diff --git a/.gitignore b/.gitignore
index cf05cfd5..f3d430d7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,3 +19,4 @@ MANIFEST
 .venv
 redis/
 */_build/
+build/*
diff --git a/.travis.yml b/.travis.yml
index 281d95e5..cc13970d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,6 @@
 language: python
 python:
   - 2.7
-  - 3.4
   - 3.5
   - 3.6
 env:
@@ -14,8 +13,6 @@ matrix:
       env: DJANGO_VERSION='>=2.0,<2.1'
     - python: 2.7
       env: DJANGO_VERSION='>=2.1,<2.2'
-    - python: 3.4
-      env: DJANGO_VERSION='>=2.1,<2.2'
 # command to run tests
 install: ./install_redis.sh
 script: make test DJANGO_VERSION=$DJANGO_VERSION
diff --git a/README.rst b/README.rst
index 2b795746..607a40ac 100644
--- a/README.rst
+++ b/README.rst
@@ -21,6 +21,16 @@ Docs can be found at http://django-redis-cache.readthedocs.org/en/latest/.
 Changelog
 =========
 
+2.0.0
+-----
+
+* Adds support for redis-py >= 3.0.
+* Drops support for Redis 2.6.
+* Drops support for Python 3.4.
+* Removes custom ``expire`` method in lieu of Django's ``touch``.
+* Removes ``CacheKey`` in favor of string literals.
+
+
 1.8.0
 -----
 
diff --git a/docs/api.rst b/docs/api.rst
index 0f733059..9ea77209 100644
--- a/docs/api.rst
+++ b/docs/api.rst
@@ -93,6 +93,13 @@ Standard Django Cache API
     :param version: Version of key
     :type version: Integer or None
 
+.. function:: touch(self, key, timeout):
+
+    Updates the timeout on a key.
+
+    :param key: Location of the value
+    :rtype: bool
+
 
 
 Cache Methods Provided by django-redis-cache
@@ -124,14 +131,22 @@ Cache Methods Provided by django-redis-cache
     :param version: Version of the keys
 
 
-.. function:: get_or_set(self, key, func[, timeout=None]):
+.. function:: get_or_set(self, key, func[, timeout=None, lock_timeout=None, stale_cache_timeout=None]):
+
+    Get a value from the cache or call ``func`` to set it and return it.
 
-    Retrieves a key value from the cache and sets the value if it does not exist.
+    This implementation is slightly more advanced that Django's.  It provides thundering herd
+    protection, which prevents multiple threads/processes from calling the value-generating
+    function at the same time.
 
     :param key: Location of the value
     :param func: Callable used to set the value if key does not exist.
-    :param timeout: Number of seconds to hold value in cache.
+    :param timeout: Time in seconds that value at key is considered fresh.
     :type timeout: Number of seconds or None
+    :param lock_timeout: Time in seconds that the lock will stay active and prevent other threads from acquiring the lock.
+    :type lock_timeout: Number of seconds or None
+    :param stale_cache_timeout: Time in seconds that the stale cache will remain after the key has expired. If ``None`` is specified, the stale value will remain indefinitely.
+    :type stale_cache_timeout: Number of seconds or None
 
 
 .. function:: reinsert_keys(self):
@@ -147,12 +162,9 @@ Cache Methods Provided by django-redis-cache
     :param key: Location of the value
     :rtype: bool
 
+.. function:: lock(self, key, timeout=None, sleep=0.1, blocking_timeout=None, thread_local=True)
 
-.. function:: expire(self, key, timeout):
-
-    Set the expire time on a key
-
-    :param key: Location of the value
-    :rtype: bool
+    See docs for `redis-py`_.
 
 
+.. _redis-py: https://redis-py.readthedocs.io/en/latest/_modules/redis/client.html#Redis.lock
diff --git a/docs/intro_quick_start.rst b/docs/intro_quick_start.rst
index f1b5384e..dd04b1cf 100644
--- a/docs/intro_quick_start.rst
+++ b/docs/intro_quick_start.rst
@@ -4,7 +4,7 @@ Intro and Quick Start
 Intro
 =====
 
-`django-redis-cache`_ is a cache backend for the `Django`_ webframework.  It
+`django-redis-cache`_ is a cache backend for the `Django`_ web framework.  It
 uses the `redis`_ server, which is a in-memory key-value data structure server.
 Similar to the great `Memcached`_ in performance, it has several features that
 makes it more appealing.
@@ -24,7 +24,7 @@ makes it more appealing.
     * Many more.
 
