Monthly Archives: March 2008

Mozilla JavaScript DTrace Probes, visichron style

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 dtrace javascript snippet

This visualization is the result of an adapted visichron.py script (from my chronicle-recorder ‘chroniquery’ bindings) run against the output of a custom DTrace script (using the Mozilla JS providers) on OS X.  It’s a proof-of-possibility rather than anything immediately useful.

The differences from the last visichron post (using chronicle-recorder as a back-end) are:

  • Node hues are distinct based on the file the javascript was executed from.  (Saturation still varies with amount of time spent in the function.)
  • Graph layout is done using graphviz’s neato’s “ipsep” (experimental) mode.  This works fantastically well at reducing/eliminating overlap.  Having said that, a hierarchical layout may make more sense.
  • Ring colors are based on call depth (so redundantly encoded with the ring radius) rather than any knowledge about the control-flow.  Full control-flow information is not readily available and would be extremely expensive, but we could provide at least some degree of approximation using the calls made by the function as indicators.  Of course, the ring visualization at this point and for this purpose is probably better represented as non-nested (side-by-side rings of different radii; not containing each other) faux-continuous ring slices with transparency varying by amount of time spent in the function at that call-depth.  This would simplify the object model, allowing for non-insane use of the SVG backend and interactivity enhancements.

scaled indexed

status/future fyi. no pictures.

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I have accepted a position at Mozilla Messaging and will start at the end of March. Posting has been rare as of late and will be rare until then because my spare cycles are being given over to providing closure to my day-job projects, dealing with various hardware failures, and other small fires.

Hobby-wise, this will translate into a focus on visualizing e-mail from within Thunderbird. My nascent Python library, visophyte, will likely have a JavaScript sibling, but will not be abandoned.

Job-wise, I expect to focus on improving Thunderbird for both users and extension developers. Although my interest in creating a useful visualization extension will inform my efforts, it will not be my focus. Which is to say, do not worry that I will be engaging in flights of fancy and neglecting the core of Thunderbird. However, do be happy that good visualizations will depend on non-trivial data analysis and snappy, interactive behaviour and that this should translate into good things for Thunderbird, even if you don’t like shiny things.

It wasn’t an easy decision to leave my current employer (I have only great things to say about The PTR Group; check them out if you’re in the greater DC metro area), but Mozilla Messaging is an exceedingly rare opportunity that I could not pass up.