Implement callgraphs

[markstory]

Build a nice looking way for developers to look at the critical path for a profile run. This visualization should let you see the following things:

• The critical path of the application should be highlighted.
• The wall time and percentage of request time should be shown for each heavy functions.
• Should look like a call tree.
• You should be able to get a callgraph for any profile run.

[liuggio]

:+1:

[rajiff]

Is there a sample screenshot for this or some pointers on how this will look (as per your wish, though i know what this is)

[markstory]

@rajiff Not yet, but I'll draw up a mockup see what you guys think of it. Originally I was thinking of using one of d3's flow graph types to do it. This, this and this are some places I was going to try starting from. Basically a graph that shows the call stacks in a tree form and indicates % of time used as color and thickness of connecting line. More time == bigger bars / darker colors.

[bertrandmalet]

I think a nice evolution of the callgraph feature could be an aggregted graph of multiple calls, for exemple within a period. It could be usefull to find real critical path from production servers excluding some rare expensive calls (eg cache refresh), pretty much like a 95th percentil.

[markstory]

I've been working on fixing the existing issues with the callgraph by exploring force directed graphs which can contain loops/cycles. Aggregated callgraphs are a neat idea, something to consider in the future for sure.

[markstory]

Callgraphs are working as far as I know. The critical path of any run is highlighted by size of the balls and thickness of lines connecting balls. Any other issues can be worked on separately in the future.