Eagerly close Dalli connections in MemCachedStoreTest

Otherwise the test suite is flaky when ran repeatedly
on the same machine because of file descriptors exhaustion.

Author: byroot

activesupport/test/cache/stores/mem_cache_store_test.rb

@@ -36,7 +36,9 @@ class MemCacheStoreTest < ActiveSupport::TestCase
   end
 
   def lookup_store(options = {})
-    ActiveSupport::Cache.lookup_store(*store, { namespace: @namespace }.merge(options))
+    cache = ActiveSupport::Cache.lookup_store(*store, { namespace: @namespace }.merge(options))
+    (@_stores ||= []) << cache
+    cache
   end
 
   def setup
@@ -48,6 +50,15 @@ def setup
     @cache.logger = ActiveSupport::Logger.new(File::NULL)
   end
 
+  def after_teardown
+    stores, @_stores = @_stores, []
+    stores.each do |store|
+      # Eagerly closing Dalli connection avoid file descriptor exhaustion.
+      # Otherwise the test suite is flaky when ran repeatedly
+      store.instance_variable_get(:@data).close
+    end
+  end
+
   include CacheStoreBehavior
   include CacheStoreVersionBehavior
   include CacheStoreCoderBehavior