BuildSeniorBackendAuto-graded

Stop a hash ring from reshuffling every key

When a node joins or leaves, almost every key moves to a different server. Make only a small share move.HashRing(nodes, vnodes=...) in ring.py should map keys to nodes so that adding or removing a node moves only about 1/N of the keys. In production every membership change sends nearly the whole cache cold, and two service instances sometimes disagree on who owns a key. Rebuild it as a ring with vnodes points per node: a key goes to the first point clockwise from its position, and the ring wraps around. Use the provided _stable_hash for every position.

45 min

python

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You're done when

Separate processes built with the same nodes map every key to the same node.
Removing a node moves only the keys that were on it. Every other key keeps its node.

What it measures

Data structures and algorithmsHow the ring and its virtual points are built, and whether a membership change only touches the node that changed.

Distributed systemsWhether you understand what lets a key-to-node mapping survive a cluster resize.

Cross-process determinismWhether the ring gives the same answer in every process and on every machine.

Your environment

Terminal + editorA full shell in the browser

Claude CodePre-authenticated, no key setup

Isolated microVMYours alone, wiped afterwards

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45 min

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