Plot.cleanup() severs other plots' subscribers on shared streams: owner filter defeated by _WeakSubscriber.__bool__

[SimonHeybrock]

Description

DimensionedPlot.cleanup is documented and written to remove only the stream subscribers owned by the plot being cleaned (get_method_owner(subscriber) not in plots). Since subscribers became _WeakSubscriber wrappers (the weak-subscriber work around #6875), that owner filter is dead code: the wrapper's __bool__ returns False for any param-method subscriber — which every plot-refresh subscriber is — so the leading subscriber and (...) in the filter short-circuits and cleanup removes every weakly-wrapped plot-refresh subscriber on the touched streams, including those of other live plots. A surviving view of the same object silently stops updating.

Complete, minimal, self-contained example

import holoviews as hv
hv.extension('bokeh')

pipe = hv.streams.Pipe(data=[1, 2, 3])
dmap = hv.DynamicMap(lambda data: hv.Curve(data), streams=[pipe])
r = hv.renderer('bokeh')
plot1 = r.get_plot(dmap)
plot2 = r.get_plot(dmap)
print(len(pipe.subscribers))  # 2

plot1.cleanup()
print(len(pipe.subscribers))  # 0  <- plot2's subscriber removed as well

pipe.send([8, 9])
print(len(plot2.current_frame.dimension_values(0)))  # unchanged: plot2 is dead

Versions: holoviews 1.23.1 (behavior unchanged on current main), bokeh 3.9.2, Python 3.12.

If treating weak param-method subscribers as always-reapable is intentional, the docstring and owner filter are misleading and the sharing hazard above deserves a note; if not, _WeakSubscriber could expose its referent so the owner check works again. Can submit a PR once maintainers indicate which reading is intended.

Context: hit while working around holoviz/panel#8710, where explicit plot.cleanup() is the app-side fix (scipp/esslivedata#1224) — its correctness currently relies on cleaning up before the surviving plot renders.