io.c: write a newline together

* io.c (rb_io_puts): write a newline together at once for each
  argument.  based on the patch by rohitpaulk (Rohit Kuruvilla) at
  [ruby-core:83508].  [Feature #14042]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60417 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 13 insertions, 0 deletions

diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index c7de83784b..a32369eca5 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -2445,6 +2445,19 @@ End
     end)
   end
 
+  def test_puts_parallel
+    pipe(proc do |w|
+      threads = []
+      100.times do
+        threads << Thread.new { w.puts "hey" }
+      end
+      threads.each(&:join)
+      w.close
+    end, proc do |r|
+      assert_equal("hey\n" * 100, r.read)
+    end)
+  end
+
   def test_display
     pipe(proc do |w|
       "foo".display(w)