export-memory-test.patch

diff --git a/app/serializers/export/others_data_serializer.rb b/app/serializers/export/others_data_serializer.rb
index 96a819c..8769545 100644
--- a/app/serializers/export/others_data_serializer.rb
+++ b/app/serializers/export/others_data_serializer.rb
@@ -11,24 +11,55 @@ module Export
     # Authors of posts where we participated and authors are not in contacts
     has_many :non_contact_authors, each_serializer: PersonMetadataSerializer
 
+    def initialize(user_id)
+      @user_id = user_id
+      super(object)
+    end
+
     private
 
+    def object
+      User.find(@user_id)
+    end
+
+    module AlwaysBeFlat
+      def map(*, &block)
+        flat_map {|element| element.map(&block)}
+      end
+    end
+
     def relayables
       %i[comments likes poll_participations].map {|relayable|
-        others_relayables.send(relayable)
-      }.sum
+        others_relayables.send(relayable).find_each(batch_size: 20)
+      }.extend AlwaysBeFlat
     end
 
     def others_relayables
       @others_relayables ||= Diaspora::Exporter::OthersRelayables.new(object.person_id)
     end
 
+    def posts_with_activity
+      Diaspora::Exporter::PostsWithActivity.new(object).query
+    end
+
+    module AlwaysBeFlatAndLazy
+      def map(*, &block)
+        flat_map {|element| element.map(&block)}.force
+      end
+    end
+
     def posts
-      @posts ||= Diaspora::Exporter::PostsWithActivity.new(object).query
+      posts_with_activity.pluck(:id).each_slice(20).lazy.map {|ids|
+        Post.find(ids)
+      }.extend(AlwaysBeFlatAndLazy)
     end
 
     def non_contact_authors
-      Diaspora::Exporter::NonContactAuthors.new(posts, object).query
+      Diaspora::Exporter::NonContactAuthors.new(posts_with_activity, object).query.find_each(batch_size: 50)
+    end
+
+    def serializable_data
+      {}
     end
   end
 end
diff --git a/app/serializers/export/own_post_serializer.rb b/app/serializers/export/own_post_serializer.rb
index 150ecd4..39e12d8 100644
--- a/app/serializers/export/own_post_serializer.rb
+++ b/app/serializers/export/own_post_serializer.rb
@@ -27,7 +27,7 @@ module Export
     end
 
     def excluded_subscription_key
-      entity.public ? :subscribed_users_ids : :subscribed_pods_uris
+      object.public? ? :subscribed_users_ids : :subscribed_pods_uris
     end
   end
 end
diff --git a/app/serializers/export/user_serializer.rb b/app/serializers/export/user_serializer.rb
index 09f26d3..812be23 100644
--- a/app/serializers/export/user_serializer.rb
+++ b/app/serializers/export/user_serializer.rb
@@ -18,10 +18,37 @@ module Export
 
     has_many :relayables, each_serializer: Export::OwnRelayablesSerializer
 
+    def initialize(user_id)
+      @user_id = user_id
+      super(object)
+    end
+
     private
 
+    def object
+      User.find(@user_id)
+    end
+
+    def posts
+      object.posts.find_each(batch_size: 20)
+    end
+
+    def contacts
+      object.contacts.find_each(batch_size: 100)
+    end
+
+    module AlwaysBeFlat
+      def map(*, &block)
+        flat_map {|element| element.map(&block)}
+      end
+    end
+
     def relayables
-      [*comments, *likes, *poll_participations]
+      [comments, likes, poll_participations].map {|relayable|
+        relayable.find_each(batch_size: 20)
+      }.tap {|relayables|
+        relayables.extend AlwaysBeFlat
+      }
     end
 
     %i[comments likes poll_participations].each {|collection|
@@ -45,5 +72,9 @@ module Export
     def post_subscriptions
       Post.subscribed_by(object).pluck(:guid)
     end
+
+    def serializable_data
+      {}
+    end
   end
 end
diff --git a/app/serializers/federation_entity_serializer.rb b/app/serializers/federation_entity_serializer.rb
index 0458fc7..cafe142 100644
--- a/app/serializers/federation_entity_serializer.rb
+++ b/app/serializers/federation_entity_serializer.rb
@@ -11,6 +11,6 @@ class FederationEntitySerializer < ActiveModel::Serializer
   end
 
   def entity
-    @entity ||= