diff options
Diffstat (limited to 'lib/stdlib/test/io_SUITE.erl')
| -rw-r--r-- | lib/stdlib/test/io_SUITE.erl | 46 |
1 files changed, 44 insertions, 2 deletions
diff --git a/lib/stdlib/test/io_SUITE.erl b/lib/stdlib/test/io_SUITE.erl index 3a76275f31..2203dd8f51 100644 --- a/lib/stdlib/test/io_SUITE.erl +++ b/lib/stdlib/test/io_SUITE.erl @@ -30,7 +30,8 @@ io_fread_newlines/1, otp_8989/1, io_lib_fread_literal/1, printable_range/1, io_lib_print_binary_depth_one/1, otp_10302/1, otp_10755/1, - otp_10836/1, io_lib_width_too_small/1]). + otp_10836/1, io_lib_width_too_small/1, + io_with_huge_message_queue/1]). -export([pretty/2]). @@ -70,7 +71,7 @@ all() -> io_fread_newlines, otp_8989, io_lib_fread_literal, printable_range, io_lib_print_binary_depth_one, otp_10302, otp_10755, otp_10836, - io_lib_width_too_small]. + io_lib_width_too_small, io_with_huge_message_queue]. groups() -> []. @@ -2219,3 +2220,44 @@ io_lib_width_too_small(Config) -> "**" = lists:flatten(io_lib:format("~2.3w", [3.14])), "**" = lists:flatten(io_lib:format("~2.5w", [3.14])), ok. + +%% Test that the time for a huge message queue is not +%% significantly slower than with an empty message queue. +io_with_huge_message_queue(Config) when is_list(Config) -> + case test_server:is_native(gen) of + true -> + {skip, + "gen is native - huge message queue optimization " + "is not implemented"}; + false -> + do_io_with_huge_message_queue(Config) + end. + +do_io_with_huge_message_queue(Config) -> + PrivDir = ?privdir(Config), + File = filename:join(PrivDir, "slask"), + {ok, F1} = file:open(File, [write]), + + {Time,ok} = timer:tc(fun() -> writes(1000, F1) end), + + [self() ! {msg,N} || N <- lists:seq(1, 500000)], + erlang:garbage_collect(), + {NewTime,ok} = timer:tc(fun() -> writes(1000, F1) end), + file:close(F1), + io:format("Time for empty message queue: ~p", [Time]), + io:format("Time for huge message queue: ~p", [NewTime]), + + IsCover = test_server:is_cover(), + case (NewTime+1) / (Time+1) of + Q when Q < 10; IsCover -> + ok; + Q -> + io:format("Q = ~p", [Q]), + ?t:fail() + end, + ok. + +writes(0, _) -> ok; +writes(N, F1) -> + file:write(F1, "hello\n"), + writes(N - 1, F1). |