diff --git a/libs/apscheduler/events.py b/libs/apscheduler/events.py
index 890763eb6..016da03c5 100644
--- a/libs/apscheduler/events.py
+++ b/libs/apscheduler/events.py
@@ -3,7 +3,7 @@ __all__ = ('EVENT_SCHEDULER_STARTED', 'EVENT_SCHEDULER_SHUTDOWN', 'EVENT_SCHEDUL
            'EVENT_JOBSTORE_ADDED', 'EVENT_JOBSTORE_REMOVED', 'EVENT_ALL_JOBS_REMOVED',
            'EVENT_JOB_ADDED', 'EVENT_JOB_REMOVED', 'EVENT_JOB_MODIFIED', 'EVENT_JOB_EXECUTED',
            'EVENT_JOB_ERROR', 'EVENT_JOB_MISSED', 'EVENT_JOB_SUBMITTED', 'EVENT_JOB_MAX_INSTANCES',
-           'SchedulerEvent', 'JobEvent', 'JobExecutionEvent')
+           'SchedulerEvent', 'JobEvent', 'JobExecutionEvent', 'JobSubmissionEvent')
 
 
 EVENT_SCHEDULER_STARTED = EVENT_SCHEDULER_START = 2 ** 0
diff --git a/libs/apscheduler/executors/asyncio.py b/libs/apscheduler/executors/asyncio.py
index 5139622d1..06fc7f968 100644
--- a/libs/apscheduler/executors/asyncio.py
+++ b/libs/apscheduler/executors/asyncio.py
@@ -3,12 +3,11 @@ from __future__ import absolute_import
 import sys
 
 from apscheduler.executors.base import BaseExecutor, run_job
+from apscheduler.util import iscoroutinefunction_partial
 
 try:
-    from asyncio import iscoroutinefunction
     from apscheduler.executors.base_py3 import run_coroutine_job
 except ImportError:
-    from trollius import iscoroutinefunction
     run_coroutine_job = None
 
 
@@ -46,7 +45,7 @@ class AsyncIOExecutor(BaseExecutor):
             else:
                 self._run_job_success(job.id, events)
 
-        if iscoroutinefunction(job.func):
+        if iscoroutinefunction_partial(job.func):
             if run_coroutine_job is not None:
                 coro = run_coroutine_job(job, job._jobstore_alias, run_times, self._logger.name)
                 f = self._eventloop.create_task(coro)
diff --git a/libs/apscheduler/executors/base_py3.py b/libs/apscheduler/executors/base_py3.py
index 61abd8424..7111d2aec 100644
--- a/libs/apscheduler/executors/base_py3.py
+++ b/libs/apscheduler/executors/base_py3.py
@@ -1,5 +1,6 @@
 import logging
 import sys
+import traceback
 from datetime import datetime, timedelta
 from traceback import format_tb
 
@@ -33,6 +34,7 @@ async def run_coroutine_job(job, jobstore_alias, run_times, logger_name):
             events.append(JobExecutionEvent(EVENT_JOB_ERROR, job.id, jobstore_alias, run_time,
                                             exception=exc, traceback=formatted_tb))
             logger.exception('Job "%s" raised an exception', job)
+            traceback.clear_frames(tb)
         else:
             events.append(JobExecutionEvent(EVENT_JOB_EXECUTED, job.id, jobstore_alias, run_time,
                                             retval=retval))
diff --git a/libs/apscheduler/executors/pool.py b/libs/apscheduler/executors/pool.py
index 2f4ef455c..c85896ec2 100644
--- a/libs/apscheduler/executors/pool.py
+++ b/libs/apscheduler/executors/pool.py
@@ -3,6 +3,11 @@ import concurrent.futures
 
 from apscheduler.executors.base import BaseExecutor, run_job
 
+try:
+    from concurrent.futures.process import BrokenProcessPool
+except ImportError:
+    BrokenProcessPool = None
+
 
 class BasePoolExecutor(BaseExecutor):
     @abstractmethod
@@ -19,7 +24,13 @@ class BasePoolExecutor(BaseExecutor):
             else:
                 self._run_job_success(job.id, f.result())
 
-        f = self._pool.submit(run_job, job, job._jobstore_alias, run_times, self._logger.name)
+        try:
+            f = self._pool.submit(run_job, job, job._jobstore_alias, run_times, self._logger.name)
+        except BrokenProcessPool:
+            self._logger.warning('Process pool is broken; replacing pool with a fresh instance')
+            self._pool = self._pool.__class__(self._pool._max_workers)
+            f = self._pool.submit(run_job, job, job._jobstore_alias, run_times, self._logger.name)
+
         f.add_done_callback(callback)
 
     def shutdown(self, wait=True):
@@ -33,10 +44,13 @@ class ThreadPoolExecutor(BasePoolExecutor):
     Plugin alias: ``threadpool``
 
