DOMLocalization can cause attribute churn by removing and re-adding attributes with the same value they had before removal

[bgrins]

I noticed this when looking into perf in https://bugzilla.mozilla.org/show_bug.cgi?id=1448213. We occasionally hit a case where an attribute gets removed and then re-added with the same value: https://searchfox.org/mozilla-central/rev/8848b9741fc4ee4e9bc3ae83ea0fc048da39979f/intl/l10n/DOMLocalization.jsm#170-189. This can cause issues where, for instance, we underline an accesskey in a label, and then un-underline it, and then re-underline it to the same value.

I notice this happens on <button id="useCurrentBtn"> in about:preferences as an example.

[stasm]

Thanks for filing this here. Would it help if we compared the existing values of localizable attributes before setting new values, or is there anything more to keep in mind here?

[bgrins]

I think comparing existing values would be enough.

[asurkov]

I noticed this when looking into perf in https://bugzilla.mozilla.org/show_bug.cgi?id=1448213. We occasionally hit a case where an attribute gets removed and then re-added with the same value: https://searchfox.org/mozilla-central/rev/8848b9741fc4ee4e9bc3ae83ea0fc048da39979f/intl/l10n/DOMLocalization.jsm#170-189.

@bgrins do you say that overlayAttributes is called for no-change? I assume that @data-l10n-attrs is pretty static, i.e. never changed once set.

[bgrins]

See https://bugzilla.mozilla.org/show_bug.cgi?id=1534480, which has a patch that handles both data-l10n-attrs and individual attributes in overlayAttributes.

[Pike]

Is this fixed by #354 ? @zbraniecki ?

[zbraniecki]

yes!