Debugging Performance Issues with a Rails API Response Time in a React Frontend
I'm not sure how to approach This might be a silly question, but Currently developing a React frontend that communicates with a Rails API, I’ve noticed that some API responses are noticeably slow, affecting the user experience... In particular, a call to fetch user data takes about 3 seconds, which is not acceptable for our application’s performance standards. After profiling the API endpoints using Skylight, I found that the bottleneck appears to be in one of the controller actions. For instance, the code for fetching user details looks like this: ```ruby class UsersController < ApplicationController def show @user = User.includes(:posts).find(params[:id]) render json: @user, include: :posts end end ``` While using `includes` should ideally help with eager loading, I suspect that the problem might actually be stemming from the large number of associated posts. I’ve tried switching to `select` to limit the fields returned, but that didn't yield much improvement: ```ruby @user = User.select(:id, :name).includes(:posts).find(params[:id]) ``` I also experimented with pagination on the posts to further limit the data sent back: ```ruby @user = User.includes(posts: { page: params[:page] }).find(params[:id]) ``` None of these approaches seem to resolve the core performance issue, and the response time remains high. I’ve also considered whether the JSON serialization is contributing to the slowness, so I looked into `ActiveModel::Serializers`. After implementing it, the controller action now looks like this: ```ruby class UserSerializer < ActiveModel::Serializer attributes :id, :name, :posts end ``` Still, the speed didn’t improve significantly. Another angle I’m pondering is whether the database indexes on the `posts` table are optimized for the lookups being performed. I currently have indexes on `user_id`, but perhaps I need to revisit the overall database design. Has anyone tackled similar performance issues between a Rails API and a frontend application? What strategies or tools did you find effective in diagnosing and resolving these kinds of latency problems? Any insight into potential optimizations or overlooked aspects would be immensely helpful! For context: I'm using Ruby on Linux. Thanks in advance! This is part of a larger web app I'm building. Am I missing something obvious? I'm developing on Linux with Ruby. I've been using Ruby for about a year now. What's the best practice here?