What happened:

When creating a LocalCluster object the comm is started on a random high port, even if there are no other clusters running.

What you expected to happen:

Should use port 8786.

Minimal Complete Verifiable Example:

$ conda create -n dask-lc-test -c conda-forge -y python=3.8 ipython dask distributed
$ conda activate dask-lc-test

The dask-scheduler command works as expeted.

$ dask-scheduler
distributed.scheduler - INFO - -----------------------------------------------
distributed.scheduler - INFO - -----------------------------------------------
distributed.scheduler - INFO - Clear task state
distributed.scheduler - INFO -   Scheduler at:   tcp://10.51.100.43:8786
distributed.scheduler - INFO -   dashboard at:                     :8787

But LocalCluster does not.

>>> from dask.distributed import LocalCluster
>>> cluster = LocalCluster()
>>> cluster.scheduler_address
'tcp://127.0.0.1:45083'

Anything else we need to know?:

• Dask version: 2020.12.0 (tried latest source too)
• Python version: 3.8
• Operating System: macOS and Ubuntu 18.04
• Install method (conda, pip, source): conda and source