How to do per-line profiling?

[Roy Smith]

Alex Martelli <aleax at aleax.it> wrote:
> Yes, package hotshot (part of the standard Python library) is just 
> such a tool.  Unfortunately, it's somewhat under-documented!

Thanks for the pointer -- at least it got me looking in the right place.  
Unfortunately, when I try to follow the examples from

http://www.python.org/dev/doc/devel//////lib/hotshot-example.html

I get:

Traceback (most recent call last):
  File "./rulex-diff.py", line 604, in ?
    stats = hotshot.stats.load ('profile-stats')
  File "/usr/local/lib/python2.2/hotshot/stats.py", line 12, in load
    return StatsLoader(filename).load()
  File "/usr/local/lib/python2.2/hotshot/stats.py", line 51, in load
    assert not self._stack
AssertionError

Here's what I tried:

    import hotshot, hotshot.stats
    import pstats
    app = rulexDiffApp()

    prof = hotshot.Profile ('profile-stats', 1, 1)
    prof.run ('app.main()')
    prof.close()

    stats = hotshot.stats.load ('profile-stats')
    stats.strip_dirs()
    stats.sort_stats('time', 'calls')
    stats.print_stats(20)

This is Python-2.2.2 on a RedHat 6.2 box.