     :param max_workers: the maximum number of spawned threads.
+    :param pool_kwargs: dict of keyword arguments to pass to the underlying
+        ThreadPoolExecutor constructor
     """
 
-    def __init__(self, max_workers=10):
-        pool = concurrent.futures.ThreadPoolExecutor(int(max_workers))
+    def __init__(self, max_workers=10, pool_kwargs=None):
+        pool_kwargs = pool_kwargs or {}
+        pool = concurrent.futures.ThreadPoolExecutor(int(max_workers), **pool_kwargs)
         super(ThreadPoolExecutor, self).__init__(pool)
 
 
@@ -47,8 +61,11 @@ class ProcessPoolExecutor(BasePoolExecutor):
     Plugin alias: ``processpool``
 
     :param max_workers: the maximum number of spawned processes.
+    :param pool_kwargs: dict of keyword arguments to pass to the underlying
+        ProcessPoolExecutor constructor
     """
 
-    def __init__(self, max_workers=10):
-        pool = concurrent.futures.ProcessPoolExecutor(int(max_workers))
+    def __init__(self, max_workers=10, pool_kwargs=None):
+        pool_kwargs = pool_kwargs or {}
+        pool = concurrent.futures.ProcessPoolExecutor(int(max_workers), **pool_kwargs)
         super(ProcessPoolExecutor, self).__init__(pool)
diff --git a/libs/apscheduler/executors/tornado.py b/libs/apscheduler/executors/tornado.py
index a4696ce79..3b97eec92 100644
--- a/libs/apscheduler/executors/tornado.py
+++ b/libs/apscheduler/executors/tornado.py
@@ -8,10 +8,10 @@ from tornado.gen import convert_yielded
 from apscheduler.executors.base import BaseExecutor, run_job
 
 try:
-    from inspect import iscoroutinefunction
     from apscheduler.executors.base_py3 import run_coroutine_job
+    from apscheduler.util import iscoroutinefunction_partial
 except ImportError:
-    def iscoroutinefunction(func):
+    def iscoroutinefunction_partial(func):
         return False
 
 
@@ -44,7 +44,7 @@ class TornadoExecutor(BaseExecutor):
             else:
                 self._run_job_success(job.id, events)
 
-        if iscoroutinefunction(job.func):
+        if iscoroutinefunction_partial(job.func):
             f = run_coroutine_job(job, job._jobstore_alias, run_times, self._logger.name)
         else:
             f = self.executor.submit(run_job, job, job._jobstore_alias, run_times,
diff --git a/libs/apscheduler/job.py b/libs/apscheduler/job.py
index 4e24bec7a..445d9a868 100644
--- a/libs/apscheduler/job.py
+++ b/libs/apscheduler/job.py
@@ -1,4 +1,3 @@
-from collections import Iterable, Mapping
 from inspect import ismethod, isclass
 from uuid import uuid4
 
@@ -9,6 +8,11 @@ from apscheduler.util import (
     ref_to_obj, obj_to_ref, datetime_repr, repr_escape, get_callable_name, check_callable_args,
     convert_to_datetime)
 
+try:
+    from collections.abc import Iterable, Mapping
+except ImportError:
+    from collections import Iterable, Mapping
+
 
 class Job(object):
     """
@@ -24,7 +28,7 @@ class Job(object):
     :var trigger: the trigger object that controls the schedule of this job
     :var str executor: the name of the executor that will run this job
     :var int misfire_grace_time: the time (in seconds) how much this job's execution is allowed to
-        be late
+        be late (``None`` means "allow the job to run no matter how late it is")
     :var int max_instances: the maximum number of concurrently executing instances allowed for this
         job
     :var datetime.datetime next_run_time: the next scheduled run time of this job
@@ -36,7 +40,7 @@ class Job(object):
 
     __slots__ = ('_scheduler', '_jobstore_alias', 'id', 'trigger', 'executor', 'func', 'func_ref',
                  'args', 'kwargs', 'name', 'misfire_grace_time', 'coalesce', 'max_instances',
-                 'next_run_time')
+                 'next_run_time', '__weakref__')
 
     def __init__(self, scheduler, id=None, **kwargs):
         super(Job, self).__init__()
@@ -238,8 +242,9 @@ class Job(object):
 
