Fix crash caused by concurrent ObjectSpace.dump_all calls

Since the callback defined in the objspace module might give up the GVL,
we need to make sure the right cr->mfd value is set back after the GVL
is re-obtained.

1 files changed, 8 insertions, 0 deletions

diff --git a/test/objspace/test_objspace.rb b/test/objspace/test_objspace.rb
index 1f1709fb76..1a8d7a24ba 100644
--- a/test/objspace/test_objspace.rb
+++ b/test/objspace/test_objspace.rb
@@ -918,6 +918,14 @@ class TestObjSpace < Test::Unit::TestCase
     assert_equal 2, ObjectSpace.dump_shapes(output: :string, since: RubyVM.stat(:next_shape_id) - 2).lines.size
   end
 
+  def test_dump_all_in_parallel_bug_19922
+    dump_ten_times = ->() { 10.times { ObjectSpace.dump_all.tap { _1.close } } }
+    t = Thread.new { dump_ten_times.call }
+    dump_ten_times.call
+    t.value
+    # Bug #19922 would cause this test to crash.
+  end
+
   private
 
   def utf8_❨╯°□°❩╯︵┻━┻