ruby-on-rails - 使用 Wicked_PDF gem 在 Rails 中生成 PDF 时的高 CPU 使用率

Question

我正在尝试使用 Rails 生成 PDF 文件，但当我这样做时，我注意到我的系统 CPU 开始用尽。最初，它会从 ~2.5% 上升到 ~65%-$80% 一段稳定的时间，然后最后几乎在我的页面上的 iframe 中显示 PDF 之前达到最大值。以下是我在监视系统内存使用情况时收到的一些消息:

Warning or critical alerts (lasts 9 entries)
                          2017-06-09 14:58:07 (0:00:04) - CRITICAL on CPU_SYSTEM (100.0)
                          2017-06-09 14:58:04 (0:00:13) - CRITICAL on CPU_USER (Min:72.8 Mean:83.3 Max:93.7)
                          2017-06-09 14:47:39 (0:00:06) - CRITICAL on CPU_USER (93.0)
                          2017-06-09 14:47:29 (0:00:04) - WARNING on CPU_SYSTEM (74.7)
                          2017-06-09 14:36:48 (0:00:04) - CRITICAL on CPU_SYSTEM (100.0)
                          2017-06-09 14:36:45 (0:00:10) - CRITICAL on CPU_IOWAIT (Min:78.6 Mean:85.7 Max:97.4)
                          2017-06-09 14:18:06 (0:00:04) - CRITICAL on CPU_SYSTEM (94.3)
                          2017-06-09 14:18:06 (0:00:07) - CRITICAL on CPU_USER (91.0)
2017-06-09 15:01:14       2017-06-09 14:17:44 (0:00:04) - WARNING on CPU_SYSTEM (73.8)

我为生成 PDF 安装的 gem 是 wicked_pdf (1.0.6) 和 wkhtmltopdf-binary-edge (0.12.4.0)。并且每个过程的代码如下:

controllers/concerns/pdf_player_reports.rb

def director_report_pdf
  @players = Player.where(id: params["player_ids"]

  respond_to do |format|
  format.html
  format.pdf do
    render pdf: "#{params['pdf_title']}",
      template: 'players/director_summary_report.pdf.erb',
        layout: 'print',
        show_as_html: params.key?('debug'),
        window_status: 'Loading...',
        disable_internal_links: true,
        disable_external_links: true,
        dpi: 75,
        disable_javascript: true,
        :margin => {:top => 7, :bottom  => 7, :left => 6, :right => 0},
        encoding: 'utf8'
  end
end

players/director_summary_report.pdf.erb

<div class="document" style="margin-top: -63px;">
  <% @players.each do |player| %>
     <% reports = player.reports.order(created_at: :desc) %>
     <% if player.is_college_player? %>
       <%= render partial: 'college_director_report.html.erb', player: player %>
     <% else %>
       <%= render partial: 'pro_director_report.html.erb', player: player %>
     <% end %>
     <%= "<div class='page-break'></div>".html_safe %>
  <% end %>
</div>

college_director_report.html.erb

<%= wicked_pdf_stylesheet_link_tag "application", media: "all" %>
<%= wicked_pdf_javascript_include_tag "application" %>
<% provide(:title, "#{player.football_name}") %>
<% self.formats = [:html, :pdf, :css, :coffee, :scss] %>

<style>
    thead { display: table-row-group; page-break-inside: avoid }
    tfoot { display: table-row-group; }
    /*thead:before, thead:after { display: none; }*/
    table { page-break-inside: avoid; }
    tr { page-break-inside: avoid; }
    .page-break {
        display:block; clear:both; page-break-after:always;
    }
    .keep-together { page-break-before: always !important; }
    .table-striped>tbody>tr:nth-child(odd)>td,
    tr.found{
        background-color:#e2e0e0 !important;
    }
</style>

<div class="row">
    <div class="col-xs-6">
        <span>DIRECTOR SUMMARY</span>
    </div>
    <div class="col-xs-6 text-right">
        <%= "#{player.full_name} / #{player.school.short_name}".upcase %>
        <h1><%= "#{player.full_name(true)} (#{player.school.code})".upcase %></h1>
    </div>
</div>

<div class="row">
  <div class="col-xs-12">
    <%= render 'directors_report_player_header', player: player %>
    <%= render 'directors_report_workouts', player: player %>
    <%= render 'directors_report_grades', player: player %>
    <%= render 'legacy_directors_report_contacts', player: player %>
  </div>
</div>

directors_report_player_header.html.erb

<table class="table table-condensed table-bordered">
    <thead>
        <tr>
            <th>Name</th>
            <th>School</th>
            <th>#</th>
            <th>Position</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td><%= player.full_name(true) %></td>
            <td><%= player.school.short_name %></td>
            <td><%= player.jersey %></td>
            <td><%= player.position.abbreviation %></td>
        </tr>
    </tbody>
</table>

更新

我使用以下命令运行了一个示例 PDF 生成器，CPU% 最终达到最大值，如下所示...

 <table class="table table-condensed">
    <thead>
      <th>Number</th>
    </thead>
    <tbody>
      <% (1..60000).each do |number| %>
        <tr>
          <td><%= number %></td>
        </tr>
      <% end %>
    </tbody>
  </table>

Answer 1

将此放在 Controller 中似乎是不明智的，因为在您部署此请求的那一刻，请求将花费大量时间来生成和阻止对其他页面的其他传入请求。

您应该将其分为两个问题。一个生成 HTML 的作业(可以是这个 Controller )，然后是一个将 HTML 转换为 PDF 格式的后台任务。

在您的 Controller 中，使用 DelayedJob 或类似工具触发作业，然后呈现一个页面以轮询已完成的作业。

然后在您的后台作业中，您只处理将 HTML 呈现为 PDF 的任务，而不是在 Web 请求中。沿着这些线的东西:

class RendersReportPdf
  def self.call player_ids
    html = ReportsController.render :director_report_pdf, assigns: { players: Player.where(id: player_ids }
    pdf = WickedPdf.new.pdf_from_string html    
    temp = Tempfile.new("#{Time.now.to_i}.pdf")
    temp.write(pdf)
    temp.close
    temp.path
    # Probably upload this to S3 or similar at this point
    # Notify the user that it's now available somehow
  end
end

如果您这样做，那么您可以排除问题是在您的 Controller 操作中运行 WickedPDF，而且您还可以确保您的站点在您有长时间运行的请求时保持正常运行。