         # Instance methods cannot survive serialization as-is, so store the "self" argument
         # explicitly
-        if ismethod(self.func) and not isclass(self.func.__self__):
-            args = (self.func.__self__,) + tuple(self.args)
+        func = self.func
+        if ismethod(func) and not isclass(func.__self__) and obj_to_ref(func) == self.func_ref:
+            args = (func.__self__,) + tuple(self.args)
         else:
             args = self.args
 
diff --git a/libs/apscheduler/jobstores/mongodb.py b/libs/apscheduler/jobstores/mongodb.py
index 7dbc3b127..ea3097ddc 100644
--- a/libs/apscheduler/jobstores/mongodb.py
+++ b/libs/apscheduler/jobstores/mongodb.py
@@ -54,7 +54,7 @@ class MongoDBJobStore(BaseJobStore):
 
     def start(self, scheduler, alias):
         super(MongoDBJobStore, self).start(scheduler, alias)
-        self.collection.ensure_index('next_run_time', sparse=True)
+        self.collection.create_index('next_run_time', sparse=True)
 
     @property
     def connection(self):
@@ -83,7 +83,7 @@ class MongoDBJobStore(BaseJobStore):
 
     def add_job(self, job):
         try:
-            self.collection.insert({
+            self.collection.insert_one({
                 '_id': job.id,
                 'next_run_time': datetime_to_utc_timestamp(job.next_run_time),
                 'job_state': Binary(pickle.dumps(job.__getstate__(), self.pickle_protocol))
@@ -96,13 +96,13 @@ class MongoDBJobStore(BaseJobStore):
             'next_run_time': datetime_to_utc_timestamp(job.next_run_time),
             'job_state': Binary(pickle.dumps(job.__getstate__(), self.pickle_protocol))
         }
-        result = self.collection.update({'_id': job.id}, {'$set': changes})
-        if result and result['n'] == 0:
+        result = self.collection.update_one({'_id': job.id}, {'$set': changes})
+        if result and result.matched_count == 0:
             raise JobLookupError(job.id)
 
     def remove_job(self, job_id):
-        result = self.collection.remove(job_id)
-        if result and result['n'] == 0:
+        result = self.collection.delete_one({'_id': job_id})
+        if result and result.deleted_count == 0:
             raise JobLookupError(job_id)
 
     def remove_all_jobs(self):
diff --git a/libs/apscheduler/jobstores/redis.py b/libs/apscheduler/jobstores/redis.py
index 61f913e9e..5bb69d635 100644
--- a/libs/apscheduler/jobstores/redis.py
+++ b/libs/apscheduler/jobstores/redis.py
@@ -14,7 +14,7 @@ except ImportError:  # pragma: nocover
     import pickle
 
 try:
-    from redis import StrictRedis
+    from redis import Redis
 except ImportError:  # pragma: nocover
     raise ImportError('RedisJobStore requires redis installed')
 
@@ -47,7 +47,7 @@ class RedisJobStore(BaseJobStore):
         self.pickle_protocol = pickle_protocol
         self.jobs_key = jobs_key
         self.run_times_key = run_times_key
-        self.redis = StrictRedis(db=int(db), **connect_args)
+        self.redis = Redis(db=int(db), **connect_args)
 
     def lookup_job(self, job_id):
         job_state = self.redis.hget(self.jobs_key, job_id)
@@ -81,7 +81,9 @@ class RedisJobStore(BaseJobStore):
             pipe.hset(self.jobs_key, job.id, pickle.dumps(job.__getstate__(),
                                                           self.pickle_protocol))
             if job.next_run_time:
-                pipe.zadd(self.run_times_key, datetime_to_utc_timestamp(job.next_run_time), job.id)
+                pipe.zadd(self.run_times_key,
+                          {job.id: datetime_to_utc_timestamp(job.next_run_time)})
+
             pipe.execute()
 
     def update_job(self, job):
@@ -92,9 +94,11 @@ class RedisJobStore(BaseJobStore):
             pipe.hset(self.jobs_key, job.id, pickle.dumps(job.__getstate__(),
                                                           self.pickle_protocol))
             if job.next_run_time:
-                pipe.zadd(self.run_times_key, datetime_to_utc_timestamp(job.next_run_time), job.id)
+                pipe.zadd(self.run_times_key,
+                          {job.id: datetime_to_utc_timestamp(job.next_run_time)})
             else:
                 pipe.zrem(self.run_times_key, job.id)
+
             pipe.execute()
 
     def remove_job(self, job_id):
diff --git a/libs/apscheduler/jobstores/rethinkdb.py b/libs/apscheduler/jobstores/rethinkdb.py
index 2185c6cc1..d8a78cde3 100644
--- a/libs/apscheduler/jobstores/rethinkdb.py
+++ b/libs/apscheduler/jobstores/rethinkdb.py
@@ -10,7 +10,7 @@ except ImportError:  # pragma: nocover
     import pickle
 
 try:
-    import rethinkdb as r
+    from rethinkdb import RethinkDB
 except ImportError:  # pragma: nocover
     raise ImportError('RethinkDBJobStore requires rethinkdb installed')
 
