github.com/jbramsden/hugo@v0.47.1/docs/content/en/troubleshooting/build-performance.md (about)

     1  ---
     2  title: Build Performance
     3  linktitle: Build Performance
     4  description: An overview of features used for diagnosing and improving performance issues in site builds.
     5  date: 2017-03-12
     6  publishdate: 2017-03-12
     7  lastmod: 2017-03-12
     8  keywords: [performance, build]
     9  categories: [troubleshooting]
    10  menu:
    11    docs:
    12      parent: "troubleshooting"
    13  weight: 3
    14  slug:
    15  aliases: []
    16  toc: true
    17  ---
    18  
    19  {{% note %}}
    20  The example site used below is from https://github.com/gohugoio/hugo/tree/master/examples/blog
    21  {{% /note %}}
    22  
    23  ## Template Metrics
    24  
    25  Hugo is a very fast static site generator, but it is possible to write
    26  inefficient templates.  Hugo's *template metrics* feature is extremely helpful
    27  in pinpointing which templates are executed most often and how long those
    28  executions take **in terms of CPU time**.
    29  
    30  | Metric Name         | Description |
    31  |---------------------|-------------|
    32  | cumulative duration | The cumulative time spent executing a given template. |
    33  | average duration    | The average time spent executing a given template. |
    34  | maximum duration    | The maximum time a single execution took for a given template. |
    35  | count               | The number of times a template was executed. |
    36  | template            | The template name. |
    37  
    38  ```
    39  ▶ hugo --templateMetrics
    40  Started building sites ...
    41  
    42  Built site for language en:
    43  0 draft content
    44  0 future content
    45  0 expired content
    46  2 regular pages created
    47  22 other pages created
    48  0 non-page files copied
    49  0 paginator pages created
    50  4 tags created
    51  3 categories created
    52  total in 18 ms
    53  
    54  Template Metrics:
    55  
    56       cumulative       average       maximum
    57         duration      duration      duration  count  template
    58       ----------      --------      --------  -----  --------
    59       6.419663ms     583.605µs     994.374µs     11  _internal/_default/rss.xml
    60       4.718511ms    1.572837ms    3.880742ms      3  indexes/category.html
    61       4.642666ms    2.321333ms    3.282842ms      2  post/single.html
    62       4.364445ms     396.767µs    2.451372ms     11  partials/header.html
    63       2.346069ms     586.517µs     903.343µs      4  indexes/tag.html
    64       2.330919ms     211.901µs    2.281342ms     11  partials/header.includes.html
    65       1.238976ms     103.248µs     446.084µs     12  post/li.html
    66         972.16µs      972.16µs      972.16µs      1  _internal/_default/sitemap.xml
    67        953.597µs     953.597µs     953.597µs      1  index.html
    68        822.263µs     822.263µs     822.263µs      1  indexes/post.html
    69        567.498µs       51.59µs     112.205µs     11  partials/navbar.html
    70         348.22µs      31.656µs      88.249µs     11  partials/meta.html
    71        346.782µs     173.391µs     276.176µs      2  post/summary.html
    72        235.184µs       21.38µs     124.383µs     11  partials/footer.copyright.html
    73        132.003µs          12µs     117.999µs     11  partials/menu.html
    74         72.547µs       6.595µs      63.764µs     11  partials/footer.html
    75  ```
    76  
    77  {{% note %}}
    78  **A Note About Parallelism**
    79  
    80  Hugo builds pages in parallel where multiple pages are generated
    81  simultaneously. Because of this parallelism, the sum of "cumulative duration"
    82  values is usually greater than the actual time it takes to build a site.
    83  {{% /note %}}
    84  
    85  
    86  ## Cached Partials
    87  
    88  Some `partial` templates such as sidebars or menus are executed many times
    89  during a site build.  Depending on the content within the `partial` template and
    90  the desired output, the template may benefit from caching to reduce the number
    91  of executions.  The [`partialCached`][partialCached] template function provides
    92  caching capabilities for `partial` templates.
    93  
    94  {{% tip %}}
    95  Note that you can create cached variants of each `partial` by passing additional
    96  parameters to `partialCached` beyond the initial context.  See the
    97  `partialCached` documentation for more details.
    98  {{% /tip %}}
    99  
   100  
   101  ## Step Analysis
   102  
   103  Hugo provides a means of seeing metrics about each step in the site build
   104  process.  We call that *Step Analysis*.  The *step analysis* output shows the
   105  total time per step, the cumulative time after each step (in parentheses),
   106  the memory usage per step, and the total memory allocations per step.
   107  
   108  To enable *step analysis*, use the `--stepAnalysis` option when running Hugo.
   109  
   110  
   111  [partialCached]:{{< ref "/functions/partialCached.md" >}}