AttributeError: module 'msgpack' has no attribute 'dumps'

[free-soellingeraj]

ray.version = '0.8.7'

# This function is a proxy for a more interesting and computationally
# intensive function.
@ray.remote
def slow_function(i):
    time.sleep(1)
    return i

# Sleep a little to improve the accuracy of the timing measurements below.
# We do this because workers may still be starting up in the background.
time.sleep(2.0)
start_time = time.time()

results = [slow_function.remote(i) for i in range(4)]

end_time = time.time()
duration = end_time - start_time

print('The results are {}. This took {} seconds. Run the next cell to see '
      'if the exercise was done correctly.'.format(results, duration))

yields error:

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-12-642b7e800d47> in <module>
      4 start_time = time.time()
      5 
----> 6 results = [slow_function.remote(i) for i in range(4)]
      7 
      8 end_time = time.time()

<ipython-input-12-642b7e800d47> in <listcomp>(.0)
      4 start_time = time.time()
      5 
----> 6 results = [slow_function.remote(i) for i in range(4)]
      7 
      8 end_time = time.time()

/opt/conda/lib/python3.6/site-packages/ray/remote_function.py in _remote_proxy(*args, **kwargs)
     93         @wraps(function)
     94         def _remote_proxy(*args, **kwargs):
---> 95             return self._remote(args=args, kwargs=kwargs)
     96 
     97         self.remote = _remote_proxy

/opt/conda/lib/python3.6/site-packages/ray/remote_function.py in _remote(self, args, kwargs, num_return_vals, is_direct_call, num_cpus, num_gpus, memory, object_store_memory, resources, max_retries)
    216             invocation = self._decorator(invocation)
    217 
--> 218         return invocation(args, kwargs)

/opt/conda/lib/python3.6/site-packages/ray/remote_function.py in invocation(args, kwargs)
    206             object_refs = worker.core_worker.submit_task(
    207                 self._language, self._function_descriptor, list_args,
--> 208                 num_return_vals, resources, max_retries)
    209 
    210             if len(object_refs) == 1:

python/ray/_raylet.pyx in ray._raylet.CoreWorker.submit_task()

python/ray/_raylet.pyx in ray._raylet.CoreWorker.submit_task()

python/ray/_raylet.pyx in ray._raylet.prepare_args()

/opt/conda/lib/python3.6/site-packages/ray/serialization.py in serialize(self, value)
    390                 metadata = ray_constants.OBJECT_METADATA_TYPE_PYTHON
    391 
--> 392             return self._serialize_to_msgpack(metadata, value)
    393 
    394     def register_custom_serializer(self,

/opt/conda/lib/python3.6/site-packages/ray/serialization.py in _serialize_to_msgpack(self, metadata, value)
    358             return index
    359 
--> 360         msgpack_data = MessagePackSerializer.dumps(value, _python_serializer)
    361 
    362         if python_objects:

python/ray/includes/serialization.pxi in ray._raylet.MessagePackSerializer.dumps()

AttributeError: module 'msgpack' has no attribute 'dumps'

[free-soellingeraj]

I am not familiar with _raylet.so format enough to understand what this means. I am going to try to eliminate some possibilities by rebuilding a purpose driven version of my training env for RL with ray