thread.c: deadlock in backtrace

* thread.c (unblock_function_set): check interrupts just once
  during raising exceptions, as they are deferred since r16651.
  [ruby-core:85939] [Bug #14577]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62673 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 22 insertions, 0 deletions

diff --git a/test/ruby/test_exception.rb b/test/ruby/test_exception.rb
index 08e581d4f4..bb70bf508f 100644
--- a/test/ruby/test_exception.rb
+++ b/test/ruby/test_exception.rb
@@ -1200,6 +1200,28 @@ $stderr = $stdout; raise "\x82\xa0"') do |outs, errs, status|
     end;
   end
 
+  def test_blocking_backtrace
+    assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
+    begin;
+      class Bug < RuntimeError
+        def backtrace
+          IO.readlines(IO::NULL)
+        end
+      end
+      bug = Bug.new '[ruby-core:85939] [Bug #14577]'
+      n = 10000
+      i = 0
+      n.times do
+        begin
+          raise bug
+        rescue Bug
+          i += 1
+        end
+      end
+      assert_equal(n, i)
+    end;
+  end
+
   def test_wrong_backtrace
     assert_separately([], "#{<<-"begin;"}\n#{<<-"end;"}")
     begin;