How to configure Sidekiq for specialized or large-scale GitLab instances

What this post added

This post details how to configure Sidekiq for specialized or large-scale GitLab instances. It covers identifying pain points through metrics (e.g., `sidekiq_queue_size`, `sidekiq_running_jobs`), monitoring Redis CPU usage, and customizing Sidekiq configurations. The recommended approach is to use routing rules and one-queue-per-shard for better clarity and reduced Redis load. It provides examples of using queue selectors to dedicate processing power to specific queues like `project_export` and discusses the trade-offs between queue selectors and routing rules.