 Many of these features are irrelevant to caching, but can be used by other
-areas of a web stack and therefore offer a compelling case to simplify your
+areas of a web stack and therefore offers a compelling case to simplify your
 infrastructure.
 
 
@@ -35,9 +35,9 @@ Quick Start
 
 **Recommended:**
 
-* `redis`_ >= 2.4
+* `redis`_ >= 2.8
 
-* `redis-py`_ >= 2.10.3
+* `redis-py`_ >= 3.0.0
 
 * `python`_ >= 2.7
 
@@ -59,7 +59,7 @@ of redis.  Start the server by running ``./src/redis-server``
     }
 
 **Warning: By default, django-redis-cache set keys in the database 1 of Redis. By default, a session with redis-cli start on database 0. Switch to database 1 with** ``SELECT 1``.
-   
+
 .. _Django: https://www.djangoproject.com/
 .. _django-redis-cache: http://github.com/sebleier/django-redis-cache
 .. _redis-py: http://github.com/andymccurdy/redis-py/
diff --git a/redis_cache/backends/base.py b/redis_cache/backends/base.py
index 5ea3b53f..d473a635 100644
--- a/redis_cache/backends/base.py
+++ b/redis_cache/backends/base.py
@@ -1,3 +1,5 @@
+from functools import wraps
+
 from django.core.cache.backends.base import (
     BaseCache, DEFAULT_TIMEOUT, InvalidCacheBackendError,
 )
@@ -11,14 +13,9 @@
     )
 
 from redis.connection import DefaultParser
-
+from redis_cache.constants import KEY_EXPIRED, KEY_NON_VOLATILE
 from redis_cache.connection import pool
-from redis_cache.utils import (
-    CacheKey, get_servers, parse_connection_kwargs, import_class
-)
-
-
-from functools import wraps
+from redis_cache.utils import get_servers, parse_connection_kwargs, import_class
 
 
 def get_client(write=False):
@@ -28,8 +25,8 @@ def wrapper(method):
         @wraps(method)
         def wrapped(self, key, *args, **kwargs):
             version = kwargs.pop('version', None)
-            client = self.get_client(key, write=write)
             key = self.make_key(key, version=version)
+            client = self.get_client(key, write=write)
             return method(self, client, key, *args, **kwargs)
 
         return wrapped
@@ -76,6 +73,12 @@ def __init__(self, server, params):
             **self.compressor_class_kwargs
         )
 
+        redis_py_version = tuple(int(part) for part in redis.__version__.split('.'))
+        if redis_py_version < (3, 0, 0):
+            self.Redis = redis.StrictRedis
+        else:
+            self.Redis = redis.Redis
+
     def __getstate__(self):
         return {'params': self.params, 'server': self.server}
 
@@ -180,7 +183,7 @@ def create_client(self, server):
             socket_timeout=self.socket_timeout,
             socket_connect_timeout=self.socket_connect_timeout,
         )
-        client = redis.Redis(**kwargs)
+        client = self.Redis(**kwargs)
         kwargs.update(
             parser_class=self.parser_class,
             connection_pool_class=self.connection_pool_class,
@@ -216,12 +219,6 @@ def prep_value(self, value):
         value = self.serialize(value)
         return self.compress(value)
 
-    def make_key(self, key, version=None):
-        if not isinstance(key, CacheKey):
-            versioned_key = super(BaseRedisCache, self).make_key(key, version)
-            return CacheKey(key, versioned_key)
-        return key
-
     def make_keys(self, keys, version=None):
         return [self.make_key(key, version=version) for key in keys]
 
@@ -247,41 +244,34 @@ def add(self, client, key, value, timeout=DEFAULT_TIMEOUT):
         timeout = self.get_timeout(timeout)
         return self._set(client, key, self.prep_value(value), timeout, _add_only=True)
 
+    def _get(self, client, key, default=None):
+        value = client.get(key)
+        if value is None:
+            return default
+        value = self.get_value(value)
+        return value
+
     @get_client()
     def get(self, client, key, default=None):
         """Retrieve a value from the cache.
 
