Debugging a max output bytes issue

[paddymul]

I have a widget, buckaroo which displays dataframes as modern tables. On smaller dataframes it works fine, as dataframes grow I eventually get to a MAX_OUTPUT_BYTES error.

This is surprising, because my widget is setup to poll the server for the displayed ranges of the dataframe. I wrote a debugging function to see which traits are taking up the majority of space. I still haven't found the culprit. I thought I'd share here for ideas, or to help someone else running into the same problem.

import json
def size_debug_widget(widget):
    running_sum = 0
    for k, v in widget.traits().items():
        if v.metadata.get('sync'):
            actual_val = getattr(widget, k)
            l = 0

            try: 
                l = len(json.dumps(actual_val))
            except:
                print(k, "error")
                pass
            running_sum += l
            print(k, l)
    print("total", running_sum)

None of the traits grow significantly with larger dataframes. So this is all a bit surprising.

Currently my app sets widget traits based on the displayed range. Either way, the entire dataframe should never be sent to the browser, so I'm ata. loss for why the MAX_OUTPUT_BYTES limit is reached. the json encoded sum of all of my traits is 4_431_142

I'm working on an improved version which uses comm messages to communicate the data. I hope that will fix the problem.

If there is anything obvious that I'm overlooking, I'm all ears.

[paddymul]

Filed a bug with a reproduction against anywidget
manzt/anywidget#809