System design patterns
Sharding, load balancing, CAP tradeoffs, and scaling patterns — interview and production ready.
Implement a Consistent Hash Ring in Python
Build a minimal consistent hash ring with virtual nodes to map keys to servers stably as nodes are added or removed.
import hashlib
import bisect
class ConsistentHashRing:
def __init__(self, nodes=None, replicas=3):
self.replicas = replicas
self.ring = {}
self.sorted_keys = []
if nodes:
for node in nodes:
self.add_node(node)
def _hash(self, key):
return i…Round Robin Load Balancer in Python
This code simulates round robin load balancing by distributing a list of requests evenly across a list of servers.
def round_robin_servers(requests: list[str], servers: list[str]) -> dict[str, list[str]]:
assignments = {server: [] for server in servers}
for idx, request in enumerate(requests):
server = servers[idx % len(servers)]
assignments[server].append(request)
return assignments
if __name__ == "_…Browse by section
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System design patterns — Python code examples
What you will find here
This page collects system design patterns snippets — short, copy-ready Python you can paste into our free online IDE and run without installing anything. Each sample includes a plain-English explanation and the full source code.
Samples vs tutorials and challenges
Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.