         Returns deserialized value if key is found, the default if not.
         """
-        value = client.get(key)
-        if value is None:
-            return default
-        value = self.get_value(value)
-        return value
+        return self._get(client, key, default)
 
     def _set(self, client, key, value, timeout, _add_only=False):
-        if timeout is None or timeout == 0:
-            if _add_only:
-                return client.setnx(key, value)
-            return client.set(key, value)
-        elif timeout > 0:
-            if _add_only:
-                added = client.setnx(key, value)
-                if added:
-                    client.expire(key, timeout)
-                return added
-            return client.setex(key, value, timeout)
-        else:
+        if timeout is not None and timeout < 0:
             return False
+        elif timeout == 0:
+            return client.expire(key, 0)
+        return client.set(key, value, nx=_add_only, ex=timeout)
 
     @get_client(write=True)
     def set(self, client, key, value, timeout=DEFAULT_TIMEOUT):
         """Persist a value to the cache, and set an optional expiration time.
         """
         timeout = self.get_timeout(timeout)
-
         result = self._set(client, key, self.prep_value(value), timeout, _add_only=False)
-
         return result
 
     @get_client(write=True)
@@ -328,12 +318,6 @@ def get_many(self, keys, version=None):
         """Retrieve many keys."""
         raise NotImplementedError
 
-    def _set_many(self, client, data):
-        # Only call mset if there actually is some data to save
-        if not data:
-            return True
-        return client.mset(data)
-
     def set_many(self, data, timeout=DEFAULT_TIMEOUT, version=None):
         """Set a bunch of values in the cache at once from a dict of key/value
         pairs. This is much more efficient than calling set() multiple times.
@@ -351,26 +335,27 @@ def incr(self, client, key, delta=1):
         exists = client.exists(key)
         if not exists:
             raise ValueError("Key '%s' not found" % key)
-        try:
-            value = client.incr(key, delta)
-        except redis.ResponseError:
-            key = key._original_key
-            value = self.get(key) + delta
-            self.set(key, value, timeout=None)
+
+        value = client.incr(key, delta)
+
         return value
 
-    def _incr_version(self, client, old, new, delta, version):
+    def _incr_version(self, client, old, new, original, delta, version):
         try:
             client.rename(old, new)
         except redis.ResponseError:
-            raise ValueError("Key '%s' not found" % old._original_key)
+            raise ValueError("Key '%s' not found" % original)
         return version + delta
 
     def incr_version(self, key, delta=1, version=None):
         """Adds delta to the cache version for the supplied key. Returns the
         new version.
         """
-        raise NotImplementedError
+
+    @get_client(write=True)
+    def touch(self, client, key, timeout=DEFAULT_TIMEOUT):
+        """Reset the timeout of a key to `timeout` seconds."""
+        return client.expire(key, timeout)
 
     #####################
     # Extra api methods #
@@ -388,9 +373,13 @@ def ttl(self, client, key):
         Otherwise, the value is the number of seconds remaining.  If the key
         does not exist, 0 is returned.
         """
-        if client.exists(key):
-            return client.ttl(key)
-        return 0
+        ttl = client.ttl(key)
+        if ttl == KEY_NON_VOLATILE:
+            return None
+        elif ttl == KEY_EXPIRED:
+            return 0
+        else:
+            return ttl
 
     def _delete_pattern(self, client, pattern):
         keys = list(client.scan_iter(match=pattern))
@@ -400,33 +389,78 @@ def _delete_pattern(self, client, pattern):
     def delete_pattern(self, pattern, version=None):
         raise NotImplementedError
 
