Using CheatSheets To Apply Best Practices

CheatSheet: System Design For Job Interview

CheatSheet: System Design For Job Interview

1.2 Process Of System Design

Num Name Summary
1 Outline use cases: List major and focus on some Show good sense. The questions you asked define your level
2 Estimate scale: Data + Traffic Back-of-the-envelope estimation
3 Defining data model It helps to clarify how data will flow among different components
4 Abstract design Sketch main components, explain workflow, avoid too deep for details
5 Detailed design + discussion with interviewers Explain trade-off of your proposal + on-demand deep dive
6 Identify and resolve Bottlenecks Key challenges + Trade-Offs. Usuaully no optimal solution(s)
7 Scale your design Availability, Resiliency, Scalability, Security, Serviceability, etc

1.3 Top 20 Design Problems For Technical Modules

Num Name
1 Design a distributed counter
2 Delayed task scheduling
3 Design a thread-safe Hashmap
4 Design An API Rate Limiter
5 Delayed queue
6 Design a distributed UUID generator
7 Design a distributed Hashmap
8 Design data sync for a distributed system
9 Design A big file transfer feature
10 Design a distributed transactions
11 Design: A Parking Lot Service
12 Design a distributed transaction
13 Design: A URL Redirecting Feature
14 Top URL hits
15 Unique url hits
16 Design a load balancer
17 Design a client-server API to build a rich document editor
18 Design online/offline status system
19 Design a circuit breaker
20 Design a service auto-discovery feature
21 Design a secrets management system

1.4 Top 20 Design Problems For A Complex Product

Num Name
1 Design: TinyURL – A URL Shorterner Service
2 Design Twitter News Feed
3 Design K/V DB
4 Design: Flight booking service
5 Design: Uber Backend
6 Design an API gateway
7 Design: An Elevator Service
8 Design web crawler
9 Design amazon shopping cart
10 Design: Google Suggestion Service
11 Design a payment processor
12 Design google doc
13 Design gmail
14 Design instagram, a photo sharing app
15 Design Yelp, a location-based system
16 Design Pastebin.com
17 Design amazon book recommendation system
18 Google autocomplete
19 Design Google PageRank
20 Design messaging/notification system
21 Design search post system
22 Design memcache/redis
23 Design typeahead
24 Design Google Adsense fraud detection
25 Design a voice conference system
26 Design slack

1.5 Top 30 Concepts For Feature/System Design

Num Name Summary
1 Caching Stores data so that future requests of data retrieval can be faster
2 Message Queue Provides an asynchronous communications protocol,
3 Data Partition & Sharding Break up a big data volume into many smaller parts
4 DB Indexing Create indexes on multiple columns to speed up table look up
5 DB replication Duplicate data to increase service availability
6 CAP: Consistency/Availability/Partition A distributed database system can only have 2 of the 3
7 DB: SQL & NoSQL Relational databases and non-relational databases
8 Concurrency & Communication  
9 Pessimistic And Optimistic Locking  
10 Consistency Module weak consistency, eventual consistency, strong consistency
11 Conflict resolution Quorum, vector lock, reconcile on read/write, CRDT
12 B+ Tree  
13 Networking: HTTP  
14 Pull vs Push model  
15 Garbage Collection  
16 Memory Management  
17 Heartbeats  
18 Self Protection API Rate limit, Circuit breaker, bulkhead, throttling
19 Filesystem  
20 API: gRPC vs REST  
21 Load balancer  
22 Scale up vs Scale out Vertical scaling and Horizontal scaling
23 API Design  
24 Session management  
25 Networking: TCP vs UDP  
26 Consistency patterns Weak consistency, Eventual consistency, Strong consistency
27 Availability patterns Fail-over vs Replication
28 CDN – Content Delivery Network Edge caching
29 Monitoring  
30 Security  
31 Networking: DNS  
32 Linux signals  

1.6 Top 15 Advanced Data Structure & Algorithms

Num Name Summary
1 Consistent Hash  
3 Bloom filter A space-effcient query returns either “possibly in set” or “definitely not”
4 CRDT(Conflict-Free Replicated Data Types)  
5 SSTable (Sorted Strings Table)  
6 LSM (Log Structured Merge Trees)  
7 Gossip Propagate cluster status
8 Two-phase commit/Three-phase commit  
10 Vector Clocks/Version Vectors  
11 Paxos and raft protocol  
12 Merkle Tree  

CheatSheet: Feature Design For Job Interview

1.7 Explain workflow: What happens when XXX?

Num Name Summary
1 When happens when I search in google?  
2 How loadbalancer works  
3 Explain three phase commit model  
4 Explain HTTP return code  
5 Explain Mysql DB replication model  
6 Explain gossip protocol  
7 Explain CAP  
8 Explain Hadoop file system  
9 [Linux] Explain OS booting process  
10 [Linux] What happens, when running “ls -l *”  
11 [Linux] What happens, when pressing “Ctrl + c”  

1.8 Explain tools: how XXX supports XXX?

Num Name Summary
1 How JDK implement hashmap?  
2 Explain java garbage collection model  
3 Explain raft/etcd  
4 How OS supports XXX?  

1.9 Cloud Design Principles

Num Name Summary
1 Fail fast  
2 Design for failure  
3 Immutable infrastructure  
4 Cats vs Cattle Avoid snowflake servers
5 Auto healing  
6 Async programming  
7 GitOps operational model  
8 Event-Driven Architectures  

1.10 Cloud Design Patterns

Num Name Summary
1 Ambassador pattern Create helper service to send network requests, besides the main sevice
2 Cache-Aside pattern Load data on demand into a cache from a data store
3 Circuit Breaker pattern If a request takes too many reousrce, abort it
4 Bulkhead pattern Isolate elements into pools, so that one fire won’t burn all
5 Gateway Aggregation pattern Aggregate multiple individual requests into a single request
6 Priority Queue pattern Support different SLAs for different individual clients
7 Strangler pattern Incrementally migrate a legacy system piece by piece

1.12 Grow Design Expertise In Daily Work

Num Name Summary
1 Keep the curiosity Thinking about interesting/weird questions helps
2 Deep dive into your daily work Unify and normalize problems from daily work
3 Learn the work of your coleagues Indirect working experience also help
4 Popular products under the hood Once you notice an interesting feature, think about how it’s supported?
5 Read engineering blogs Especially for big companies
6 Tools under the hood Common tools/frameworks
7 Try tools Use cases; Alternatives; Pros and Cons
8 Read papers Best practices in papers
9 Try new things Gain hands-on experience; evaluate alternatives
10 Datastore & OS Learn how databases and operating systems work
11 Language implementation Deep dive into one programming language. Java, Python, Golang, etc

1.14 Typical Trade-Off

Num Name Summary
1 Performance vs Scalability  
2 Latency vs Throughput  
3 Availability vs Consistency Brewer’s CAP theorem

1.15 Misc

Num Name Summary
1 How to store 2TB data into 3 disks of 1TB. And be tolerant for one disk failure A, B, C. And C = A XOR B
2 Find out the difference between two files. Majority of these two are the same #lcs – Longest Common Subsequence
3 How to support feature of “diff 1.txt 2. txt”  
4 Avoid double payment in a distributed payment system link


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