@@ -40,10 +40,12 @@ class RethinkDBJobStore(BaseJobStore):
             raise ValueError('The "table" parameter must not be empty')
 
         self.database = database
-        self.table = table
+        self.table_name = table
+        self.table = None
         self.client = client
         self.pickle_protocol = pickle_protocol
         self.connect_args = connect_args
+        self.r = RethinkDB()
         self.conn = None
 
     def start(self, scheduler, alias):
@@ -52,31 +54,31 @@ class RethinkDBJobStore(BaseJobStore):
         if self.client:
             self.conn = maybe_ref(self.client)
         else:
-            self.conn = r.connect(db=self.database, **self.connect_args)
+            self.conn = self.r.connect(db=self.database, **self.connect_args)
 
-        if self.database not in r.db_list().run(self.conn):
-            r.db_create(self.database).run(self.conn)
+        if self.database not in self.r.db_list().run(self.conn):
+            self.r.db_create(self.database).run(self.conn)
 
-        if self.table not in r.table_list().run(self.conn):
-            r.table_create(self.table).run(self.conn)
+        if self.table_name not in self.r.table_list().run(self.conn):
+            self.r.table_create(self.table_name).run(self.conn)
 
-        if 'next_run_time' not in r.table(self.table).index_list().run(self.conn):
-            r.table(self.table).index_create('next_run_time').run(self.conn)
+        if 'next_run_time' not in self.r.table(self.table_name).index_list().run(self.conn):
+            self.r.table(self.table_name).index_create('next_run_time').run(self.conn)
 
-        self.table = r.db(self.database).table(self.table)
+        self.table = self.r.db(self.database).table(self.table_name)
 
     def lookup_job(self, job_id):
         results = list(self.table.get_all(job_id).pluck('job_state').run(self.conn))
         return self._reconstitute_job(results[0]['job_state']) if results else None
 
     def get_due_jobs(self, now):
-        return self._get_jobs(r.row['next_run_time'] <= datetime_to_utc_timestamp(now))
+        return self._get_jobs(self.r.row['next_run_time'] <= datetime_to_utc_timestamp(now))
 
     def get_next_run_time(self):
         results = list(
             self.table
-            .filter(r.row['next_run_time'] != None)  # flake8: noqa
-            .order_by(r.asc('next_run_time'))
+            .filter(self.r.row['next_run_time'] != None)  # noqa
+            .order_by(self.r.asc('next_run_time'))
             .map(lambda x: x['next_run_time'])
             .limit(1)
             .run(self.conn)
@@ -92,7 +94,7 @@ class RethinkDBJobStore(BaseJobStore):
         job_dict = {
             'id': job.id,
             'next_run_time': datetime_to_utc_timestamp(job.next_run_time),
-            'job_state': r.binary(pickle.dumps(job.__getstate__(), self.pickle_protocol))
+            'job_state': self.r.binary(pickle.dumps(job.__getstate__(), self.pickle_protocol))
         }
         results = self.table.insert(job_dict).run(self.conn)
         if results['errors'] > 0:
@@ -101,7 +103,7 @@ class RethinkDBJobStore(BaseJobStore):
     def update_job(self, job):
         changes = {
             'next_run_time': datetime_to_utc_timestamp(job.next_run_time),
-            'job_state': r.binary(pickle.dumps(job.__getstate__(), self.pickle_protocol))
+            'job_state': self.r.binary(pickle.dumps(job.__getstate__(), self.pickle_protocol))
         }
         results = self.table.get_all(job.id).update(changes).run(self.conn)
         skipped = False in map(lambda x: results[x] == 0, results.keys())
@@ -130,20 +132,20 @@ class RethinkDBJobStore(BaseJobStore):
     def _get_jobs(self, predicate=None):
         jobs = []
         failed_job_ids = []
-        query = (self.table.filter(r.row['next_run_time'] != None).filter(predicate) if
-                 predicate else self.table)
+        query = (self.table.filter(self.r.row['next_run_time'] != None).filter(predicate)  # noqa
+                 if predicate else self.table)
         query = query.order_by('next_run_time', 'id').pluck('id', 'job_state')
 
         for document in query.run(self.conn):
             try:
                 jobs.append(self._reconstitute_job(document['job_state']))
-            except:
+            except Exception:
                 self._logger.exception('Unable to restore job "%s" -- removing it', document['id'])
                 failed_job_ids.append(document['id'])
 
