mirror of
https://github.com/twitter/the-algorithm.git
synced 2024-12-22 12:51:40 +03:00
103 lines
4.3 KiB
Markdown
103 lines
4.3 KiB
Markdown
|
Home Mixer
|
||
|
|
==========
|
||
|
|
|
||
|
|
Home Mixer is the main service used to construct and serve Twitter's Home Timelines. It currently
|
||
|
|
powers:
|
||
|
|
- For you - best Tweets from people you follow + recommended out-of-network content
|
||
|
|
- Following - reverse chronological Tweets from people you follow
|
||
|
|
- Lists - reverse chronological Tweets from List members
|
||
|
|
|
||
|
|
Home Mixer is built on Product Mixer, our custom Scala framework that facilitates building
|
||
|
|
feeds of content.
|
||
|
|
|
||
|
|
## Overview
|
||
|
|
|
||
|
|
The For You recommendation algorithm in Home Mixer involves the following stages:
|
||
|
|
|
||
|
|
- Candidate Generation - fetch Tweets from various Candidate Sources. For example:
|
||
|
|
- Earlybird Search Index
|
||
|
|
- User Tweet Entity Graph
|
||
|
|
- Cr Mixer
|
||
|
|
- Follow Recommendations Service
|
||
|
|
- Feature Hydration
|
||
|
|
- Fetch the ~6000 features needed for ranking
|
||
|
|
- Scoring and Ranking using ML model
|
||
|
|
- Filters and Heuristics. For example:
|
||
|
|
- Author Diversity
|
||
|
|
- Content Balance (In network vs Out of Network)
|
||
|
|
- Feedback fatigue
|
||
|
|
- Deduplication / previously seen Tweets removal
|
||
|
|
- Visibility Filtering (blocked, muted authors/tweets, NSFW settings)
|
||
|
|
- Mixing - integrate Tweets with non-Tweet content
|
||
|
|
- Ads
|
||
|
|
- Who-to-follow modules
|
||
|
|
- Prompts
|
||
|
|
- Product Features and Serving
|
||
|
|
- Conversation Modules for replies
|
||
|
|
- Social Context
|
||
|
|
- Timeline Navigation
|
||
|
|
- Edited Tweets
|
||
|
|
- Feedback options
|
||
|
|
- Pagination and cursoring
|
||
|
|
- Observability and logging
|
||
|
|
- Client instructions and content marshalling
|
||
|
|
|
||
|
|
## Pipeline Structure
|
||
|
|
|
||
|
|
### General
|
||
|
|
|
||
|
|
Product Mixer services like Home Mixer are structured around Pipelines that split the execution
|
||
|
|
into transparent and structured steps.
|
||
|
|
|
||
|
|
Requests first go to Product Pipelines, which are used to select which Mixer Pipeline or
|
||
|
|
Recommendation Pipeline to run for a given request. Each Mixer or Recommendation
|
||
|
|
Pipeline may run multiple Candidate Pipelines to fetch candidates to include in the response.
|
||
|
|
|
||
|
|
Mixer Pipelines combine the results of multiple heterogeneous Candidate Pipelines together
|
||
|
|
(e.g. ads, tweets, users) while Recommendation Pipelines are used to score (via Scoring Pipelines)
|
||
|
|
and rank the results of homogenous Candidate Pipelines so that the top ranked ones can be returned.
|
||
|
|
These pipelines also marshall candidates into a domain object and then into a transport object
|
||
|
|
to return to the caller.
|
||
|
|
|
||
|
|
Candidate Pipelines fetch candidates from underlying Candidate Sources and perform some basic
|
||
|
|
operations on the Candidates, such as filtering out unwanted candidates, applying decorations,
|
||
|
|
and hydrating features.
|
||
|
|
|
||
|
|
The sections below describe the high level pipeline structure (non-exhaustive) for the main Home
|
||
|
|
Timeline tabs powered by Home Mixer.
|
||
|
|
|
||
|
|
### For You
|
||
|
|
|
||
|
|
- ForYouProductPipelineConfig
|
||
|
|
- ForYouScoredTweetsMixerPipelineConfig (main orchestration layer - mixes Tweets with ads and users)
|
||
|
|
- ForYouScoredTweetsCandidatePipelineConfig (fetch Tweets)
|
||
|
|
- ScoredTweetsRecommendationPipelineConfig (main Tweet recommendation layer)
|
||
|
|
- Fetch Tweet Candidates
|
||
|
|
- ScoredTweetsInNetworkCandidatePipelineConfig
|
||
|
|
- ScoredTweetsCrMixerCandidatePipelineConfig
|
||
|
|
- ScoredTweetsUtegCandidatePipelineConfig
|
||
|
|
- ScoredTweetsFrsCandidatePipelineConfig
|
||
|
|
- Feature Hydration and Scoring
|
||
|
|
- ScoredTweetsScoringPipelineConfig
|
||
|
|
- ForYouConversationServiceCandidatePipelineConfig (backup reverse chron pipeline in case Scored Tweets fails)
|
||
|
|
- ForYouAdsCandidatePipelineConfig (fetch ads)
|
||
|
|
- ForYouWhoToFollowCandidatePipelineConfig (fetch users to recommend)
|
||
|
|
|
||
|
|
### Following
|
||
|
|
|
||
|
|
- FollowingProductPipelineConfig
|
||
|
|
- FollowingMixerPipelineConfig
|
||
|
|
- FollowingEarlybirdCandidatePipelineConfig (fetch tweets from Search Index)
|
||
|
|
- ConversationServiceCandidatePipelineConfig (fetch ancestors for conversation modules)
|
||
|
|
- FollowingAdsCandidatePipelineConfig (fetch ads)
|
||
|
|
- FollowingWhoToFollowCandidatePipelineConfig (fetch users to recommend)
|
||
|
|
|
||
|
|
### Lists
|
||
|
|
|
||
|
|
- ListTweetsProductPipelineConfig
|
||
|
|
- ListTweetsMixerPipelineConfig
|
||
|
|
- ListTweetsTimelineServiceCandidatePipelineConfig (fetch tweets from timeline service)
|
||
|
|
- ConversationServiceCandidatePipelineConfig (fetch ancestors for conversation modules)
|
||
|
|
- ListTweetsAdsCandidatePipelineConfig (fetch ads)
|
||
|
|
|