perf: memory consumption for the stock balance report (#39626)

(cherry picked from commit b70f3de)

erpnext/stock/report/stock_balance/stock_balance.py

@@ -90,16 +90,16 @@ def prepare_opening_data_from_closing_balance(self) -> None:
 				self.opening_data.setdefault(group_by_key, entry)
 
 	def prepare_new_data(self):
-		if not self.sle_entries:
-			return
+		self.item_warehouse_map = self.get_item_warehouse_map()
 
 		if self.filters.get("show_stock_ageing_data"):
 			self.filters["show_warehouse_wise_stock"] = True
 			item_wise_fifo_queue = FIFOSlots(self.filters, self.sle_entries).generate()
 
 		_func = itemgetter(1)
 
-		self.item_warehouse_map = self.get_item_warehouse_map()
+		del self.sle_entries
+
 		sre_details = self.get_sre_reserved_qty_details()
 
 		variant_values = {}
@@ -143,15 +143,22 @@ def get_item_warehouse_map(self):
 		item_warehouse_map = {}
 		self.opening_vouchers = self.get_opening_vouchers()
 
-		for entry in self.sle_entries:
-			group_by_key = self.get_group_by_key(entry)
-			if group_by_key not in item_warehouse_map:
-				self.initialize_data(item_warehouse_map, group_by_key, entry)
+		if self.filters.get("show_stock_ageing_data"):
+			self.sle_entries = self.sle_query.run(as_dict=True)
+
+		with frappe.db.unbuffered_cursor():
+			if not self.filters.get("show_stock_ageing_data"):
+				self.sle_entries = self.sle_query.run(as_dict=True, as_iterator=True)
+
+			for entry in self.sle_entries:
+				group_by_key = self.get_group_by_key(entry)
+				if group_by_key not in item_warehouse_map:
+					self.initialize_data(item_warehouse_map, group_by_key, entry)
 
-			self.prepare_item_warehouse_map(item_warehouse_map, entry, group_by_key)
+				self.prepare_item_warehouse_map(item_warehouse_map, entry, group_by_key)
 
-			if self.opening_data.get(group_by_key):
-				del self.opening_data[group_by_key]
+				if self.opening_data.get(group_by_key):
+					del self.opening_data[group_by_key]
 
 		for group_by_key, entry in self.opening_data.items():
 			if group_by_key not in item_warehouse_map:
@@ -252,7 +259,8 @@ def get_closing_balance(self) -> List[Dict[str, Any]]:
 			.where(
 				(table.docstatus == 1)
 				& (table.company == self.filters.company)
-				& ((table.to_date <= self.from_date))
+				& (table.to_date <= self.from_date)
+				& (table.status == "Completed")
 			)
 			.orderby(table.to_date, order=Order.desc)
 			.limit(1)
@@ -305,7 +313,7 @@ def prepare_stock_ledger_entries(self):
 		if self.filters.get("company"):
 			query = query.where(sle.company == self.filters.get("company"))
 
-		self.sle_entries = query.run(as_dict=True)
+		self.sle_query = query
 
 	def apply_inventory_dimensions_filters(self, query, sle) -> str:
 		inventory_dimension_fields = self.get_inventory_dimension_fields()