1864196 - view-source:https://discourse.mozilla.org/ takes 10 minutes+ to load and makes the tab unresponsive (70% time spent in nsLineBox::IndexOf)

Status: NEW

(Core :: Layout, defect)

Description

[Mr. Beedell, Roke Julian Lockhart (RJLB)]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/119.0

Steps to reproduce:

I visited view-source:https://discourse.mozilla.org/.

Actual results:

The browser slowed to a crawl until the tab was closed and did not ever actually load the source code.

Expected results:

The source code should have been loaded, and the tab should not have affected the rest of the browser.

Comment 1

[Mr. Beedell, Roke Julian Lockhart (RJLB)]

Attachment: view-source:https://discourse.mozilla.org/

<div class="modal-inner-container">
      <div class="modal-header">
          <button title="close" id="ember1922" class="btn-flat modal-close close btn no-text btn-icon ember-view" type="button"><svg class="fa d-icon d-icon-times svg-icon svg-string" xmlns="http://www.w3.org/2000/svg"><use xlink:href="#feather-x"></use></svg><!---->
</button>

          <div class="title">
            <h3>Create New Account</h3>

<!---->          </div>

<!---->      </div>

      <div id="modal-alert" style="display: none;"></div>

        <div id="ember1926" class="create-account ember-view">    <span id="ember1927" class="ember-view"><!----></span>
<div id="ember1928" class="has-alt-auth has-user-fields modal-body ember-view">
<!---->
<!---->
        <div class="login-form">
          <form>
            <table>
              <tbody>
                <tr class="input create-account-email">
                  <td class="label"><label for="new-account-email">Email</label></td>
                  <td>
                      <span class="value">[e-mail]</span>
                  </td>
                </tr>

                <tr class="instructions create-account-email">
                  <td></td>
                  <div id="account-email-validation" class="tip good ember-view">  <svg class="fa d-icon d-icon-check svg-icon svg-string" xmlns="http://www.w3.org/2000/svg"><use xlink:href="#feather-check"></use></svg> Your email has been authenticated by Mozilla
</div>
                  <td><label>Never shown to the public.</label></td>
                </tr>

                <tr class="input">
                  <td class="label"><label for="new-account-username">Username</label></td>
                  <td>
                      <input name="username" autocomplete="discourse" placeholder="" maxlength="50" id="new-account-username" class="ember-text-field ember-view" type="text">
                  </td>
                </tr>
                <tr class="instructions">
                  <td></td>
                  <div id="username-validation" class="tip good ember-view">  <svg class="fa d-icon d-icon-check svg-icon svg-string" xmlns="http://www.w3.org/2000/svg"><use xlink:href="#feather-check"></use></svg> Your username is available
</div>
                  <td><label>unique, no spaces, short</label></td>
                </tr>

                  <tr class="input">
                    <td class="label">
                      <label for="new-account-name">Name</label>
                    </td>
                    <td>
                        <input placeholder="" id="new-account-name" class="ember-text-field ember-view" type="text">
                    </td>
                  </tr>
                  <tr class="instructions">
                    <td></td>
                    <div id="ember1929" class="tip good ember-view"><!----></div>
                    <td><label>your full name (optional)</label></td>
                  </tr>

                <!---->

<!---->
                <tr class="password-confirmation">
                  <td><label for="new-account-password-confirmation">Password Again</label></td>
                  <td>
                    <input autocomplete="new-password" placeholder="" id="new-account-confirmation" class="ember-text-field ember-view" type="text">
                    <input placeholder="" id="new-account-challenge" class="ember-text-field ember-view" type="text">
                  </td>
                </tr>

<!---->
                <!---->
              </tbody>
            </table>

              <div class="user-fields">
                  <div id="ember1933" class="user-field text user-field-mozillians-profile ember-view"><label class="control-label" for="user-ember1933">
  Mozillians Profile
  <!---->
</label>
<div class="controls">
  <input placeholder="" maxlength="2048" id="user-ember1933" class="ember-text-field ember-view" type="text">
  <div class="instructions">link to your mozillians profile, displayed publicly (optional)</div>
</div>
</div>
              </div>
          </form>
        </div>
</div>
      <div class="modal-footer">
        <button aria-label="Create New Account" id="ember1934" class="btn-large btn-primary btn btn-text ember-view" type="button"><!----><span class="d-button-label">Create New Account<!----></span>
</button>

<!---->
        <div class="disclaimer">By registering, you agree to the <a href="https://www.mozilla.org/privacy/websites/" target="blank">privacy policy</a> and <a href="https://www.mozilla.org/about/legal/terms/mozilla/" target="blank">terms of service</a>.</div>
      </div>

      <!---->
</div>


<!---->    </div>

Comment 2

[Mr. Beedell, Roke Julian Lockhart (RJLB)]

Oops - delete that HTML please. It was meant for https://bugzilla.mozilla.org/show_bug.cgi?id=1864191#c1.

Comment 3

[Mr. Beedell, Roke Julian Lockhart (RJLB)]

Attachment: The other tabs.

Most Mozilla tabs ceased to load.

Comment 4

[Mr. Beedell, Roke Julian Lockhart (RJLB)]

Attachment: view-source:https://discourse.mozilla.org/categories on Chrome.

It works flawlessly on google-chrome-unstable-120.0.6090.0-1.src.rpm on cpe:/o:opensuse:tumbleweed:20231106.

Comment 6

[Mayank Bansal]

Profile (8 minutes, incomplete) : https://share.firefox.dev/3ugvppz
Can confirm that the view-source continued to load for >10minutes
Can repro on a build from 2019. So not a recent regression

Comment 7

[Jonathan Kew [:jfkthame]]

This sounds similar to reports such as bug 726637 and more specifically bug 727831.

Comment 8

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:TYLin, could you have a look please?

For more information, please visit BugBot documentation.

Comment 9

[Mayank Bansal]

Profile with bug 727831 fixed:
With wrapping : https://share.firefox.dev/3XetePn (truncated, took more than 1 minute after which i got bored)
Without wrapping: https://share.firefox.dev/4dERbFG (truncated, took more than 1 minute after which i got bored)

Comment 10

[Jonathan Kew [:jfkthame]]

Hmm. So the profile is no longer dominated by nsLineBox::IndexOf, so I guess that's progress. But it's still taking far too long, with a surprisingly large amount of time apparently in SVG-related stuff, and also continuation-frame management.

Comment 11

[Mayank Bansal]

HEre is a complete profile: https://share.firefox.dev/ (at 2ms sampling interval so each sample is equal to 4ms of wall clock time)
Profile from a fresh instance: https://share.firefox.dev/3MCEbEF (12m+ and then i got bored)

Comment 12

[blinky]

Regression range:
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=67d1049b0bf9&tochange=978002c0b0ad

Comment 13

[Mayank Bansal]

Proifle with latest Nightly: https://share.firefox.dev/3UpMwzu (3m+ and then I got bored)

Comment 14

[Mr. Beedell, Roke Julian Lockhart (RJLB)]

#c13

I tried to collect a profile too, but it crashed. First, my in-use tab, then the browser. about:crashes reports:

1. crash-stats.mozilla.org/report/index/89a7f789-1265-4262-a5d3-a90ee0241230
2. crash-stats.mozilla.org/report/index/26e6f774-276f-43e6-8a07-711840241230

I've uploaded a trace at bugzilla.redhat.com/show_bug.cgi?id=2334931#c0, too.

However, note that when I visit the tab, I can see part of the source. It merely stops rendering after ≈ 1s. The amount of the source I can see is dependent upon how far I can scroll during that time.