alt.Chart.from_json slow after upgrading jsonschema from 3.x to 4.x

[the21st]

I tested all of the below with altair version 4.1.0.

I recently upgraded my jupyter stack to the following versions:
notebook==6.4.4
ipython==7.28.0
ipykernel==6.4.1

Update: The culprit downstream dependency is jsonschema==4.1.0

Since then, alt.Chart.from_json(spec) takes 2.6 seconds on my machine. Code to reproduce:

import time
import altair as alt

spec = """
{
  "$schema": "https://vega.github.io/schema/vega-lite/v4.json",
  "mark": {
    "type": "bar",
    "tooltip": {
      "content": "data"
    }
  },
  "height": 220,
  "autosize": {
    "type": "fit"
  },
  "data": {
    "name": "placeholder"
  },
  "encoding": {
    "x": {
      "field": "bookID",
      "type": "quantitative",
      "sort": null,
      "scale": {
        "type": "linear",
        "zero": false
      }
    },
    "y": {
      "field": "title",
      "type": "nominal",
      "sort": null,
      "scale": {
        "type": "linear",
        "zero": true
      }
    },
    "color": {
      "field": "",
      "type": "nominal",
      "sort": null,
      "scale": {
        "type": "linear",
        "zero": false
      }
    }
  }
}
"""

start = time.time()
chart = alt.Chart.from_json(spec)
end = time.time()
print(end - start)

Running the same code on an older version jsonschema==3.2.0 executes in 0.03 seconds.

Note that I am not yet passing any data to altair, just a data-less vega-lite spec.

[jakevdp]

Thanks for the report: this seems to be due to python-jsonschema/jsonschema#853

For now, I'd suggest using jsonschema version 3.2 with Altair.

[joelostblom]

closing as there is nothing to do on the altair side of things and there are newer versions of jsonschema to use