Merge pull request #20175 from eugeneius/copy_schema_cache_after_fork

Add schema cache to new connection pool after fork

activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb

@@ -933,7 +933,9 @@ def pool_for(owner)
             # A connection was established in an ancestor process that must have
             # subsequently forked. We can't reuse the connection, but we can copy
             # the specification and establish a new connection with it.
-            establish_connection owner, ancestor_pool.spec
+            establish_connection(owner, ancestor_pool.spec).tap do |pool|
+              pool.schema_cache = ancestor_pool.schema_cache if ancestor_pool.schema_cache
+            end
           else
             owner_to_pool[owner.name] = nil
           end

activerecord/test/cases/connection_adapters/connection_handler_test.rb

@@ -46,6 +46,52 @@ def test_retrieve_connection_pool_uses_superclass_pool_after_subclass_establish_
       def test_connection_pools
         assert_equal([@pool], @handler.connection_pools)
       end
+
+      if Process.respond_to?(:fork)
+        def test_connection_pool_per_pid
+          object_id = ActiveRecord::Base.connection.object_id
+
+          rd, wr = IO.pipe
+          rd.binmode
+          wr.binmode
+
+          pid = fork {
+            rd.close
+            wr.write Marshal.dump ActiveRecord::Base.connection.object_id
+            wr.close
+            exit!
+          }
+
+          wr.close
+
+          Process.waitpid pid
+          assert_not_equal object_id, Marshal.load(rd.read)
+          rd.close
+        end
+
+        def test_retrieve_connection_pool_copies_schema_cache_from_ancestor_pool
+          @pool.schema_cache = @pool.connection.schema_cache
+          @pool.schema_cache.add('posts')
+
+          rd, wr = IO.pipe
+          rd.binmode
+          wr.binmode
+
+          pid = fork {
+            rd.close
+            pool = @handler.retrieve_connection_pool(@klass)
+            wr.write Marshal.dump pool.schema_cache.size
+            wr.close
+            exit!
+          }
+
+          wr.close
+
+          Process.waitpid pid
+          assert_equal @pool.schema_cache.size, Marshal.load(rd.read)
+          rd.close
+        end
+      end
     end
   end
 end

activerecord/test/cases/connection_management_test.rb

@@ -26,29 +26,6 @@ def setup
         assert ActiveRecord::Base.connection_handler.active_connections?
       end
 
-      if Process.respond_to?(:fork)
-        def test_connection_pool_per_pid
-          object_id = ActiveRecord::Base.connection.object_id
-
-          rd, wr = IO.pipe
-          rd.binmode
-          wr.binmode
-
-          pid = fork {
-            rd.close
-            wr.write Marshal.dump ActiveRecord::Base.connection.object_id
-            wr.close
-            exit!
-          }
-
-          wr.close
-
-          Process.waitpid pid
-          assert_not_equal object_id, Marshal.load(rd.read)
-          rd.close
-        end
-      end
-
       def test_app_delegation
         manager = ConnectionManagement.new(@app)