+    def lock(
+            self,
+            key,
+            timeout=None,
+            sleep=0.1,
+            blocking_timeout=None,
+            thread_local=True):
+        client = self.get_client(key, write=True)
+        return client.lock(
+            key,
+            timeout=timeout,
+            sleep=sleep,
+            blocking_timeout=blocking_timeout,
+            thread_local=thread_local
+        )
+
     @get_client(write=True)
-    def get_or_set(self, client, key, func, timeout=DEFAULT_TIMEOUT):
+    def get_or_set(
+            self,
+            client,
+            key,
+            func,
+            timeout=DEFAULT_TIMEOUT,
+            lock_timeout=None,
+            stale_cache_timeout=None):
+        """Get a value from the cache or call ``func`` to set it and return it.
+
+        This implementation is slightly more advanced that Django's.  It provides thundering herd
+        protection, which prevents multiple threads/processes from calling the value-generating
+        function too much.
+
+        There are three timeouts you can specify:
+
+        ``timeout``: Time in seconds that value at ``key`` is considered fresh.
+        ``lock_timeout``: Time in seconds that the lock will stay active and prevent other threads or
+            processes from acquiring the lock.
+        ``stale_cache_timeout``: Time in seconds that the stale cache will remain after the key has
+            expired. If ``None`` is specified, the stale value will remain indefinitely.
+
+        """
         if not callable(func):
             raise Exception("Must pass in a callable")
 
-        value = self.get(key._original_key)
-
-        if value is None:
-
-            dogpile_lock_key = "_lock" + key._versioned_key
-            dogpile_lock = client.get(dogpile_lock_key)
+        lock_key = "__lock__" + key
+        fresh_key = "__fresh__" + key
 
-            if dogpile_lock is None:
-                # Set the dogpile lock.
-                self._set(client, dogpile_lock_key, 0, None)
+        is_fresh = self._get(client, fresh_key)
+        value = self._get(client, key)
 
-                # calculate value of `func`.
-                try:
-                    value = func()
-                finally:
-                    # Regardless of error, release the dogpile lock.
-                    client.expire(dogpile_lock_key, -1)
-
-                timeout = self.get_timeout(timeout)
+        if is_fresh:
+            return value
 
-                # Set value of `func` and set timeout
-                self._set(client, key, self.prep_value(value), timeout)
+        timeout = self.get_timeout(timeout)
+        lock = self.lock(lock_key, timeout=lock_timeout)
+
+        acquired = lock.acquire(blocking=False)
+
+        if acquired:
+            try:
+                value = func()
+            except Exception:
+                raise
+            else:
+                key_timeout = (
+                    None if stale_cache_timeout is None else timeout + stale_cache_timeout
+                )
+                pipeline = client.pipeline()
+                pipeline.set(key, self.prep_value(value), key_timeout)
+                pipeline.set(fresh_key, 1, timeout)
+                pipeline.execute()
+            finally:
+                lock.release()
 
         return value
 
@@ -453,12 +487,3 @@ def persist(self, client, key):
         Returns True if successful and False if not.
         """
         return client.persist(key)
-
-    @get_client(write=True)
-    def expire(self, client, key, timeout):
-        """
-        Set the expire time on a key
-
-        returns True if successful and False if not.
-        """
-        return client.expire(key, timeout)
diff --git a/redis_cache/backends/multiple.py b/redis_cache/backends/multiple.py
index 820dea98..d3d3f6c2 100644
--- a/redis_cache/backends/multiple.py
+++ b/redis_cache/backends/multiple.py
@@ -29,9 +29,8 @@ def shard(self, keys, write=False, version=None):
         """
         clients = defaultdict(list)
         for key in keys:
-            clients[self.get_client(key, write)].append(
-                self.make_key(key, version)
-            )
+            versioned_key = self.make_key(key, version=version)
+            clients[self.get_client(versioned_key, write)].append(versioned_key)
         return clients
 
     ####################
@@ -63,41 +62,28 @@ def get_many(self, keys, version=None):
         data = {}
         clients = self.shard(keys, version=version)
         for client, versioned_keys in clients.items():
-            original_keys = [key._original_key for key in versioned_keys]
+            versioned_keys = [self.make_key(key, version=version) for key in keys]
             data.update(
-                self._get_many(
-                    client,
-                    original_keys,
-                    versioned_keys=versioned_keys
-                )
+                self._get_many(client, keys, versioned_keys=versioned_keys)
             )
         return data
 
     def set_many(self, data, timeout=DEFAULT_TIMEOUT, version=None):
         """
-        Set a bunch of values in the cache at once from a dict of key/value
-        pairs. This is much more efficient than calling set() multiple times.
+        Set multiple values in the cache at once from a dict of key/value pairs.
 
