brendankenny / call-trace

call-trace.js

Instruments a JavaScript file to record its call graph and (optionally) time spent in each function. When the file is run in the browser, a trace can be converted to the Chrome CPU profile format for viewing in DevTools.

Super buggy and doesn't work for most fairly normal code. Don't actually use this :)

Usage:

./call-trace.js input.js --time > output.js

When the output is loaded and then run, a global variable _$wɔk is created containing a trace through the code you just ran.

A CPU profile can be generated from the trace:

copy(JSON.stringify(_$wɔk.getReport()))

Then save your clipboard contents and load in Chrome DevTools.

Exploring the data

The global variable _$wɔk also has the following properties:

• file: the full path of the original source file.
• fns: a list of all functions found in the file.
• t: a record of the call graph. Positive values represent entering a function (with the value indicating a function in f) and negative values represent exiting a function (with the absolute value indexing f).
• d: a record of timestamps for every entry in t. Only created if the --time option was specified.

call-trace's Issues

<3

this

automating

need to add support for running on node and not having to copy(JSON.stringify(...)) like an idiot

You could use https://github.com/cyrus-and/chrome-remote-interface to evaluate that command. So probably something like...

# instrument a file
call-trace --instrument file.js > file.instrumented.js

# user runs it in a browser that's got debug port 9222 open (first tab ;)

# pull the results
call-trace --pull > output.cpuprofile