Send pending data after each block

src/filter.py

@@ -359,6 +359,9 @@ class Filter(object):
                     processed = function(array, interval, args,
                                          insert_function, False)
 
+                    # Send any pending data
+                    insert_ctx.send()
+
                     # Save the unprocessed parts
                     if processed > 0:
                         old_array = array[processed:]