Challenge #2: Unique ID Generation

In this challenge, you’ll need to implement a globally-unique ID generation system that runs against Maelstrom’s unique-ids workload. Your service should be totally available, meaning that it can continue to operate even in the face of network partitions.


RPC: generate

Your node will receive a request message body that looks like this:

  "type": "generate"

and it will need to return a "generate_ok" message with a unique ID:

  "type": "generate_ok",
  "id": 123

The msg_id and in_reply_to fields have been removed for clarity but they exist as described in the previous challenge. IDs may be of any type–strings, booleans, integers, floats, arrays, etc.


Build your node binary as maelstrom-unique-ids and run it against Maelstrom with the following command:

./maelstrom test -w unique-ids --bin ~/go/bin/maelstrom-unique-ids --time-limit 30 --rate 1000 --node-count 3 --availability total --nemesis partition

This will run a 3-node cluster for 30 seconds and request new IDs at the rate of 1000 requests per second. It checks for total availability and will induce network partitions during the test. It will also verify that all IDs are unique.

If you see an “Everything looks good” message, congrats! Continue on to the Broadcast challenge. If you’re having trouble, ask for help on the Community forum.

  1. Read More About Echo
  2. Read More About Unique ID Generation
  3. Read More About Broadcast
  4. Read More About Grow-Only Counter
  5. Read More About Kafka-Style Log
  6. Read More About Totally-Available Transactions