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| 55 | <H1><A NAME="SECTION0012300000000000000000"></A><A NAME="profile-instant"></A> |
| 56 | <BR> |
| 57 | 10.3 Instant Users Manual |
| 58 | </H1> |
| 59 | |
| 60 | <P> |
| 61 | This section is provided for users that ``don't want to read the |
| 62 | manual.'' It provides a very brief overview, and allows a user to |
| 63 | rapidly perform profiling on an existing application. |
| 64 | |
| 65 | <P> |
| 66 | To profile an application with a main entry point of <tt class="function">foo()</tt>, |
| 67 | you would add the following to your module: |
| 68 | |
| 69 | <P> |
| 70 | <div class="verbatim"><pre> |
| 71 | import profile |
| 72 | profile.run('foo()') |
| 73 | </pre></div> |
| 74 | |
| 75 | <P> |
| 76 | The above action would cause <tt class="function">foo()</tt> to be run, and a series of |
| 77 | informative lines (the profile) to be printed. The above approach is |
| 78 | most useful when working with the interpreter. If you would like to |
| 79 | save the results of a profile into a file for later examination, you |
| 80 | can supply a file name as the second argument to the <tt class="function">run()</tt> |
| 81 | function: |
| 82 | |
| 83 | <P> |
| 84 | <div class="verbatim"><pre> |
| 85 | import profile |
| 86 | profile.run('foo()', 'fooprof') |
| 87 | </pre></div> |
| 88 | |
| 89 | <P> |
| 90 | The file <span class="file">profile.py</span> can also be invoked as |
| 91 | a script to profile another script. For example: |
| 92 | |
| 93 | <P> |
| 94 | <div class="verbatim"><pre> |
| 95 | python -m profile myscript.py |
| 96 | </pre></div> |
| 97 | |
| 98 | <P> |
| 99 | <span class="file">profile.py</span> accepts two optional arguments on the command line: |
| 100 | |
| 101 | <P> |
| 102 | <div class="verbatim"><pre> |
| 103 | profile.py [-o output_file] [-s sort_order] |
| 104 | </pre></div> |
| 105 | |
| 106 | <P> |
| 107 | <b class="programopt">-s</b> only applies to standard output (<b class="programopt">-o</b> is |
| 108 | not supplied). Look in the <tt class="class">Stats</tt> documentation for valid sort |
| 109 | values. |
| 110 | |
| 111 | <P> |
| 112 | When you wish to review the profile, you should use the methods in the |
| 113 | <tt class="module">pstats</tt> module. Typically you would load the statistics data as |
| 114 | follows: |
| 115 | |
| 116 | <P> |
| 117 | <div class="verbatim"><pre> |
| 118 | import pstats |
| 119 | p = pstats.Stats('fooprof') |
| 120 | </pre></div> |
| 121 | |
| 122 | <P> |
| 123 | The class <tt class="class">Stats</tt> (the above code just created an instance of |
| 124 | this class) has a variety of methods for manipulating and printing the |
| 125 | data that was just read into <code>p</code>. When you ran |
| 126 | <tt class="function">profile.run()</tt> above, what was printed was the result of three |
| 127 | method calls: |
| 128 | |
| 129 | <P> |
| 130 | <div class="verbatim"><pre> |
| 131 | p.strip_dirs().sort_stats(-1).print_stats() |
| 132 | </pre></div> |
| 133 | |
| 134 | <P> |
| 135 | The first method removed the extraneous path from all the module |
| 136 | names. The second method sorted all the entries according to the |
| 137 | standard module/line/name string that is printed (this is to comply |
| 138 | with the semantics of the old profiler). The third method printed out |
| 139 | all the statistics. You might try the following sort calls: |
| 140 | |
| 141 | <P> |
| 142 | <div class="verbatim"><pre> |
| 143 | p.sort_stats('name') |
| 144 | p.print_stats() |
| 145 | </pre></div> |
| 146 | |
| 147 | <P> |
| 148 | The first call will actually sort the list by function name, and the |
| 149 | second call will print out the statistics. The following are some |
| 150 | interesting calls to experiment with: |
| 151 | |
| 152 | <P> |
| 153 | <div class="verbatim"><pre> |
| 154 | p.sort_stats('cumulative').print_stats(10) |
| 155 | </pre></div> |
| 156 | |
| 157 | <P> |
| 158 | This sorts the profile by cumulative time in a function, and then only |
| 159 | prints the ten most significant lines. If you want to understand what |
| 160 | algorithms are taking time, the above line is what you would use. |
| 161 | |
| 162 | <P> |
| 163 | If you were looking to see what functions were looping a lot, and |
| 164 | taking a lot of time, you would do: |
| 165 | |
| 166 | <P> |
| 167 | <div class="verbatim"><pre> |
| 168 | p.sort_stats('time').print_stats(10) |
| 169 | </pre></div> |
| 170 | |
| 171 | <P> |
| 172 | to sort according to time spent within each function, and then print |
| 173 | the statistics for the top ten functions. |
| 174 | |
| 175 | <P> |
| 176 | You might also try: |
| 177 | |
| 178 | <P> |
| 179 | <div class="verbatim"><pre> |
| 180 | p.sort_stats('file').print_stats('__init__') |
| 181 | </pre></div> |
| 182 | |
| 183 | <P> |
| 184 | This will sort all the statistics by file name, and then print out |
| 185 | statistics for only the class init methods (since they are spelled |
| 186 | with <code>__init__</code> in them). As one final example, you could try: |
| 187 | |
| 188 | <P> |
| 189 | <div class="verbatim"><pre> |
| 190 | p.sort_stats('time', 'cum').print_stats(.5, 'init') |
| 191 | </pre></div> |
| 192 | |
| 193 | <P> |
| 194 | This line sorts statistics with a primary key of time, and a secondary |
| 195 | key of cumulative time, and then prints out some of the statistics. |
| 196 | To be specific, the list is first culled down to 50% (re: "<tt class="samp">.5</tt>") |
| 197 | of its original size, then only lines containing <code>init</code> are |
| 198 | maintained, and that sub-sub-list is printed. |
| 199 | |
| 200 | <P> |
| 201 | If you wondered what functions called the above functions, you could |
| 202 | now (<code>p</code> is still sorted according to the last criteria) do: |
| 203 | |
| 204 | <P> |
| 205 | <div class="verbatim"><pre> |
| 206 | p.print_callers(.5, 'init') |
| 207 | </pre></div> |
| 208 | |
| 209 | <P> |
| 210 | and you would get a list of callers for each of the listed functions. |
| 211 | |
| 212 | <P> |
| 213 | If you want more functionality, you're going to have to read the |
| 214 | manual, or guess what the following functions do: |
| 215 | |
| 216 | <P> |
| 217 | <div class="verbatim"><pre> |
| 218 | p.print_callees() |
| 219 | p.add('fooprof') |
| 220 | </pre></div> |
| 221 | |
| 222 | <P> |
| 223 | Invoked as a script, the <tt class="module">pstats</tt> module is a statistics |
| 224 | browser for reading and examining profile dumps. It has a simple |
| 225 | line-oriented interface (implemented using <tt class="module"><a href="module-cmd.html">cmd</a></tt>) and |
| 226 | interactive help. |
| 227 | |
| 228 | <P> |
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| 264 | <span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span> |
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