diff --git a/promise/__init__.py b/promise/__init__.py
index ba52dbb..af77281 100644
--- a/promise/__init__.py
+++ b/promise/__init__.py
@@ -15,6 +15,25 @@
 __version__ = get_version(VERSION)
 
 if not __SETUP__:
-    from .promise import Promise, promise_for_dict, promisify, is_thenable, async_instance
+    from .promise import (
+        Promise,
+        promise_for_dict,
+        promisify,
+        is_thenable,
+        async_instance,
+        get_default_scheduler,
+        set_default_scheduler
+    )
+    from .scheduler import SyncScheduler, ThreadScheduler
 
-    __all__ = ['Promise', 'promise_for_dict', 'promisify', 'is_thenable', 'async_instance']
+    __all__ = [
+        'Promise',
+        'promise_for_dict',
+        'promisify',
+        'is_thenable',
+        'async_instance',
+        'get_default_scheduler',
+        'set_default_scheduler',
+        'SyncScheduler',
+        'ThreadScheduler'
+    ]
diff --git a/promise/async_.py b/promise/async_.py
index 87494e8..db71669 100644
--- a/promise/async_.py
+++ b/promise/async_.py
@@ -1,32 +1,5 @@
-# from threading import Timer, Thread
-
+# Based on https://github.com/petkaantonov/bluebird/blob/master/src/promise.js
 from .compat import Queue
-# from .context import Context
-
-# Based on https://github.com/petkaantonov/bluebird/blob/master/src/async.js
-
-
-class Scheduler(object):
-
-    def call(self, fn):
-        # thread = Thread(target=fn)
-        # thread = Timer(0.01, fn)
-        # fn = thread.start
-        try:
-            # c = Context.peek_context()
-            # if not c:
-            fn()
-            # else:
-            #     c.on_exit(fn)
-        except:
-            pass
-        # thread = Thread(target=fn)
-        # thread = Timer(0.001, fn)
-        # thread.start()
-
-
-def get_default_scheduler():
-    return Scheduler()
 
 
 # https://docs.python.org/2/library/queue.html#Queue.Queue
@@ -36,13 +9,13 @@ def get_default_scheduler():
 
 class Async(object):
 
-    def __init__(self, schedule=None):
+    def __init__(self, schedule):
         self.is_tick_used = False
         self.late_queue = Queue(LATE_QUEUE_CAPACITY)
         self.normal_queue = Queue(NORMAL_QUEUE_CAPACITY)
         self.have_drained_queues = False
         self.trampoline_enabled = True
-        self.schedule = schedule or get_default_scheduler()
+        self.schedule = schedule
 
     def enable_trampoline(self):
         self.trampoline_enabled = True
diff --git a/promise/promise.py b/promise/promise.py
index e0970c9..527a144 100644
--- a/promise/promise.py
+++ b/promise/promise.py
@@ -12,8 +12,18 @@
 from .utils import deprecated, integer_types, string_types, text_type, binary_type
 from .context import Context
 from .promise_list import PromiseList
+from .scheduler import SyncScheduler
+
+async_instance = Async(SyncScheduler())
+
+
+def get_default_scheduler():
+    return async_instance.scheduler
+
+
+def set_default_scheduler(scheduler):
+    async_instance.scheduler = scheduler
 
-async_instance = Async()
 
 IS_PYTHON2 = version_info[0] == 2
 DEFAULT_TIMEOUT = None  # type: float
diff --git a/promise/scheduler.py b/promise/scheduler.py
new file mode 100644
index 0000000..015a909
--- /dev/null
+++ b/promise/scheduler.py
@@ -0,0 +1,15 @@
+from threading import Thread
+
+
+class SyncScheduler(object):
+    def call(self, fn):
+        try:
+            fn()
+        except:
+            pass
+
+
+class ThreadScheduler(object):
+    def call(self, fn):
+        thread = Thread(target=fn)
+        thread.start()