         If timeout is given, that timeout will be used for the key; otherwise
         the default cache timeout will be used.
         """
         timeout = self.get_timeout(timeout)
+        versioned_key_to_key = {self.make_key(key, version=version): key for key in data.keys()}
+        clients = self.shard(versioned_key_to_key.values(), write=True, version=version)
 
-        clients = self.shard(data.keys(), write=True, version=version)
-
-        if timeout is None:
-            for client, keys in clients.items():
-                subset = {}
-                for key in keys:
-                    subset[key] = self.prep_value(data[key._original_key])
-                self._set_many(client, subset)
-            return
-
-        for client, keys in clients.items():
+        for client, versioned_keys in clients.items():
             pipeline = client.pipeline()
-            for key in keys:
-                value = self.prep_value(data[key._original_key])
-                self._set(pipeline, key, value, timeout)
+            for versioned_key in versioned_keys:
+                value = self.prep_value(data[versioned_key_to_key[versioned_key]])
+                self._set(pipeline, versioned_key, value, timeout)
             pipeline.execute()
 
     def incr_version(self, key, delta=1, version=None):
@@ -113,7 +99,7 @@ def incr_version(self, key, delta=1, version=None):
         old = self.make_key(key, version=version)
         new = self.make_key(key, version=version + delta)
 
-        return self._incr_version(client, old, new, delta, version)
+        return self._incr_version(client, old, new, key, delta, version)
 
     #####################
     # Extra api methods #
diff --git a/redis_cache/backends/single.py b/redis_cache/backends/single.py
index f13aec74..4a77ecf6 100644
--- a/redis_cache/backends/single.py
+++ b/redis_cache/backends/single.py
@@ -56,25 +56,18 @@ def get_many(self, keys, version=None):
 
     def set_many(self, data, timeout=DEFAULT_TIMEOUT, version=None):
         """
-        Set a bunch of values in the cache at once from a dict of key/value
-        pairs. This is much more efficient than calling set() multiple times.
+        Set multiple values in the cache at once from a dict of key/value pairs.
 
         If timeout is given, that timeout will be used for the key; otherwise
         the default cache timeout will be used.
         """
         timeout = self.get_timeout(timeout)
 
-        versioned_keys = self.make_keys(data.keys(), version=version)
-        if timeout is None:
-            new_data = {}
-            for key in versioned_keys:
-                new_data[key] = self.prep_value(data[key._original_key])
-            return self._set_many(self.master_client, new_data)
-
         pipeline = self.master_client.pipeline()
-        for key in versioned_keys:
-            value = self.prep_value(data[key._original_key])
-            self._set(pipeline, key, value, timeout)
+        for key, value in data.items():
+            value = self.prep_value(value)
+            versioned_key = self.make_key(key, version=version)
+            self._set(pipeline, versioned_key, value, timeout)
         pipeline.execute()
 
     def incr_version(self, key, delta=1, version=None):
@@ -89,7 +82,7 @@ def incr_version(self, key, delta=1, version=None):
         old = self.make_key(key, version)
         new = self.make_key(key, version=version + delta)
 
-        return self._incr_version(self.master_client, old, new, delta, version)
+        return self._incr_version(self.master_client, old, new, key, delta, version)
 
