Fix memory leak during successful CSV rendering

- Delay return until Context Manager `with open()` has finished and force GC in between. - Explicitly `del` data, reader, sheets when they are on longer used.

Author: cslzchen

mfr/extensions/tabular/libs/stdlib_tools.py

@@ -20,6 +20,7 @@ def csv_stdlib(fp):
  else:
  _set_dialect_quote_attrs(dialect, data)
 
+ del data
  reader = csv.DictReader(fp, dialect=dialect)
  columns = []
  # update the reader field names to avoid duplicate column names when performing row extraction
@@ -53,6 +54,7 @@ def csv_stdlib(fp):
  if not columns and not rows:
  raise EmptyTableError('Table empty or corrupt.', extension='csv')
 
+ del reader
  return {'Sheet 1': (columns, rows)}
 
 

mfr/extensions/tabular/render.py

@@ -32,16 +32,20 @@ def render(self):
 
  with open(self.file_path, errors='replace') as fp:
  sheets, size, nbr_rows, nbr_cols = self._render_grid(fp, self.metadata.ext)
- # gc.collect()
- if sheets and size:
- return self.TEMPLATE.render(
- base=self.assets_url,
- width=settings.TABLE_WIDTH,
- height=settings.TABLE_HEIGHT,
- sheets=json.dumps(sheets),
- options=json.dumps(size),
+
+ # Force GC
+ gc.collect()
+
+ if sheets and size:
+ return self.TEMPLATE.render(
+ base=self.assets_url,
+ width=settings.TABLE_WIDTH,
+ height=settings.TABLE_HEIGHT,
+ sheets=json.dumps(sheets),
+ options=json.dumps(size),
  )
- # gc.collect()
+
+ assert nbr_rows and nbr_cols
  raise exceptions.TableTooBigError(
  'Table is too large to render.',
  extension=self.metadata.ext,
@@ -93,6 +97,7 @@ def _render_grid(self, fp, ext, *args, **kwargs):
  break
 
  if table_too_big:
+ del sheets
  return None, None, nbr_rows, nbr_cols
 
  return sheets, size, None, None