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| 1 | --- | ||
| 2 | title: Profiling Python web applications with visual tools | ||
| 3 | url: profiling-python-web-applications-with-visual-tools.html | ||
| 4 | date: 2017-04-21T12:00:00+02:00 | ||
| 5 | type: post | ||
| 6 | draft: false | ||
| 7 | --- | ||
| 8 | |||
| 9 | I have been profiling my software with KCachegrind for a long time now and I was | ||
| 10 | missing this option when I am developing API's or other web services. I always | ||
| 11 | knew that this is possible but never really took the time and dive into it. | ||
| 12 | |||
| 13 | Before we begin there are some requirements. We will need to: | ||
| 14 | |||
| 15 | - implement [cProfile](https://docs.python.org/2/library/profile.html#module-cProfile) into our web app, | ||
| 16 | - convert output to [callgrind](http://valgrind.org/docs/manual/cl-manual.html) format with [pyprof2calltree](https://pypi.python.org/pypi/pyprof2calltree/), | ||
| 17 | - visualize data with [KCachegrind](http://kcachegrind.sourceforge.net/html/Home.html) or [Profiling Viewer](http://www.profilingviewer.com/). | ||
| 18 | |||
| 19 | |||
| 20 | If you are using MacOS you should check out [Profiling | ||
| 21 | Viewer](http://www.profilingviewer.com/) or | ||
| 22 | [MacCallGrind](http://www.maccallgrind.com/). | ||
| 23 | |||
| 24 |  | ||
| 25 | |||
| 26 | We will be dividing this post into two main categories: | ||
| 27 | |||
| 28 | - writing simple web-service, | ||
| 29 | - visualize profile of this web-service. | ||
| 30 | |||
| 31 | ## Simple web-service | ||
| 32 | |||
| 33 | Let's use virtualenv so we won't pollute our base system. If you don't have | ||
| 34 | virtualenv installed on your system you can install it with pip command. | ||
| 35 | |||
| 36 | ```bash | ||
| 37 | # let's install virtualenv globally | ||
| 38 | $ sudo pip install virtualenv | ||
| 39 | |||
| 40 | # let's also install pyprof2calltree globally | ||
| 41 | $ sudo pip install pyprof2calltree | ||
| 42 | |||
| 43 | # now we create project | ||
| 44 | $ mkdir demo-project | ||
| 45 | $ cd demo-project/ | ||
| 46 | |||
| 47 | # now let's create folder where we will store profiles | ||
| 48 | $ mkdir prof | ||
| 49 | |||
| 50 | # now we create empty virtualenv in venv/ folder | ||
| 51 | $ virtualenv --no-site-packages venv | ||
| 52 | |||
| 53 | # we now need to activate virtualenv | ||
| 54 | $ source venv/bin/activate | ||
| 55 | |||
| 56 | # you can check if virtualenv was correctly initialized by | ||
| 57 | # checking where your python interpreter is located | ||
| 58 | # if command bellow points to your created directory and not some | ||
| 59 | # system dir like /usr/bin/python then everything is fine | ||
| 60 | $ which python | ||
| 61 | |||
| 62 | # we can check now if all is good ➜ if ok couple of | ||
| 63 | # lines will be displayed | ||
| 64 | $ pip freeze | ||
| 65 | # appdirs==1.4.3 | ||
| 66 | # packaging==16.8 | ||
| 67 | # pyparsing==2.2.0 | ||
| 68 | # six==1.10.0 | ||
| 69 | |||
| 70 | # now we are ready to install bottlepy ➜ web micro-framework | ||
| 71 | $ pip install bottle | ||
| 72 | |||
| 73 | # you can deactivate virtualenv but you will then go | ||
| 74 | # under system domain ➜ for now don't deactivate | ||
| 75 | $ deactivate | ||
| 76 | ``` | ||
| 77 | |||
| 78 | We are now ready to write simple web service. Let's create file app.py and paste | ||
| 79 | code bellow in this newly created file. | ||
| 80 | |||
| 81 | ```python | ||
| 82 | # -*- coding: utf-8 -*- | ||
| 83 | |||
| 84 | import bottle | ||
| 85 | import random | ||
| 86 | import cProfile | ||
| 87 | |||
| 88 | app = bottle.Bottle() | ||
| 89 | |||
| 90 | # this function is a decorator and encapsulates function | ||
| 91 | # and performs profiling and then saves it to subfolder | ||
| 92 | # prof/function-name.prof | ||
| 93 | # in our example only awesome_random_number function will | ||
| 94 | # be profiled because it has do_cprofile defined | ||
| 95 | def do_cprofile(func): | ||
| 96 | def profiled_func(*args, **kwargs): | ||
| 97 | profile = cProfile.Profile() | ||
| 98 | try: | ||
| 99 | profile.enable() | ||
| 100 | result = func(*args, **kwargs) | ||
| 101 | profile.disable() | ||
| 102 | return result | ||
| 103 | finally: | ||
| 104 | profile.dump_stats("prof/" + str(func.__name__) + ".prof") | ||
| 105 | return profiled_func | ||
| 106 | |||
| 107 | |||
| 108 | # we use profiling over specific function with including | ||
| 109 | # @do_cprofile above function declaration | ||
| 110 | @app.route("/") | ||
| 111 | @do_cprofile | ||
| 112 | def awesome_random_number(): | ||
| 113 | awesome_random_number = random.randint(0, 100) | ||
| 114 | return "awesome random number is " + str(awesome_random_number) | ||
