'm developing prototypes like captures I attached.
I'll integrate these viewer into WebUI.