django-apscheduler 任务计划问题咨询

我使用了这个框架的 django-apscheduler

代码内容

# -*- coding: utf-8 -*-
import datetime
import time
from apscheduler.schedulers.background import BackgroundScheduler
from django_apscheduler.jobstores import DjangoJobStore, register_events, register_job
from apscheduler.executors.pool import ThreadPoolExecutor, ProcessPoolExecutor

executors = {
        'default': ThreadPoolExecutor(10),
        'processpool': ProcessPoolExecutor(3)
    }
scheduler = BackgroundScheduler(executors=executors)
scheduler.add_jobstore(DjangoJobStore(), 'default')


def cron_test():
    print '当前时间：{0}'.format(datetime.datetime.now())

def cron_task(run_time):
    task_idss = str(time.time())
    print task_idss
    scheduler.add_job(func=cron_test, next_run_time=run_time, id=task_idss)
    scheduler.start()

在 django 的一个 view 里面调用

class GameOpenTimeView(View):
    def post(self, request, obj_id):
        print obj_id
        open_time = request.POST.get("open_time")
        print open_time
        open_time = datetime.datetime.strptime(open_time,"%Y-%m-%d %H:%M:00")
        print type(open_time)
        print open_time
        cron_task(open_time)
        return JsonResponse({'status': 'success'})

时间由前端页面传入

问题

当我第一次传一个时间进入，可以正常生成一个任务点

当我第二次传入一个时间，出现告警说

    return self.dispatch(request, *args, **kwargs)
  File "/Users/apple/OneDrive/Code_7zGame/Envs/tdops/lib/python2.7/site-packages/django/views/generic/base.py", line 88, in dispatch
    return handler(request, *args, **kwargs)
  File "/Users/apple/OneDrive/vultr_svn/Django_myself/tdops/pro1/views.py", line 340, in post
    cron_task(open_time)
  File "/Users/apple/OneDrive/vultr_svn/Django_myself/tdops/opsbase/schedwork.py", line 23, in cron_task
    scheduler.start()
  File "/Users/apple/OneDrive/Code_7zGame/Envs/tdops/lib/python2.7/site-packages/apscheduler/schedulers/background.py", line 33, in start
    BaseScheduler.start(self, *args, **kwargs)
  File "/Users/apple/OneDrive/Code_7zGame/Envs/tdops/lib/python2.7/site-packages/apscheduler/schedulers/base.py", line 134, in start
    raise SchedulerAlreadyRunningError
SchedulerAlreadyRunningError: Scheduler is already running
[04/Sep/2018 20:53:21] "POST /pro1/gameopentime/1003/ HTTP/1.1" 500 18550

这个是为何，这个模块之前也是有用过，也没出现这样当情况，不过之前是直接使用了 apscheduler 模块然后后面也有换成了 apscheduler 模块试过，也是一样情况的

正常不是一个任务就一个 scheduler.start() 的么,为何不给再起一个的。