         # Remove all the jobs we failed to restore
         if failed_job_ids:
-            r.expr(failed_job_ids).for_each(
+            self.r.expr(failed_job_ids).for_each(
                 lambda job_id: self.table.get_all(job_id).delete()).run(self.conn)
 
         return jobs
diff --git a/libs/apscheduler/jobstores/sqlalchemy.py b/libs/apscheduler/jobstores/sqlalchemy.py
index beb27fb56..dcfd3e565 100644
--- a/libs/apscheduler/jobstores/sqlalchemy.py
+++ b/libs/apscheduler/jobstores/sqlalchemy.py
@@ -11,7 +11,7 @@ except ImportError:  # pragma: nocover
 
 try:
     from sqlalchemy import (
-        create_engine, Table, Column, MetaData, Unicode, Float, LargeBinary, select)
+        create_engine, Table, Column, MetaData, Unicode, Float, LargeBinary, select, and_)
     from sqlalchemy.exc import IntegrityError
     from sqlalchemy.sql.expression import null
 except ImportError:  # pragma: nocover
@@ -106,7 +106,7 @@ class SQLAlchemyJobStore(BaseJobStore):
         }).where(self.jobs_t.c.id == job.id)
         result = self.engine.execute(update)
         if result.rowcount == 0:
-            raise JobLookupError(id)
+            raise JobLookupError(job.id)
 
     def remove_job(self, job_id):
         delete = self.jobs_t.delete().where(self.jobs_t.c.id == job_id)
@@ -134,7 +134,7 @@ class SQLAlchemyJobStore(BaseJobStore):
         jobs = []
         selectable = select([self.jobs_t.c.id, self.jobs_t.c.job_state]).\
             order_by(self.jobs_t.c.next_run_time)
-        selectable = selectable.where(*conditions) if conditions else selectable
+        selectable = selectable.where(and_(*conditions)) if conditions else selectable
         failed_job_ids = set()
         for row in self.engine.execute(selectable):
             try:
diff --git a/libs/apscheduler/jobstores/zookeeper.py b/libs/apscheduler/jobstores/zookeeper.py
index 2cca83e8f..525306936 100644
--- a/libs/apscheduler/jobstores/zookeeper.py
+++ b/libs/apscheduler/jobstores/zookeeper.py
@@ -1,6 +1,5 @@
 from __future__ import absolute_import
 
-import os
 from datetime import datetime
 
 from pytz import utc
@@ -65,7 +64,7 @@ class ZooKeeperJobStore(BaseJobStore):
 
     def lookup_job(self, job_id):
         self._ensure_paths()
-        node_path = os.path.join(self.path, job_id)
+        node_path = self.path + "/" + str(job_id)
         try:
             content, _ = self.client.get(node_path)
             doc = pickle.loads(content)
@@ -92,7 +91,7 @@ class ZooKeeperJobStore(BaseJobStore):
 
     def add_job(self, job):
         self._ensure_paths()
-        node_path = os.path.join(self.path,  str(job.id))
+        node_path = self.path + "/" + str(job.id)
         value = {
             'next_run_time': datetime_to_utc_timestamp(job.next_run_time),
             'job_state': job.__getstate__()
@@ -105,7 +104,7 @@ class ZooKeeperJobStore(BaseJobStore):
 
     def update_job(self, job):
         self._ensure_paths()
-        node_path = os.path.join(self.path,  str(job.id))
+        node_path = self.path + "/" + str(job.id)
         changes = {
             'next_run_time': datetime_to_utc_timestamp(job.next_run_time),
             'job_state': job.__getstate__()
@@ -118,7 +117,7 @@ class ZooKeeperJobStore(BaseJobStore):
 
     def remove_job(self, job_id):
         self._ensure_paths()
-        node_path = os.path.join(self.path,  str(job_id))
+        node_path = self.path + "/" + str(job_id)
         try:
             self.client.delete(node_path)
         except NoNodeError:
@@ -151,7 +150,7 @@ class ZooKeeperJobStore(BaseJobStore):
         all_ids = self.client.get_children(self.path)
         for node_name in all_ids:
             try:
-                node_path = os.path.join(self.path, node_name)
+                node_path = self.path + "/" + node_name
                 content, _ = self.client.get(node_path)
                 doc = pickle.loads(content)
                 job_def = {
diff --git a/libs/apscheduler/schedulers/asyncio.py b/libs/apscheduler/schedulers/asyncio.py
index 289ef13fe..70ebedeb6 100644
--- a/libs/apscheduler/schedulers/asyncio.py
+++ b/libs/apscheduler/schedulers/asyncio.py
@@ -38,13 +38,19 @@ class AsyncIOScheduler(BaseScheduler):
     _eventloop = None
     _timeout = None
 
