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I merged this PR in yesterday, finally thinking this was done https://github.com/discourse/discourse/pull/12958 but then a wild performance regression occurred. These are the problem methods:1aa20bd681/app/serializers/topic_tracking_state_serializer.rb (L13-L21)Turns out date comparison is super expensive on the backend _as well as_ the frontend. The fix was to just move the `treat_as_new_topic_start_date` into the SQL query rather than using the slower `UserOption#treat_as_new_topic_start_date` method in ruby. After this change, 1% of the total time is spent with the `created_in_new_period` comparison instead of ~20%. ---- History: Original PR which had to be reverted **https://github.com/discourse/discourse/pull/12555**. See the description there for what this PR is achieving, plus below. The issue with the original PR is addressed in92ef54f402If you went to the `x unread` link for a tag Chrome would freeze up and possibly crash, or eventually unfreeze after nearly 10 mins. Other routes for unread/new were similarly slow. From profiling the issue was the `sync` function of `topic-tracking-state.js`, which calls down to `isNew` which in turn calls `moment`, a change I had made in the PR above. The time it takes locally with ~1400 topics in the tracking state is 2.3 seconds. To solve this issue, I have moved these calculations for "created in new period" and "unread not too old" into the tracking state serializer. When I was looking at the profiler I also noticed this issue which was just compounding the problem. Every time we modify topic tracking state we recalculate the sidebar tracking/everything/tag counts. However this calls `forEachTracked` and `countTags` which can be quite expensive as they go through the whole tracking state (and were also calling the removed moment functions). I added some logs and this was being called 30 times when navigating to a new /unread route because `sync` is being called from `build-topic-route` (one for each topic loaded due to pagination). So I just added a debounce here and it makes things even faster. Finally, I changed topic tracking state to use a Map so our counts of the state keys is faster (Maps have .size whereas objects you have to do Object.keys(obj) which is O(n).) <!-- NOTE: All pull requests should have tests (rspec in Ruby, qunit in JavaScript). If your code does not include test coverage, please include an explanation of why it was omitted. -->
24 lines
637 B
Ruby
24 lines
637 B
Ruby
# frozen_string_literal: true
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class TopicTrackingStateSerializer < ApplicationSerializer
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attributes :topic_id,
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:highest_post_number,
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:last_read_post_number,
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:created_at,
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:category_id,
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:notification_level,
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:created_in_new_period,
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:unread_not_too_old,
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:treat_as_new_topic_start_date
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def created_in_new_period
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return true if !scope
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object.created_at >= treat_as_new_topic_start_date
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end
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def unread_not_too_old
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return true if object.first_unread_at.blank?
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object.updated_at >= object.first_unread_at
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end
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end
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