importtime-output-wrapper 1.0.2

A tool to parse the output of the importtime implementaion.

importtime output wrapper

Starting from the Python3.7 release, the -X importtime option is available. It can be used to measure the import time for any python module, including all nested imports.

The official documentaion for this function can be found here: https://docs.python.org/3.7/using/cmdline.html#id5

Installation

pip install importtime-output-wrapper

Implemented features

The implementaion prints out the output to the stderr in string format. To actually use this output for benchmarking, I wrote this simple wrapper, that parses the output and puts it into a usable json format.

Alternatively, the tool can format the output as a waterfall digram. However, this feature only serves to provide a quick overview.

The importtime-output-wrapper can also sort the imported modules (and their nested imports) by the time they needed.

It has a command-line interface that works as follows:

$ importtime-output-wrapper [-h] [--sort [{self,cumulative}]] module

As module any python module can be provided. The optional argument --sort will sort the output either by the time every module needed to import (--sort self) or by the cumulative time (--sort cumulative).

output as json

For example: calling $ python -X importtime -c "import os" would produce the following (reduced) output:

import time: self [us] | cumulative | imported package
import time:      1504 |       1504 | _frozen_importlib_external
import time:      1073 |       1073 |   time
import time:      1749 |       2821 | zipimport
[...]

...and insted if you call $ importtime-output-wrapper os, it will produce the following (reduced) output:

[
  {
    "name": "_frozen_importlib_external",
    "depth": 1,
    "t_self_us": 610,
    "t_cumulative_us": 610,
    "nested_imports": []
  },
  {
    "name": "zipimport",
    "depth": 1,
    "t_self_us": 230,
    "t_cumulative_us": 567,
    "nested_imports": [
      {
        "name": "time",
        "depth": 2,
        "t_self_us": 337,
        "t_cumulative_us": 337,
        "nested_imports": []
      }
    ]
  },
  [...]
]

output as waterfall diagram

As an additional feature, the program can also display the output as a waterfall digram in the terminal. For the above example, calling $ importtime-output-wrapper os --format waterfall results in the following (reduced) output:

module name                | import time (us)
-------------------------------------------------------------------------------
_frozen_importlib_external    ========(576)
zipimport                     ====(280)
.time                         ======(413)
encodings                     =====================(1410)
.codecs                       ==========(688)
.._codecs                     =(75)
.encodings.aliases            ===========(762)
encodings.utf_8               =====(328)
[...]
site                          ===========================================(2865)
.os                           ==========(684)
..stat                        =======(509)
..._stat                      (54)
.._collections_abc            =================(1155)
..posixpath                   =====(385)
...genericpath                ====(277)
._sitebuiltins                ====(289)
._bootlocale                  ===(249)
.._locale                     =(70)
[...]

The output is scaled to 79 characters. The number behind the bar indicates the import time in microseconds.

I personally used this tool to sort the output of the -X importtime implementaion to index modules that were slowing down the startup of a larger project. Maybe someone else will find this functionality useful someday.

Note that its output may be broken in multi-threaded application, as mentioned in the official documentation.