Rob Sayre's Mozilla Blog

This little script takes Spin Control output from a running process and tries to demangle the symbols to get sample stacks. It was just a quick hack. Someone make it better!

I used the script to file bug 515447. You can use it by turning on Spin Control and running it on the text file output. I don’t know why Spin Control can’t find the symbols itself. There are also some other options for running atos that probably don’t need a running process. You’ll need a build that has symbols, like the Shark-enabled nightlies do.

from __future__ import with_statement
from subprocess import Popen, PIPE

firefox_pid = 85034
spin_file_path = "/Users/sayrer/Desktop/spinout.txt"

class memoize:
  def __init__(self, function):
    self.function = function
    self.memoized = {}

  def __call__(self, *args):
    try:
      return self.memoized[args]
    except KeyError:
      self.memoized[args] = self.function(*args)
      return self.memoized[args]

@memoize
def findSymbol(word):
    # run atos
    cmd = ["atos", "-p", str(firefox_pid), word]
    proc = Popen(cmd, stdout=PIPE)
    stdout, stderr = proc.communicate()
    return stdout[0:-1]

def demangle(words):
    output = ""
    for word in words:
        if word.startswith("0x"):
            word = findSymbol(word)
        output += " " + word
    return output

with open(spin_file_path) as a_file:
    for line in a_file.readlines():
        indent = len(line) - len(line.lstrip())
        words = line.split()
        print line[0:indent], demangle(words)

Feel free to improve.