Unexpected Maelstrome error for maelstrom-unique-ids challenge

Questions / Help
1

Hello! My friends and I are trying to work through the challenges at Challenge #2: Unique ID Generation · Fly Docs and we’re stuck on the second problem:

Code:

package main

import (
	"log"

	"github.com/google/uuid"
	maelstrom "github.com/jepsen-io/maelstrom/demo/go"
)

func main() {
	n := maelstrom.NewNode()

	n.Handle("generate", func(msg maelstrom.Message) error {
		var body map[string]any = make(map[string]any)
		// if err := json.Unmarshal(msg.Body, &body); err != nil {
		// 	return err
		// }

		id := uuid.New().String()
		body["type"] = "generate_ok"
		body["id"] = id

		return n.Reply(msg, body)
	})

	if err := n.Run(); err != nil {
		log.Fatal(err)
	}
}

We’re getting this error:

WARN [2023-02-22 15:38:55,267] jepsen test runner - jepsen.core Test crashed!
clojure.lang.ExceptionInfo: Node n2 crashed with exit status 1. Before crashing, it wrote to STDOUT:

{"src":"n2","dest":"c1","body":{"in_reply_to":1,"type":"init_ok"}}

And to STDERR:

2023/02/22 15:38:24 Received {c1 n2 {"type":"init","node_id":"n2","node_ids":["n0","n1","n2"],"msg_id":1}}
2023/02/22 15:38:24 Node n2 initialized
2023/02/22 15:38:24 Sent {"src":"n2","dest":"c1","body":{"in_reply_to":1,"type":"init_ok"}}
2023/02/22 15:38:24 Received {c7 n2 {"type":"generate","msg_id":1}}
2023/02/22 15:38:24 No handler for {"id":8,"src":"c7","dest":"n2","body":{"type":"generate","msg_id":1}}

Full STDERR logs are available in /Users/bkane/Code/dist-sys/maelstrom/store/unique-ids/20230222T153822.085-0800/node-logs/n2.log

Tthe STDERR logs mentioned above contain:

2023/02/22 15:38:24 Received {c1 n2 {"type":"init","node_id":"n2","node_ids":["n0","n1","n2"],"msg_id":1}}
2023/02/22 15:38:24 Node n2 initialized
2023/02/22 15:38:24 Sent {"src":"n2","dest":"c1","body":{"in_reply_to":1,"type":"init_ok"}}
2023/02/22 15:38:24 Received {c7 n2 {"type":"generate","msg_id":1}}
2023/02/22 15:38:24 No handler for {"id":8,"src":"c7","dest":"n2","body":{"type":"generate","msg_id":1}}

However, when we run the code locally and type in the JSON, we get the expected response:

$ go run .
{"id":8,"src":"c7","dest":"n2","body":{"type":"generate","msg_id":1}}
2023/02/22 15:54:55 Received {c7 n2 {"type":"generate","msg_id":1}}
2023/02/22 15:54:55 Sent {"dest":"c7","body":{"id":"95fd3289-550e-467f-9f6d-0c55d76142b8","in_reply_to":1,"type":"generate_ok"}}
{"dest":"c7","body":{"id":"95fd3289-550e-467f-9f6d-0c55d76142b8","in_reply_to":1,"type":"generate_ok"}}

Is there somethng obvious we’re doing incorrectly? We’re new to both distributed systems and Go. Thank you!

2

That looks quite fine to me. The only think I can think is that perhaps you missed the go install . step before running maelstrom?

2 Likes
3

Yes, that was it. Thank you @craigpastro!!

1 Like