Stream callback invoked twice in FastGridTemplate

[yt87]

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ALL software version info

panel                     1.4.2              pyhd8ed1ab_0    conda-forge
holoviews                 1.18.3             pyhd8ed1ab_0    conda-forge
hvplot                    0.9.2              pyhd8ed1ab_0    conda-forge
panel                     1.4.2              pyhd8ed1ab_0    conda-forge
xarray                    2024.3.0           pyhd8ed1ab_0    conda-forge

Description of expected behavior and the observed behavior

The code below runs as expected. When I replace FastListTemplate by FastGridTemplate, the function image is invoked twice per each tap. The output for 2 random taps looks like this:

FastListTemplate

=====1 212.17401500938087 40.78488372093024 Sun May  5 01:02:34 2024
=====2 212.17401500938087 40.78488372093024 Sun May  5 01:02:36 2024
=====1 225.90370018975332 30.416666666666664 Sun May  5 01:02:38 2024
=====2 225.90370018975332 30.416666666666664 Sun May  5 01:02:40 2024

FastGridTemplate

=====1 215.59535104364326 36.36904761904762 Sun May  5 01:01:48 2024
=====2 215.59535104364326 36.36904761904762 Sun May  5 01:01:50 2024
=====1 215.59535104364326 36.36904761904762 Sun May  5 01:01:51 2024
=====2 215.59535104364326 36.36904761904762 Sun May  5 01:01:53 2024
=====1 259.3429791271347 68.21428571428571 Sun May  5 01:01:58 2024
=====2 259.3429791271347 68.21428571428571 Sun May  5 01:02:00 2024
=====1 259.3429791271347 68.21428571428571 Sun May  5 01:02:00 2024
=====2 259.3429791271347 68.21428571428571 Sun May  5 01:02:02 2024

Complete, minimal, self-contained example code that reproduces the issue

# code goes here between backticks
import time

import panel as pn
import xarray as xr
import holoviews as hv
import hvplot.xarray

pn.extension()

ds = xr.tutorial.open_dataset('air_temperature')
_image = ds.hvplot('lon', 'lat')
stream = hv.streams.Tap(source=_image, x=-88 + 360, y=40)

def image(x, y):
    print('=====1', x, y, time.ctime())
    time.sleep(2)
    print('=====2', x, y, time.ctime())
    return _image * hv.Points([(x, y)], label='x: %0.3f, y: %0.3f' % (x, y)).opts(color='red', size=10)


item = pn.bind(image, stream.param.x, stream.param.y)
layout = pn.template.FastListTemplate(title='FastList', main=[item])
#layout = pn.template.FastGridTemplate(title='FastGrid')
#layout.main[0:6, 0:6] = item
layout.servable()

Stack traceback and/or browser JavaScript console output

Screenshots or screencasts of the bug in action

• I may be interested in making a pull request to address this