Colabtools: Dask client not running on Colab

[cornhundred]

Dask client is not running on Colab. My code is:

from dask.distributed import Client, progress
client = Client()
client

and the error is:

/usr/local/lib/python3.6/dist-packages/distributed/bokeh/core.py:57: UserWarning: 
Port 8787 is already in use. 
Perhaps you already have a cluster running?
Hosting the diagnostics dashboard on a random port instead.
  warnings.warn('\n' + msg)
tornado.application - ERROR - Multiple exceptions in yield list
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/dist-packages/tornado/gen.py", line 828, in callback
    result_list.append(f.result())
  File "/usr/local/lib/python3.6/dist-packages/tornado/concurrent.py", line 238, in result
    raise_exc_info(self._exc_info)
  File "<string>", line 4, in raise_exc_info
  File "/usr/local/lib/python3.6/dist-packages/tornado/gen.py", line 1069, in run
    yielded = self.gen.send(value)
  File "/usr/local/lib/python3.6/dist-packages/distributed/deploy/local.py", line 229, in _start_worker
    raise gen.TimeoutError("Worker failed to start")
tornado.gen.TimeoutError: Worker failed to start
---------------------------------------------------------------------------
TimeoutError                              Traceback (most recent call last)
/usr/local/lib/python3.6/dist-packages/tornado/gen.py in callback(f)
    827                 try:
--> 828                     result_list.append(f.result())
    829                 except Exception as e:

33 frames
TimeoutError: Worker failed to start

During handling of the above exception, another exception occurred:

TimeoutError                              Traceback (most recent call last)
/usr/local/lib/python3.6/dist-packages/distributed/deploy/local.py in _start_worker(self, death_timeout, **kwargs)
    227         if w.status == 'closed' and self.scheduler.status == 'running':
    228             self.workers.remove(w)
--> 229             raise gen.TimeoutError("Worker failed to start")
    230 
    231         raise gen.Return(w)

TimeoutError: Worker failed to start

To reproduce the error please see the following Colab gist:

https://colab.research.google.com/gist/cornhundred/70524e9425db14f3adec9e86660aa313/trying_dask_on_colab.ipynb

The issue was also raised here https://github.com/dask/dask/issues/4843 with Dask

[randerzander]

@cornhundred I was able to create a Dask LocalCluster in Colab this way:

from dask.distributed import Client, LocalCluster

cluster = LocalCluster(processes=False)
client = Client(cluster)
client

[blois]

Just a note that the Dask dashboard does not work natively in Colab because websocket connections are not supported between the client and the kernel.

from dask.distributed import Client, progress
client = Client(processes=False)
client

[odovad]

Seems that it does not work anymore.

from dask.distributed import Client
client = Client(processes=False)
client

I have to modify with Client(processes=False, diagnostic_port=None)

It would be great to be able to access the diagnostic dashboard or to be able to see everything inside the notebook (with Progress).

Someone has a solution because everything runs well but with no supervision.