+    def start(self, paused=False):
+        if not self._eventloop:
+            self._eventloop = asyncio.get_event_loop()
+
+        super(AsyncIOScheduler, self).start(paused)
+
     @run_in_event_loop
     def shutdown(self, wait=True):
         super(AsyncIOScheduler, self).shutdown(wait)
         self._stop_timer()
 
     def _configure(self, config):
-        self._eventloop = maybe_ref(config.pop('event_loop', None)) or asyncio.get_event_loop()
+        self._eventloop = maybe_ref(config.pop('event_loop', None))
         super(AsyncIOScheduler, self)._configure(config)
 
     def _start_timer(self, wait_seconds):
diff --git a/libs/apscheduler/schedulers/background.py b/libs/apscheduler/schedulers/background.py
index 03f29822a..bb8f77da2 100644
--- a/libs/apscheduler/schedulers/background.py
+++ b/libs/apscheduler/schedulers/background.py
@@ -29,7 +29,9 @@ class BackgroundScheduler(BlockingScheduler):
         super(BackgroundScheduler, self)._configure(config)
 
     def start(self, *args, **kwargs):
-        self._event = Event()
+        if self._event is None or self._event.is_set():
+            self._event = Event()
+
         BaseScheduler.start(self, *args, **kwargs)
         self._thread = Thread(target=self._main_loop, name='APScheduler')
         self._thread.daemon = self._daemon
diff --git a/libs/apscheduler/schedulers/base.py b/libs/apscheduler/schedulers/base.py
index 8f910a653..3dfb74377 100644
--- a/libs/apscheduler/schedulers/base.py
+++ b/libs/apscheduler/schedulers/base.py
@@ -1,7 +1,6 @@
 from __future__ import print_function
 
 from abc import ABCMeta, abstractmethod
-from collections import MutableMapping
 from threading import RLock
 from datetime import datetime, timedelta
 from logging import getLogger
@@ -27,6 +26,11 @@ from apscheduler.events import (
     EVENT_JOB_ADDED, EVENT_EXECUTOR_ADDED, EVENT_EXECUTOR_REMOVED, EVENT_ALL_JOBS_REMOVED,
     EVENT_JOB_SUBMITTED, EVENT_JOB_MAX_INSTANCES, EVENT_SCHEDULER_RESUMED, EVENT_SCHEDULER_PAUSED)
 
+try:
+    from collections.abc import MutableMapping
+except ImportError:
+    from collections import MutableMapping
+
 #: constant indicating a scheduler's stopped state
 STATE_STOPPED = 0
 #: constant indicating a scheduler's running state (started and processing jobs)
@@ -82,6 +86,11 @@ class BaseScheduler(six.with_metaclass(ABCMeta)):
         self.state = STATE_STOPPED
         self.configure(gconfig, **options)
 
+    def __getstate__(self):
+        raise TypeError("Schedulers cannot be serialized. Ensure that you are not passing a "
+                        "scheduler instance as an argument to a job, or scheduling an instance "
+                        "method where the instance contains a scheduler as an attribute.")
+
     def configure(self, gconfig={}, prefix='apscheduler.', **options):
         """
         Reconfigures the scheduler with the given options.
@@ -398,7 +407,7 @@ class BaseScheduler(six.with_metaclass(ABCMeta)):
         :param str|unicode id: explicit identifier for the job (for modifying it later)
         :param str|unicode name: textual description of the job
         :param int misfire_grace_time: seconds after the designated runtime that the job is still
-            allowed to be run
+            allowed to be run (or ``None`` to allow the job to run no matter how late it is)
         :param bool coalesce: run once instead of many times if the scheduler determines that the
             job should be run more than once in succession
         :param int max_instances: maximum number of concurrently running instances allowed for this
@@ -594,14 +603,13 @@ class BaseScheduler(six.with_metaclass(ABCMeta)):
         """
         jobstore_alias = None
         with self._jobstores_lock:
+            # Check if the job is among the pending jobs
             if self.state == STATE_STOPPED:
-                # Check if the job is among the pending jobs
-                if self.state == STATE_STOPPED:
-                    for i, (job, alias, replace_existing) in enumerate(self._pending_jobs):
-                        if job.id == job_id and jobstore in (None, alias):
-                            del self._pending_jobs[i]
-                            jobstore_alias = alias
-                            break
+                for i, (job, alias, replace_existing) in enumerate(self._pending_jobs):
+                    if job.id == job_id and jobstore in (None, alias):
+                        del self._pending_jobs[i]
+                        jobstore_alias = alias
+                        break
             else:
                 # Otherwise, try to remove it from each store until it succeeds or we run out of
                 # stores to check
diff --git a/libs/apscheduler/schedulers/blocking.py b/libs/apscheduler/schedulers/blocking.py
index e61715757..4ecc9f6f1 100644
--- a/libs/apscheduler/schedulers/blocking.py
+++ b/libs/apscheduler/schedulers/blocking.py
@@ -14,7 +14,9 @@ class BlockingScheduler(BaseScheduler):
     _event = None
 
     def start(self, *args, **kwargs):
-        self._event = Event()
+        if self._event is None or self._event.is_set():
+            self._event = Event()
+
         super(BlockingScheduler, self).start(*args, **kwargs)
         self._main_loop()
 
