All Patterns

46 production-proven patterns organized by category. Each one has interactive visualization, multi-language implementations, exercises, and precise source links.

Data Structures

Pattern	One-Liner	Sources
Bitmask	Pack N flags into one integer, O(1) test any combo	React, Linux
Min Heap	O(1) peek at highest priority, O(log n) push/pop	React, Linux CFS
Ring Buffer	Fixed-size FIFO, wraps around, zero allocation	LMAX, Linux
Trie	O(k) prefix lookup, shared prefixes share nodes	Linux FIB, Redis
Skip List	Probabilistic O(log n) sorted structure	Redis, LevelDB
Bloom Filter	Probabilistic set membership, zero false negatives	LevelDB, Chromium
LRU Cache	Evict least recently used, O(1) get/put	groupcache, Linux
B+ Tree	High-branching tree, leaf-linked for range scans	PostgreSQL, SQLite
Tagged Union	Type tag + union for safe multi-type dispatch	Godot, PyTorch
Merkle Tree	Hash upward for O(log n) integrity proof	Git, ZFS
Merge Iterator	K-way merge via min-heap	LevelDB, RocksDB

Concurrency

Pattern	One-Liner	Sources
Semaphore	Counter limits concurrent access	Linux, Go
Actor Model	Private state + mailbox, no shared memory	Akka, Erlang
Work Stealing	Idle threads steal from busy queues	Go, Tokio
MVCC	Versioned rows let readers never block writers	PostgreSQL, etcd
Cooperative Scheduling	Yield between work chunks to stay responsive	React, Go
Double Buffering	Swap two copies for atomic update	React Fiber, GPU
Backpressure	Slow producer when consumer can't keep up	Node.js, Reactive
Event Loop	Single-threaded I/O multiplexing	libuv, Redis
Logical Clock	Order events without wall-clock time	etcd, LevelDB

System

Pattern	One-Liner	Sources
Circuit Breaker	Stop calling failing services, fail fast	Hystrix, gobreaker
Rate Limiter	Token bucket controls throughput	Go, Nginx
Retry with Backoff	Exponential delay + jitter on failure	K8s, gRPC
Write-Ahead Log	Log changes before applying, crash-safe	etcd, PostgreSQL
Batch Processing	Accumulate ops, execute as group	Kafka, React
Consistent Hashing	Add/remove nodes remaps ~1/n keys	groupcache, HAProxy
Dependency Graph	DAG + topological sort	Cargo, pnpm
Middleware Chain	Composable pre/post handlers	gRPC, Koa
Registry	Self-register by name, discover at runtime	TensorFlow, gRPC
Dirty Flag	Recompute only when marked changed	Chromium, React
LSM Tree	Buffer writes in memory, flush sorted to disk	LevelDB, RocksDB
Checkpointing	Periodic snapshot, recover from checkpoint	PostgreSQL, Redis

Memory

Pattern	One-Liner	Sources
Object Pool	Pre-allocate and reuse to skip GC	Go sync.Pool, Godot
Flyweight	Share identical immutable objects	Python int cache, V8
Arena Allocator	Bump-allocate in region, free all at once	bumpalo, Go
Free List	O(1) alloc/free via linked freed slots	Go runtime, Linux
Copy-on-Write	Share by reference, copy on mutation	Git, Rust Cow
Reference Counting	Auto-cleanup at zero owners	CPython, Rust Arc
Tombstone	Mark deleted, reclaim later	LevelDB, Cassandra
Interning	Deduplicate immutable values, pointer equality	Rust compiler, CPython

Behavioral

Pattern	One-Liner	Sources
State Machine	Explicit states, impossible transitions unrepresentable	XState, Linux TCP
Observer	Subscribe to events, decouple producer/consumer	EventEmitter, Redux
Iterator	Lazy sequences, zero intermediate allocations	Rust, Python
Diff / Patch	Compute minimal changes between two states	React, Git
Vtable	Function pointer struct for polymorphism	Linux kernel, CPython
Visitor	Dispatch type-specific callbacks on tree nodes	LLVM, Vue