Hi,
I just added a comment on a GitHub issue:
as I am experiencing a similar behavior, memory is not released even when the session is discarded.
I am posting the issue here as well as the problem may be different, probably on wrong usage of the on_session_destroyed() method.
It looks a bit hackish, but I tried to reduce the code a MRE, attached below:
import hvplot.xarray
import xarray as xr
import panel as pn
import holoviews as hv
import sys
from bokeh.layouts import column, Spacer
import gc
pn.param.ParamMethod.loading_indicator = True
ds = None
def on_server_loaded():
print("server loaded")
print("")
sys.stdout.flush()
def on_session_created(session_context):
print("session created")
print("")
sys.stdout.flush()
def on_session_destroyed(session_context):
print("session destroyed")
print("")
print(dir(session_context))
try:
del ds
gc.collect()
except UnboundLocalError:
pass
try:
del plot_widget
gc.collect()
except UnboundLocalError:
pass
plot_widget = None
gc.collect()
sys.stdout.flush()
def load_data(url):
try:
del ds
gc.collect()
except UnboundLocalError:
pass
ds = None
try:
# attempt to load the dataset via xarray with decode_times=True
ds = xr.open_dataset(str(url).strip())
except ValueError as e:
# attempt to load the dataset via xarray with decode_times=False
ds = xr.open_dataset(str(url).strip(), decode_times=False)
print(e)
except OSError as e:
print(e)
if ds and not ds.coords:
del ds
gc.collect()
# the following hack is used when the dataset is served as a tabledap via erdap
erdapp_uglyness = list(dict(xr.open_dataset(url).dims).keys())[0]
renamed_vars = {i:i.replace(erdapp_uglyness+".", "") for i in list(xr.open_dataset(url).variables.keys())}
new_nc_url = url+'?'+'time,'+','.join(list(xr.open_dataset(url).variables)).replace(f"{erdapp_uglyness}.", "").replace(f"time,", "")
ds = xr.open_dataset(new_nc_url)
ds = ds.set_coords(f"{erdapp_uglyness}.time")
ds = ds.swap_dims(s=f"time")
ds = ds.set_xindex(f"{erdapp_uglyness}.time")
ds = ds.rename_vars(renamed_vars)
return ds
def plot(var, title=None):
try:
del plot_widget
gc.collect()
except UnboundLocalError:
pass
plot_widget = None
try:
del ds
gc.collect()
except UnboundLocalError:
pass
gc.collect()
ds = load_data(url)
var = var[0]
print(f'plotting var: {var}')
if not title:
try:
title = f"{ds[var].attrs['long_name']}"
except KeyError:
title = f"{var}"
else:
title=title
if 'featureType' in ds.attrs:
featureType = ds.attrs['featureType'].lower()
elif 'cdm_data_type' in ds[var].attrs:
featureType = ds[var].attrs['cdm_data_type'].lower()
else:
featureType = None
is_monotonic = False
if featureType == 'timeseries':
axis_arguments = {'grid':True, 'title': title, 'responsive': True}
plot_widget = ds[var].where(ds[var] != 9.96921e36).hvplot.line(**axis_arguments)
return plot_widget
if featureType != "timeseries":
axis_arguments = {'x': ds[var], 'grid':True, 'title': title, 'widget_location': 'bottom', 'responsive': True}
try:
plot_widget = ds[var].where(ds[var] != 9.96921e36).hvplot.line(**axis_arguments)
except TypeError:
axis_arguments = {'grid':True, 'title': title, 'widget_location': 'bottom', 'responsive': True}
plot_widget = ds[var].where(ds[var] != 9.96921e36).hvplot.line(**axis_arguments)
except ValueError:
axis_arguments = {'x': var, 'grid':True, 'title': title, 'widget_location': 'bottom', 'responsive': True}
plot_widget = ds[var].where(ds[var] != 9.96921e36).hvplot.line(**axis_arguments)
return plot_widget
def on_var_select(event):
var = event.obj.value
result = [key for key, value in mapping_var_names.items() if value == var]
with pn.param.set_values(main_app, loading=True):
plot_container[-1] = plot(var=result, title=var)
print(f'selected {result}')
def safe_check(var):
try:
ds[var].values
return var
except Exception as e:
# Handle the exception (e.g., log it, return False, etc.)
print(f"Error processing {var}: {e}")
return False
pn.state.onload(callback=on_server_loaded)
# pn.state.on_session_created(callback=on_session_created)
pn.state.on_session_destroyed(callback=on_session_destroyed)
url = pn.state.session_args.get('url')[0].decode("utf8")
print("++++++++++++++++++++++++ LOADING ++++++++++++++++++++++++++++++++++++")
print(str(url))
print("++++++++++++++++++++++++ +++++++ ++++++++++++++++++++++++++++++++++++")
ds = load_data(url)
if ds:
plottable_vars = [j for j in ds if len([value for value in list(ds[j].coords) if value in list(ds.dims)]) >= 1]
plottable_vars = [i for i in plottable_vars if safe_check(i)]
print("plottable_vars:", plottable_vars )
mapping_var_names = {}
for i in plottable_vars:
if int(len(list(ds[i].coords)) != 0):
try:
title = f"{ds[i].attrs['long_name']} [{i}]"
except KeyError:
title = f"{i}"
mapping_var_names[i] = title
# add a select widget for variables, uses long names
variables_selector = pn.widgets.Select(options=list(mapping_var_names.values()), name='Data Variable')
variables_selector.param.watch(on_var_select, parameter_names=['value'])
selected_var = [key for key, value in mapping_var_names.items() if value == variables_selector.value]
plot_plot = plot(selected_var, title=variables_selector.value)
plot_container = pn.Column(pn.Row(variables_selector), plot_plot, sizing_mode='scale_both') # , sizing_mode='scale_both'
main_app = pn.Row(plot_container, Spacer(width=10))
main_app.servable()
Thank you so much for any help!