diff --git a/libs/apscheduler/schedulers/qt.py b/libs/apscheduler/schedulers/qt.py
index 6ee5d332a..dda77d796 100644
--- a/libs/apscheduler/schedulers/qt.py
+++ b/libs/apscheduler/schedulers/qt.py
@@ -9,9 +9,13 @@ except (ImportError, RuntimeError):  # pragma: nocover
         from PyQt4.QtCore import QObject, QTimer
     except ImportError:
         try:
-            from PySide.QtCore import QObject, QTimer  # flake8: noqa
+            from PySide2.QtCore import QObject, QTimer  # noqa
         except ImportError:
-            raise ImportError('QtScheduler requires either PyQt5, PyQt4 or PySide installed')
+            try:
+                from PySide.QtCore import QObject, QTimer  # noqa
+            except ImportError:
+                raise ImportError('QtScheduler requires either PyQt5, PyQt4, PySide2 '
+                                  'or PySide installed')
 
 
 class QtScheduler(BaseScheduler):
@@ -26,7 +30,8 @@ class QtScheduler(BaseScheduler):
     def _start_timer(self, wait_seconds):
         self._stop_timer()
         if wait_seconds is not None:
-            self._timer = QTimer.singleShot(wait_seconds * 1000, self._process_jobs)
+            wait_time = min(wait_seconds * 1000, 2147483647)
+            self._timer = QTimer.singleShot(wait_time, self._process_jobs)
 
     def _stop_timer(self):
         if self._timer:
diff --git a/libs/apscheduler/triggers/base.py b/libs/apscheduler/triggers/base.py
index ce2526a88..55d010dba 100644
--- a/libs/apscheduler/triggers/base.py
+++ b/libs/apscheduler/triggers/base.py
@@ -22,27 +22,16 @@ class BaseTrigger(six.with_metaclass(ABCMeta)):
 
     def _apply_jitter(self, next_fire_time, jitter, now):
         """
-        Randomize ``next_fire_time`` by adding or subtracting a random value (the jitter). If the
-        resulting datetime is in the past, returns the initial ``next_fire_time`` without jitter.
-
-        ``next_fire_time - jitter <= result <= next_fire_time + jitter``
+        Randomize ``next_fire_time`` by adding a random value (the jitter).
 
         :param datetime.datetime|None next_fire_time: next fire time without jitter applied. If
             ``None``, returns ``None``.
-        :param int|None jitter: maximum number of seconds to add or subtract to
-            ``next_fire_time``. If ``None`` or ``0``, returns ``next_fire_time``
+        :param int|None jitter: maximum number of seconds to add to ``next_fire_time``
+            (if ``None`` or ``0``, returns ``next_fire_time``)
         :param datetime.datetime now: current datetime
         :return datetime.datetime|None: next fire time with a jitter.
         """
         if next_fire_time is None or not jitter:
             return next_fire_time
 
-        next_fire_time_with_jitter = next_fire_time + timedelta(
-                seconds=random.uniform(-jitter, jitter))
-
-        if next_fire_time_with_jitter < now:
-            # Next fire time with jitter is in the past.
-            # Ignore jitter to avoid false misfire.
-            return next_fire_time
-
-        return next_fire_time_with_jitter
+        return next_fire_time + timedelta(seconds=random.uniform(0, jitter))
diff --git a/libs/apscheduler/triggers/combining.py b/libs/apscheduler/triggers/combining.py
index 64f83011a..bb9000618 100644
--- a/libs/apscheduler/triggers/combining.py
+++ b/libs/apscheduler/triggers/combining.py
@@ -45,7 +45,7 @@ class AndTrigger(BaseCombiningTrigger):
     Trigger alias: ``and``
 
     :param list triggers: triggers to combine
-    :param int|None jitter: advance or delay the job execution by ``jitter`` seconds at most.
+    :param int|None jitter: delay the job execution by ``jitter`` seconds at most
     """
 
     __slots__ = ()
@@ -73,7 +73,7 @@ class OrTrigger(BaseCombiningTrigger):
     Trigger alias: ``or``
 
     :param list triggers: triggers to combine
-    :param int|None jitter: advance or delay the job execution by ``jitter`` seconds at most.
+    :param int|None jitter: delay the job execution by ``jitter`` seconds at most
 
     .. note:: Triggers that depends on the previous fire time, such as the interval trigger, may
         seem to behave strangely since they are always passed the previous fire time produced by
diff --git a/libs/apscheduler/triggers/cron/__init__.py b/libs/apscheduler/triggers/cron/__init__.py
index ce675dd93..fec6e3b5c 100644
--- a/libs/apscheduler/triggers/cron/__init__.py
+++ b/libs/apscheduler/triggers/cron/__init__.py
@@ -16,7 +16,7 @@ class CronTrigger(BaseTrigger):
 
