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Lessons (35)

• Resources, QoS and Scheduling Control

  How the scheduler decides where pods run, and how requests, limits, affinity, taints and disruption budgets shape it …

• Kubernetes Cluster Architecture, Simply

  … it stores the requested configuration and status. Scheduler Chooses a worker node for a new pod. Controllers Watch …

• Design a Polite Web Crawler

  … normalize, deduplicate and schedule per host. The problem in context A search product wants to crawl 100 million …

• Go Concurrency: Goroutines, Channels and Context

  Concurrency vs parallelism, goroutines and the scheduler, buffered and unbuffered channels, select, WaitGroup, Mutex and atomics, worker pools …

• StatefulSets, DaemonSets, Jobs and CronJobs

  … a Job on a schedule yaml apiVersion: batch/v1 kind: CronJob metadata: name: nightly-report spec: schedule: "0 …

• Concurrency, Resilience & Distributed Workflows

  … Idempotency is required for retryable HTTP requests, queue consumers, scheduled jobs and webhook handlers. Retries, exponential backoff and …

• L6 Production Debugging Casebook

  … One scheduled job on three pods Without coordination, three reports are dispatched : each pod starts its own scheduler …

• Heaps & Priority Queues

  … The engine behind "top K" problems, schedulers and Dijkstra. The big idea In a hospital emergency room, patients …

• Extending Kubernetes: CRDs, Operators and Admission

  … object required: [schedule, target] properties: schedule: { type: string } target: { type: string } retention: type: integer minimum: 1 default: 7 …

• Cost Optimization and the Well-Architected Framework

  … 7 } }] } Databases - Use Aurora Serverless v2 or schedule stop for dev databases; delete old manual snapshots. - DynamoDB: pick …

• Distributed Coordination: Consensus, Heartbeats and Gossip

  … Observe term changes, quorum loss and fencing rejections. Check your understanding What happens when the scheduler uses only …

• Internals, Upgrades, Resilience and Interview Questions

  … The scheduler binds each Pod to a node, and the kubelet starts the containers. 2. Liveness vs readiness …

• CI/CD and Reviewed Production Changes

  … Configure the scheduler to handle 2 as a drift signal rather than an execution failure. Alert an owner …

• Pods: Where Your App Actually Runs

  … cpu: "250m" a quarter of one CPU core for scheduling memory: "256Mi" limits: memory: "512Mi" do not use …

• Containers at Scale: ECS Deep Dive and EKS

  … inspect scheduling events, resource requests, node capacity, availability-zone constraints, and available subnet addresses. Requests guide placement; limits …

• Stacks & Queues

  … Two simple structures behind undo buttons, browser history, task scheduling and many interview problems. The big idea ![A …

• Capacity Planning, SLOs and Error Budgets

  … It is not permission to schedule 22 minutes of downtime: short, repeated failures consume the same budget. Define …

• Serverless Architecture

  … JSON.stringify(result) }; }; When to use it ✅ Spiky or unpredictable traffic, event processing (uploads, queues, webhooks), scheduled jobs …

• Event-Driven Patterns, Step Functions and Reliable Lambdas

  … and filtering Routing events between services, SaaS and schedules Kinesis / MSK Ordered streams High-throughput, replayable streams Step …

• Batch vs Stream and Data Modeling

  … Build reporting tables in scheduled batches or incremental jobs. Denormalize read models deliberately and retain lineage back to …

• Data in Microservices: Sagas & the Outbox Pattern

  … Release stock 3 Charge card Refund card 4 Schedule shipment (last step: nothing after it can fail) ⚠️ Compensation …

• Deployments: Keep Your App Running

  … as a migration CronJob A Job on a schedule, such as a nightly report For a beginner web …

• Design a Social Media Feed

  … Store each post durably before scheduling fan-out. Precompute inbox entries for ordinary authors using bounded workers. 2 …

• Troubleshooting Playbook

  … Status by status Pending The pod is not scheduled. describe shows why. Event message Cause Fix --- --- --- Insufficient cpu …

• Debug Latency Like an Investigator

  … subset. Every morning Batch reports, backup, cache expiry, scheduled work. Restart helps briefly Warm cache, leak, churn, periodic …

• Practical Project: Deploy a Real CRM App on EKS

  … Worker nodes and scheduling The EKS control plane does not run your pods. A node group needs running …

• Linked Lists

  … linked list + hash map), undo stacks, OS task scheduling. Technique 1: Traverse js function toArray(head) { const values …

• Production Capstone and Interview Practice

  … Add scheduled drift detection with explicit handling of exit code 2. Step 5: rehearse recovery and cleanup Change …

• Backend Languages: Node.js, Go, Python & Rust

  … thousands of goroutines"] S{{Go scheduler}} -- G1[goroutine] & G2[goroutine] & G3[goroutine] & G4[goroutine …] S -- C1[CPU core …

• Frontend Performance & Core Web Vitals

  … tasks: yield to the browser between chunks ( await scheduler.yield() or setTimeout ). - Move heavy work off the main …

• AWS Security Building Blocks

  … Do not disable or schedule deletion of a shared encryption key just to clean up a tutorial. Further …

• Structural Patterns: How to Connect Objects

  … card, cart.total); const shipment = await this.shipping.schedule(cart.items, customer.address); await this.mailer.sendConfirmation(customer …

• 500 Users Upload Documents at Once: Design the Background Job Pipeline

  … one-page uploads Per-user quota and fair scheduling One tenant cannot occupy every worker Bounded queue and …

• Backend Design Scenarios

  … For the hot region: - pre-warm a minimum capacity shortly before the event; - use scheduled scaling for the …

• Caching & Redis

  … and aggregations Durable and queryable; refresh on a schedule or after events Use a public cache only when …