     #####################
     # Extra api methods #
diff --git a/redis_cache/constants.py b/redis_cache/constants.py
new file mode 100644
index 00000000..0c4e57b9
--- /dev/null
+++ b/redis_cache/constants.py
@@ -0,0 +1,2 @@
+KEY_EXPIRED = -2
+KEY_NON_VOLATILE = -1
diff --git a/redis_cache/utils.py b/redis_cache/utils.py
index a7ecd720..bc7dc859 100644
--- a/redis_cache/utils.py
+++ b/redis_cache/utils.py
@@ -6,30 +6,10 @@
 from django.utils.encoding import force_text, python_2_unicode_compatible
 from django.utils.six.moves.urllib.parse import parse_qs, urlparse
 
+from redis._compat import unicode
 from redis.connection import SSLConnection
 
 
-@python_2_unicode_compatible
-class CacheKey(object):
-    """
-    A stub string class that we can use to check if a key was created already.
-    """
-    def __init__(self, key, versioned_key):
-        self._original_key = key
-        self._versioned_key = versioned_key
-
-    def __eq__(self, other):
-        return self._versioned_key == other
-
-    def __str__(self):
-        return force_text(self._versioned_key)
-
-    def __hash__(self):
-        return hash(self._versioned_key)
-
-    __repr__ = __str__
-
-
 def get_servers(location):
     """Returns a list of servers given the server argument passed in from
     Django.
diff --git a/requirements-dev.txt b/requirements-dev.txt
index a910d2be..e13ff66c 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -2,4 +2,4 @@ hiredis==0.2.0
 django-nose==1.4.4
 nose==1.3.6
 msgpack-python==0.4.6
-pyyaml==3.11
+pyyaml>=4.2b1
diff --git a/requirements.txt b/requirements.txt
index 91015469..fb8f42f8 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1 @@
-redis==2.10.6
+redis<4.0
diff --git a/setup.py b/setup.py
index 7373ddf6..ab9b64d3 100644
--- a/setup.py
+++ b/setup.py
@@ -5,11 +5,11 @@
     url="http://github.com/sebleier/django-redis-cache/",
     author="Sean Bleier",
     author_email="sebleier@gmail.com",
-    version="1.8.1",
+    version="2.0.0",
     license="BSD",
     packages=["redis_cache", "redis_cache.backends"],
     description="Redis Cache Backend for Django",
-    install_requires=['redis==2.10.6'],
+    install_requires=['redis<4.0'],
     classifiers=[
         "Programming Language :: Python",
         "Programming Language :: Python :: 2.7",
diff --git a/tests/testapp/tests/base_tests.py b/tests/testapp/tests/base_tests.py
index 4af2f3ed..719ec779 100644
--- a/tests/testapp/tests/base_tests.py
+++ b/tests/testapp/tests/base_tests.py
@@ -4,6 +4,7 @@
 from hashlib import sha1
 import os
 import subprocess
+import threading
 import time
 
 
@@ -21,6 +22,7 @@
 
 from tests.testapp.models import Poll, expensive_calculation
 from redis_cache.cache import RedisCache, pool
+from redis_cache.constants import KEY_EXPIRED, KEY_NON_VOLATILE
 from redis_cache.utils import get_servers, parse_connection_kwargs
 
 
@@ -299,13 +301,12 @@ def test_set_expiration_timeout_None(self):
     def test_set_expiration_timeout_zero(self):
         key, value = self.cache.make_key('key'), 'value'
         self.cache.set(key, value, timeout=0)
-        self.assertIsNone(self.cache.get_client(key).ttl(key))
-        self.assertIn(key, self.cache)
+        self.assertEqual(self.cache.get_client(key).ttl(key), KEY_EXPIRED)
+        self.assertNotIn(key, self.cache)
 
     def test_set_expiration_timeout_negative(self):
         key, value = self.cache.make_key('key'), 'value'
         self.cache.set(key, value, timeout=-1)
-        self.assertIsNone(self.cache.get_client(key).ttl(key))
         self.assertNotIn(key, self.cache)
 
     def test_unicode(self):
@@ -481,9 +482,9 @@ def test_ttl_of_reinsert_keys(self):
         self.cache.set('b', 'b', 5)
         self.cache.reinsert_keys()
         self.assertEqual(self.cache.get('a'), 'a')
-        self.assertGreater(self.cache.get_client('a').ttl(self.cache.make_key('a')), 1)
+        self.assertGreater(self.cache.ttl('a'), 1)
         self.assertEqual(self.cache.get('b'), 'b')
-        self.assertGreater(self.cache.get_client('b').ttl(self.cache.make_key('b')), 1)
+        self.assertGreater(self.cache.ttl('a'), 1)
 
     def test_get_or_set(self):
 
