From: "nobu (Nobuyoshi Nakada) via ruby-core" <ruby-core@...>
Date: 2023-02-24T14:34:57+00:00
Subject: [ruby-core:112570] [Ruby master Bug#19461] Time.local performance tanks in forked process (on macOS only?)

Issue #19461 has been updated by nobu (Nobuyoshi Nakada).

File localtime_test.c added

Seems unrelated to Ruby.

```
$ sw_vers 
ProductName:		macOS
ProductVersion:		13.2.1
BuildVersion:		22D68

$ clang localtime_test.c && ./a.out && ./a.out r
Measuring localtime
In parent
  monotonic = 0.002226000
  cputime = 0.001949000
In child
  monotonic = 0.581383000
  cputime = 0.580938000
Measuring localtime_r
In parent
  monotonic = 0.002409000
  cputime = 0.001967000
In child
  monotonic = 0.587200000
  cputime = 0.586385000
```

----------------------------------------
Bug #19461: Time.local performance tanks in forked process (on macOS only?)
https://bugs.ruby-lang.org/issues/19461#change-102019

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
The following program demonstrates a performance regression in forked child processes when invoking `Time.local`:

```ruby
require 'benchmark'
require 'time'

def sir_local_alot
  result = Benchmark.measure do
    10_000.times do
      tm = ::Time.local(2023)
    end
  end
  $stderr.puts result
end

sir_local_alot

pid = fork do
  sir_local_alot
end

Process.wait(pid)
```

On Linux the performance is similar, but on macOS, the performance is over 100x worse on my M1 laptop.


---Files--------------------------------
localtime_test.c (1.28 KB)


-- 
https://bugs.ruby-lang.org/
 ______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
 ruby-core info -- https://ml.ruby-lang.org/mailman3/postorius/lists/ruby-core.ml.ruby-lang.org/