title: APScheduler python: my scheduled job is running multiple times on same timeslot
body: <pre><code>job_stores = {
                  'default': MongoDBJobStore(database=databasename,
                                             client=clientname, collection=&quot;schedulejob&quot;)
              }
              executors = {
                  'default': {'type': 'threadpool', 'max_workers': 5}
              }
              job_defaults = {
                  'coalesce': True,  # When the same task is triggered multiple times at the same time, it runs only once
                  'max_instances': 3,
                  'misfire_grace_time': 3600,  # The task is still executed after 30 seconds of expiration
              }
              global sched
              sched = BackgroundScheduler(jobstores=job_stores, executors=executors, job_defaults=job_defaults, daemon=True)
  sched.add_job(helloworld, 'interval', hours=3, args=(),
                                    name=name)
  </code></pre>
  <p>I can see schedulejob is created with single entry, but on respective timestamp, my same function helloworld got executed four times.</p>
  <p>Note: I am using Flask server with 4 nodes. Is the four nodes being the reason.</p>