core async reseting experiment

experiment.clj

(ns io.chouser.experiment
  (:require [clojure.core.async :as async]))

(defn bang []
  (future
    (dotimes [i 10]
      (async/go
        (print (str "start " i "\n")) (flush)
        (Thread/sleep 20000)
        (prn :done i)))))

(require '[clojure.core.async.impl.dispatch :as impl.d]
         '[clojure.core.async.impl.exec.threadpool :as tp])
(import '(java.util.concurrent ThreadPoolExecutor))

(defn new-dispath-executor [_]
  (delay (tp/thread-pool-executor #(.set ^ThreadLocal @#'impl.d/in-dispatch true))))

(defn reset-dispatch-executor []
  (let [old-executor ^ThreadPoolExecutor @impl.d/executor
        executor-svc-field (doto (.getDeclaredField (type old-executor) "executor_svc")
                                 (.setAccessible true))
        thread-pool-executor (.get executor-svc-field old-executor)]
    (prn :largest (.getLargestPoolSize thread-pool-executor) :active (.getActiveCount thread-pool-executor))
    (prn :shutdown (.shutdownNow thread-pool-executor))
    (alter-var-root #'impl.d/executor new-dispath-executor)))