[Python-Dev] Possible performance regression

[Raymond Hettinger]

I'll been running benchmarks that have been stable for a while.  But between today and yesterday, there has been an almost across the board performance regression.  

It's possible that this is a measurement error or something unique to my system (my Mac installed the 10.14.3 release today), so I'm hoping other folks can run checks as well.


Raymond


-- Yesterday ------------------------------------------------------------------------

$ ./python.exe Tools/scripts/var_access_benchmark.py
Variable and attribute read access:
   4.0 ns	read_local
   4.5 ns	read_nonlocal
  13.1 ns	read_global
  17.4 ns	read_builtin
  17.4 ns	read_classvar_from_class
  15.8 ns	read_classvar_from_instance
  24.6 ns	read_instancevar
  19.7 ns	read_instancevar_slots
  18.5 ns	read_namedtuple
  26.3 ns	read_boundmethod

Variable and attribute write access:
   4.6 ns	write_local
   4.8 ns	write_nonlocal
  17.5 ns	write_global
  39.1 ns	write_classvar
  34.4 ns	write_instancevar
  25.3 ns	write_instancevar_slots

Data structure read access:
  17.5 ns	read_list
  18.4 ns	read_deque
  19.2 ns	read_dict

Data structure write access:
  19.0 ns	write_list
  22.0 ns	write_deque
  24.4 ns	write_dict

Stack (or queue) operations:
  55.5 ns	list_append_pop
  46.3 ns	deque_append_pop
  46.7 ns	deque_append_popleft

Timing loop overhead:
   0.3 ns	loop_overhead


-- Today ---------------------------------------------------------------------------

$ ./python.exe py Tools/scripts/var_access_benchmark.py

Variable and attribute read access:
   5.0 ns	read_local
   5.3 ns	read_nonlocal
  14.7 ns	read_global
  18.6 ns	read_builtin
  19.9 ns	read_classvar_from_class
  17.7 ns	read_classvar_from_instance
  26.1 ns	read_instancevar
  21.0 ns	read_instancevar_slots
  21.7 ns	read_namedtuple
  27.8 ns	read_boundmethod

Variable and attribute write access:
   6.1 ns	write_local
   7.3 ns	write_nonlocal
  18.9 ns	write_global
  40.7 ns	write_classvar
  36.2 ns	write_instancevar
  26.1 ns	write_instancevar_slots

Data structure read access:
  19.1 ns	read_list
  19.6 ns	read_deque
  20.6 ns	read_dict

Data structure write access:
  22.8 ns	write_list
  23.5 ns	write_deque
  27.8 ns	write_dict

Stack (or queue) operations:
  54.8 ns	list_append_pop
  49.5 ns	deque_append_pop
  49.4 ns	deque_append_popleft

Timing loop overhead:
   0.3 ns	loop_overhead