Better document @profile usage

[dellis23]

It's unclear to me as to whether this is required, but after running without using this decorator anywhere, I got no results, so I'm assuming it is. I tried importing line_profiler in ipython and seeing if the decorator was there, but I didn't see it. I'm digging through the code now to see if I can figure it out.

[rkern]

Yes, it's always required. Does this new wording help?

aa1f425

[dellis23]

Well, my bigger issue right now is that I'm not sure how to actually import it. import profile doesn't work. I tried instantiating LineProfiler and using it as a decorator, but it gave no results. I tried importing __builtin__ and running kernprof with -b but I still just get this as the output when viewing with line_profiler:

Timer unit: 1e-06 s

[dellis23]

But yeah that new wording definitely makes it clear I need something, just not sure what yet.

[rkern]

You don't instantiate it. Running kernprof -b myscript.py injects it into the builtins.

[rkern]

Sorry, -b is for standard profiling. -l injects the LineProfiler into the builtins (search for "builtins" in the README).

[rkern]

The easiest way to
get started is to use the `kernprof` script. ::

    $ kernprof -l script_to_profile.py

`kernprof` will create an instance of LineProfiler and insert it into the
`__builtins__` namespace with the name `profile`. It has been written to be
used as a decorator, so in your script, you decorate the functions you want
to profile with @profile. ::

    @profile
    def slow_function(a, b, c):
        ...

[dellis23]

Hmm. Perhaps it just isn't working for me then, and isn't a documentation issue:

blah@dan:~/myapp$ kernprof -l app.py -b
Traceback (most recent call last):
  File "app.py", line 107, in <module>
    @profile
NameError: name 'profile' is not defined
Wrote profile results to app.py.lprof

[rkern]

Is the -b for your app.py?

[dellis23]

No, it doesn't take any arguments. Without the -b gives the same issue. If no one else is experiencing this maybe it's some edge case with my setup (though I can't imagine what that might be). I can close the issue unless you want to keep exploring it; I know this isn't tech support and I don't want to waste your time.

[rkern]

Can you upload (gist) an app.py that is causing problems?

[rkern]

Do omit the -b. It is mutually exclusive with -l.

[dellis23]

It would take me too long to redact all the sensitive stuff, but here's a smaller version that recreates the same issue: https://gist.github.com/dellis23/d5251031787ff370f15f

And the output:

blah@dan:~/testflask$ kernprof -l app.py 
 * Running on http://127.0.0.1:3000/
 * Restarting with reloader
162.222.72.1 - - [16/Jan/2015 10:34:28] "GET / HTTP/1.1" 200 -
^CWrote profile results to app.py.lprof
blah@dan:~/testflask$ python -m line_profiler app.py.lprof
Timer unit: 1e-06 s

[rkern]

There's no @profile in there. Are you trying to combine it with the @app.route('/') decorator? For various reasons, that may or may not work.

[rkern]

You have some options, like refactoring the body of the function to a function all by itself, @profile that one, and have the @app.routed function call that one.

Also try a non-Flask script to see if line_profiler is just totally broken on your system or if it's just not working with Flask.

[dellis23]

Doh, yeah, I put the @profile in and had the same results. But I think you're right, it's either a Flask issue or a problem with the multiple decorators. Running a small, non-flask dummy script confirmed that it's not just my system.

Thanks for the help -- hopefully it at least guides someone else in the right direction if they are trying it with Flask.

[rkern]

Thanks. I've added an issue to document the issues with multiple decorators. #19

[stickytruth]

This seems to be an issue with flask's reloader, rather than an issue of multiple decorators. Also, Flask's documentation mentions "When applying further decorators, always remember that the route() decorator is the outermost"

An example of kernprof working with flask can be seen in this gist: https://gist.github.com/stickytruth/39c3fa2c88f141a0a26b

[rkern]

Ah, good detective work! Thanks!

[Downchuck]

I ran into this issue in virtualenv -- are there issues there?

NameError: name 'profile' is not defined