| 115 | |||
| 116 | @app.route("/test") | ||
| 117 | def test(): | ||
| 118 | return "dummy test" | ||
| 119 | |||
| 120 | if __name__ == '__main__': | ||
| 121 | bottle.run( | ||
| 122 | app = app, | ||
| 123 | host = "0.0.0.0", | ||
| 124 | port = 4000 | ||
| 125 | ) | ||
| 126 | |||
| 127 | # run with 'python app.py' | ||
| 128 | # open browser 'http://0.0.0.0:4000' | ||
| 129 | ``` | ||
| 130 | |||
| 131 | When browser hits awesome\_random\_number() function profile is created in prof/ | ||
| 132 | subfolder. | ||
| 133 | |||
| 134 | ## Visualize profile | ||
| 135 | |||
| 136 | Now let's create callgrind format from this cProfile output. | ||
| 137 | |||
| 138 | ```bash | ||
| 139 | $ cd prof/ | ||
| 140 | $ pyprof2calltree -i awesome_random_number.prof | ||
| 141 | # this creates 'awesome_random_number.prof.log' file in the same folder | ||
| 142 | ``` | ||
| 143 | |||
| 144 | This file can be opened with visualizing tools listed above. In this case we | ||
| 145 | will be using Profilling Viewer under MacOS. You can open image in new tab. As | ||
| 146 | you can see from this example there is hierarchy of execution order of your | ||
| 147 | code. | ||
| 148 | |||
| 149 |  | ||
| 150 | |||
| 151 | > Make sure you convert output of the cProfile output every time you want to | ||
| 152 | refresh and take a look at your possible optimizations because cProfile updates | ||
| 153 | .prof file every time browser hits the function. | ||
| 154 | |||
| 155 | This is just a simple example but when you are developing real-life applications | ||
| 156 | this can be very illuminating, especially to see which parts of your code are | ||
| 157 | bottlenecks and need to be optimized. | ||
| 158 | |||
| 159 | ## Update 2017-04-22 | ||
| 160 | |||
| 161 | Reddit user [mvt](https://www.reddit.com/user/mvt) also recommended this awesome | ||
| 162 | web based profile visualizer [SnakeViz](https://jiffyclub.github.io/snakeviz/) | ||
| 163 | that directly takes output from | ||
| 164 | [cProfile](https://docs.python.org/2/library/profile.html#module-cProfile) | ||
| 165 | module. | ||
| 166 | |||
| 167 | <div class="reddit-embed" data-embed-media="www.redditmedia.com" data-embed-parent="false" data-embed-live="false" data-embed-uuid="583880c1-002e-41ed-a373-020a0ef2cff9" data-embed-created="2017-04-22T19:46:54.810Z"><a href="https://www.reddit.com/r/Python/comments/66v373/profiling_python_web_applications_with_visual/dgljhsb/">Comment</a> from discussion <a href="https://www.reddit.com/r/Python/comments/66v373/profiling_python_web_applications_with_visual/">Profiling Python web applications with visual tools</a>.</div><script async src="https://www.redditstatic.com/comment-embed.js"></script> | ||
| 168 | |||
| 169 | ```bash | ||
| 170 | # let's install it globally as well | ||
| 171 | $ sudo pip install snakeviz | ||
| 172 | |||
| 173 | # now let's visualize | ||
| 174 | $ cd prof/ | ||
| 175 | $ snakeviz awesome_random_number.prof | ||
| 176 | # this automatically opens browser window and | ||
| 177 | # shows visualized profile | ||
| 178 | ``` | ||
| 179 | |||
| 180 |  | ||
| 181 | |||
| 182 | Reddit user [ccharles](https://www.reddit.com/user/ccharles) suggested a better | ||
| 183 | way for installing pip software by targeting user level instead of using sudo. | ||
| 184 | |||
| 185 | <div class="reddit-embed" data-embed-media="www.redditmedia.com" data-embed-parent="false" data-embed-live="false" data-embed-uuid="f4f0459e-684d-441e-bebe-eb49b2f0a31d" data-embed-created="2017-04-22T19:46:10.874Z"><a href="https://www.reddit.com/r/Python/comments/66v373/profiling_python_web_applications_with_visual/dglpzkx/">Comment</a> from discussion <a href="https://www.reddit.com/r/Python/comments/66v373/profiling_python_web_applications_with_visual/">Profiling Python web applications with visual tools</a>.</div><script async src="https://www.redditstatic.com/comment-embed.js"></script> | ||
| 186 | |||
| 187 | ```bash | ||
| 188 | # now we need to add this path to our $PATH variable | ||
| 189 | # we do this my adding this line at the end of your | ||
| 190 | # ~/.bashrc file | ||
| 191 | PATH=$PATH:$HOME/.local/bin/ | ||
| 192 | |||
| 193 | # in order to use this new configuration you can close | ||
| 194 | # and reopen terminal or reload .bashrc file | ||
| 195 | $ source ~/.bashrc | ||
| 196 | |||
| 197 | # now let's test if new directory is present in $PATH | ||
| 198 | $ echo $PATH | ||
| 199 | |||
| 200 | # now we can install on user level by adding --user | ||
| 201 | # without use of sudo | ||
| 202 | $ pip install snakeviz --user | ||
| 203 | ``` | ||
| 204 | |||
| 205 | Or as suggested by [mvt](https://www.reddit.com/user/mvt) you can | ||
| 206 | use [pipsi](https://github.com/mitsuhiko/pipsi). | ||
