dask computation not executing in parallel
<p>I have a directory of json files that I am trying to convert to a dask DataFrame and save it to castra.
There are 200 files containing O(10**7) json records between them.
The code is very simple largely following tutorial examples.</p>

<pre><code>import dask.dataframe as dd
import dask.bag as db
import json
txt = db.from_filenames('part-*.json')
js = txt.map(json.loads)
df = js.to_dataframe()
cs=df.to_castra("data.castra")
</code></pre>

<p>I am running it on a 32 core machine, but the code only utilizes one core at 100%.
My understanding from the docs is that this code execute in parallel.
Why is it not?
Did I misunderstand something?</p>