fun executeOn(executorService: ExecutorService) {
      client.dispatcher.assertLockNotHeld()

      var success = false
      try {
        executorService.execute(this)
        success = true
      } catch (e: RejectedExecutionException) {
        failRejected(e)
      } finally {
        if (!success) {
          client.dispatcher.finished(this) // This call is no longer running!
        }
      }
    }