Problem with the uberjar after upgrading from 3.7.0 to 4.0.0

[bvsn]

Hello.

I had a problem when I upgraded my langohr dependency from 3.7.0 to 4.0.0. I can't run lein uberjar anymore because it hangs up.

(ns core
  (:require [langohr.core :as lc]
            [langohr.channel :as lch]))


(def conn (lc/connect {:host "127.0.0.1"
                       :port 5672
                       :vhost "/"}}))

(def ch (lch/open conn))


(defn publish
  [payload queue]
  (lb/publish channel queue queue payload {:content-type "text/plain"}))

To fix it I moved my connection inside the publish function. But I think that it's a bad solution to create and close so much TCP connections.

My project.clj

(defproject some "0.1.0"
  :description "FIXME: write description"
  :url "http://example.com/FIXME"
  :license {:name "Eclipse Public License"
            :url "http://www.eclipse.org/legal/epl-v10.html"}

  :dependencies [[org.clojure/clojure "1.8.0"]
                 [cheshire "5.7.1"]

                 [compojure "1.6.0"]
                 [ring-cors "0.1.10"]
                 [ring/ring-core "1.6.1"]
                 [ring/ring-devel "1.6.1"]
                 [org.immutant/web "2.1.8"]
                 [com.novemberain/langohr "3.7.0"]

                 [com.novemberain/welle "3.0.0"]]

  :profiles {:uberjar {:aot :all
                       :omit-source true
                       :uberjar-name "some.jar"}}

  :main core)

[michaelklishin]

Please use mailing list for questions in the future.

Your problem is that you open a connection in top level namespace code. Any potentially blocking operation will block the compiler.

You want to use Component or a similar library that makes it easier to initialise dependencies and store them in application-wide state without using top level namespace code.

[michaelklishin]

Also Component will make it easy to reset system state, e.g. between tests, while with connections stored in vars all your options (alter-var-root and such) are hacky and introduce mutable shared state.