     :param int|str year: 4-digit year
     :param int|str month: month (1-12)
-    :param int|str day: day of the (1-31)
+    :param int|str day: day of month (1-31)
     :param int|str week: ISO week (1-53)
     :param int|str day_of_week: number or name of weekday (0-6 or mon,tue,wed,thu,fri,sat,sun)
     :param int|str hour: hour (0-23)
@@ -26,7 +26,7 @@ class CronTrigger(BaseTrigger):
     :param datetime|str end_date: latest possible date/time to trigger on (inclusive)
     :param datetime.tzinfo|str timezone: time zone to use for the date/time calculations (defaults
         to scheduler timezone)
-    :param int|None jitter: advance or delay the job execution by ``jitter`` seconds at most.
+    :param int|None jitter: delay the job execution by ``jitter`` seconds at most
 
     .. note:: The first weekday is always **monday**.
     """
diff --git a/libs/apscheduler/triggers/interval.py b/libs/apscheduler/triggers/interval.py
index 831ba3830..61094aa13 100644
--- a/libs/apscheduler/triggers/interval.py
+++ b/libs/apscheduler/triggers/interval.py
@@ -20,7 +20,7 @@ class IntervalTrigger(BaseTrigger):
     :param datetime|str start_date: starting point for the interval calculation
     :param datetime|str end_date: latest possible date/time to trigger on
     :param datetime.tzinfo|str timezone: time zone to use for the date/time calculations
-    :param int|None jitter: advance or delay the job execution by ``jitter`` seconds at most.
+    :param int|None jitter: delay the job execution by ``jitter`` seconds at most
     """
 
     __slots__ = 'timezone', 'start_date', 'end_date', 'interval', 'interval_length', 'jitter'
diff --git a/libs/apscheduler/util.py b/libs/apscheduler/util.py
index 3c48e550b..1e643bffa 100644
--- a/libs/apscheduler/util.py
+++ b/libs/apscheduler/util.py
@@ -5,8 +5,9 @@ from __future__ import division
 from datetime import date, datetime, time, timedelta, tzinfo
 from calendar import timegm
 from functools import partial
-from inspect import isclass
+from inspect import isclass, ismethod
 import re
+import sys
 
 from pytz import timezone, utc, FixedOffset
 import six
@@ -21,6 +22,15 @@ try:
 except ImportError:
     TIMEOUT_MAX = 4294967  # Maximum value accepted by Event.wait() on Windows
 
+try:
+    from asyncio import iscoroutinefunction
+except ImportError:
+    try:
+        from trollius import iscoroutinefunction
+    except ImportError:
+        def iscoroutinefunction(func):
+            return False
+
 __all__ = ('asint', 'asbool', 'astimezone', 'convert_to_datetime', 'datetime_to_utc_timestamp',
            'utc_timestamp_to_datetime', 'timedelta_seconds', 'datetime_ceil', 'get_callable_name',
            'obj_to_ref', 'ref_to_obj', 'maybe_ref', 'repr_escape', 'check_callable_args',
@@ -263,7 +273,18 @@ def obj_to_ref(obj):
     if '<locals>' in name:
         raise ValueError('Cannot create a reference to a nested function')
 
-    return '%s:%s' % (obj.__module__, name)
+    if ismethod(obj):
+        if hasattr(obj, 'im_self') and obj.im_self:
+            # bound method
+            module = obj.im_self.__module__
+        elif hasattr(obj, 'im_class') and obj.im_class:
+            # unbound method
+            module = obj.im_class.__module__
+        else:
+            module = obj.__module__
+    else:
+        module = obj.__module__
+    return '%s:%s' % (module, name)
 
 
 def ref_to_obj(ref):
@@ -332,7 +353,10 @@ def check_callable_args(func, args, kwargs):
     has_varargs = has_var_kwargs = False
 
     try:
-        sig = signature(func)
+        if sys.version_info >= (3, 5):
+            sig = signature(func, follow_wrapped=False)
+        else:
+            sig = signature(func)
     except ValueError:
         # signature() doesn't work against every kind of callable
         return
@@ -398,3 +422,12 @@ def check_callable_args(func, args, kwargs):
         raise ValueError(
             'The target callable does not accept the following keyword arguments: %s' %
             ', '.join(unmatched_kwargs))
+
+
+def iscoroutinefunction_partial(f):
+    while isinstance(f, partial):
+        f = f.func
+
+    # The asyncio version of iscoroutinefunction includes testing for @coroutine
+    # decorations vs. the inspect version which does not.
+    return iscoroutinefunction(f)
diff --git a/libs/version.txt b/libs/version.txt
index a0f180af6..07101175f 100644
--- a/libs/version.txt
+++ b/libs/version.txt
@@ -1,5 +1,5 @@
 apprise=0.8.8
-apscheduler=3.5.1
+apscheduler=3.8.0
 babelfish=0.5.5
 backports.functools-lru-cache=1.5
 Beaker=1.10.0