ensemble

Jobs distribution and orchestration as a library for Clojure

:dependencies [
  [com.aboutecho.ensemble/ensemble "0.1.6"]
]

Jobs distribution

Ensemble uses ZooKeeper to coordinate, so you'll need one installed.

(require '[com.aboutecho.ensemble :as ensemble])

(declare stop-all start-all)

(let [cluster (ensemble/join-cluster {
                :url   "zk://zookeeper.local:2181"
                :ns    "/echo-ensemble"
                :name  "peer32" })
      jobs    (ensemble/peer-jobs cluster)]
  (add-watch jobs :state-change
    (fn [_ _ old new]
      (stop-all old)
      (start-all new)))
  (start-all @jobs)
  ...
  (ensemble/leave-cluster cluster))

Jobs execution

Ensemble can execute long-running tasks in separate Thread and supervise them to stay alive and not stall.

(require '[com.aboutecho.ensemble.process :as process])

(declare on-data)

(process/supervise
  (fn []
    (let [stream (clj-http/get "https://stream.twitter.com" :as stream)]
      (process/add-finalizer #(.close stream))
      (loop []
        (on-data (.readLine stream))
        (process/heartbeat)
        (recur))))
  { :name "twitter-stream" 
    :threshold  40000 })
...
(process/stop-supervisor sup)

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