@@ -510,6 +511,66 @@ def expensive_function():
         self.assertEqual(expensive_function.num_calls, 2)
         self.assertEqual(value, 42)
 
+    def test_get_or_set_serving_from_stale_value(self):
+
+        def expensive_function(x):
+            time.sleep(.5)
+            expensive_function.num_calls += 1
+            return x
+
+        expensive_function.num_calls = 0
+        self.assertEqual(expensive_function.num_calls, 0)
+        results = {}
+
+        def thread_worker(thread_id, return_value, timeout, lock_timeout, stale_cache_timeout):
+            value = self.cache.get_or_set(
+                'key',
+                lambda: expensive_function(return_value),
+                timeout,
+                lock_timeout,
+                stale_cache_timeout
+            )
+            results[thread_id] = value
+
+        thread_0 = threading.Thread(target=thread_worker, args=(0, 'a', 1, None, 1))
+        thread_1 = threading.Thread(target=thread_worker, args=(1, 'b', 1, None, 1))
+        thread_2 = threading.Thread(target=thread_worker, args=(2, 'c', 1, None, 1))
+        thread_3 = threading.Thread(target=thread_worker, args=(3, 'd', 1, None, 1))
+        thread_4 = threading.Thread(target=thread_worker, args=(4, 'e', 1, None, 1))
+
+        # First thread should complete and return its value
+        thread_0.start()  # t = 0, valid from t = .5 - 1.5, stale from t = 1.5 - 2.5
+
+        # Second thread will start while the first thread is still working and return None.
+        time.sleep(.25)  # t = .25
+        thread_1.start()
+        # Third thread will start after the first value is computed, but before it expires.
+        # its value.
+        time.sleep(.5)  # t = .75
+        thread_2.start()
+        # Fourth thread will start after the first value has expired and will re-compute its value.
+        # valid from t = 2.25 - 3.25, stale from t = 3.75 - 4.75.
+        time.sleep(1)  # t = 1.75
+        thread_3.start()
+        # Fifth thread will start after the fourth thread has started to compute its value, but
+        # before the first thread's stale cache has expired.
+        time.sleep(.25)  # t = 2
+        thread_4.start()
+
+        thread_0.join()
+        thread_1.join()
+        thread_2.join()
+        thread_3.join()
+        thread_4.join()
+
+        self.assertEqual(results, {
+            0: 'a',
+            1: None,
+            2: 'a',
+            3: 'd',
+            4: 'a'
+        })
+
     def assertMaxConnection(self, cache, max_num):
         for client in cache.clients.values():
             self.assertLessEqual(client.connection_pool._created_connections, max_num)
@@ -581,21 +642,21 @@ def test_persist_expire_to_persist(self):
         self.cache.persist('a')
         self.assertIsNone(self.cache.ttl('a'))
 
-    def test_expire_no_expiry_to_expire(self):
+    def test_touch_no_expiry_to_expire(self):
         self.cache.set('a', 'a', timeout=None)
-        self.cache.expire('a', 10)
+        self.cache.touch('a', 10)
         ttl = self.cache.ttl('a')
         self.assertAlmostEqual(ttl, 10)
 
-    def test_expire_less(self):
+    def test_touch_less(self):
         self.cache.set('a', 'a', timeout=20)
-        self.cache.expire('a', 10)
+        self.cache.touch('a', 10)
         ttl = self.cache.ttl('a')
         self.assertAlmostEqual(ttl, 10)
 
-    def test_expire_more(self):
+    def test_touch_more(self):
         self.cache.set('a', 'a', timeout=10)
-        self.cache.expire('a', 20)
+        self.cache.touch('a', 20)
         ttl = self.cache.ttl('a')
         self.assertAlmostEqual(ttl, 20)