thread.c (do_select): fix leak on exception

When do_select is interrupted and raise happens from
RUBY_VM_CHECK_INTS_BLOCKING, the original FD sets we copied
do not get freed, leading to a memory leak.  Wrap up all the
FD sets into a Ruby object to ensure the GC can release an
allocations made for rb_fdset_t.

This leak existed since Ruby 2.0.0 (r36430)

[Bug #14929]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64007 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 16 insertions, 0 deletions

diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index a6a8e78209..1c45787648 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -3800,4 +3800,20 @@ __END__
       assert_equal 'done', noex.value ,'r63216'
     end
   end
+
+  def test_select_leak
+    assert_no_memory_leak([], <<-"end;", <<-"end;", rss: true, timeout: 30)
+      r, w = IO.pipe
+      rset = [r]
+      wset = [w]
+      Thread.new { IO.select(rset, wset, nil, 0) }.join
+    end;
+      200000.times do
+        th = Thread.new { IO.select(rset, wset) }
+        Thread.pass until th.stop?
+        th.kill
+        th.join
+      end
+    end;
+  end
 end