nickva commented on issue #4650:
URL: https://github.com/apache/couchdb/issues/4650#issuecomment-1599233435
I tried to compare the two approaches:
```erlang
-module(upstats).
-export([go/0, go/1, go/2]).
go() ->
go(1000, 10000).
go(N) ->
go(N, 10000).
go(N, X) ->
T0 = erlang:monotonic_time(),
Workers = [spawn_monitor(fun() ->
rand:seed(default, os:timestamp()),
upstat(X)
end) || _ <- lists:seq(1, N)],
{_Pids, Refs} = lists:unzip(Workers),
WorkersSet = sets:from_list(Refs, [{version,2}]),
ok = wait_workers(WorkersSet),
Dt = erlang:monotonic_time() - T0,
erlang:convert_time_unit(Dt, native, millisecond).
upstat(0) ->
ok;
upstat(Times) ->
Hist = case rand:uniform(5) of
1 -> [couchdb, request_time];
2 -> [couchdb, dbinfo];
3 -> [couchdb, httpd, bulk_docs];
4 -> [fsync, time];
5 -> [couchdb, db_open_time]
end,
couch_stats:update_histogram(Hist, 100),
upstat(Times - 1).
wait_workers(Workers) when is_map(Workers) ->
case sets:size(Workers) of
0 ->
ok;
_ ->
receive
{'DOWN', Ref, process, _, normal} ->
Workers1 = sets:del_element(Ref, Workers),
wait_workers(Workers1);
{'DOWN', Ref, process, _, Err} ->
Workers1 = sets:del_element(Ref, Workers),
io:format("~n worker ~p crashed: ~p~n", [Ref, Err]),
wait_workers(Workers1)
end
end.
```
With an example counters update:
``````erlang
-module(upstats_counter).
-export([go/0, go/1, go/2]).
go() ->
go(1000, 10000).
go(N) ->
go(N, 10000).
go(N, X) ->
Ref = counters:new(1024, [write_concurrency]),
persistent_term:put(term, Ref),
T0 = erlang:monotonic_time(),
Workers = [spawn_monitor(fun() ->
rand:seed(default, os:timestamp()),
upstat(X)
end) || _ <- lists:seq(1, N)],
{_Pids, Refs} = lists:unzip(Workers),
WorkersSet = sets:from_list(Refs, [{version,2}]),
ok = wait_workers(WorkersSet),
Dt = erlang:monotonic_time() - T0,
erlang:convert_time_unit(Dt, native, millisecond).
upstat(0) ->
ok;
upstat(Times) ->
Ref = persistent_term:get(term),
counters:add(Ref, rand:uniform(1024), 100),
upstat(Times - 1).
wait_workers(Workers) when is_map(Workers) ->
case sets:size(Workers) of
0 ->
ok;
_ ->
receive
{'DOWN', Ref, process, _, normal} ->
Workers1 = sets:del_element(Ref, Workers),
wait_workers(Workers1);
{'DOWN', Ref, process, _, Err} ->
Workers1 = sets:del_element(Ref, Workers),
io:format("~n worker ~p crashed: ~p~n", [Ref, Err]),
wait_workers(Workers1)
end
end.
```
```erlang
([email protected])18> upstats_counter:go(50000, 1000).
1385
([email protected])19> upstats_counter:go(50000, 1000).
1425
([email protected])20> upstats_counter:go(50000, 1000).
1427
([email protected])21> upstats_counter:go(50000, 1000).
1438
([email protected])22> upstats:go(50000, 1000).
15131
([email protected])23> upstats:go(50000, 1000).
16075
([email protected])24> upstats:go(50000, 1000).
14869
```
Even with folsom front loading and updating only 1024 values per second it's
till 10x slower!
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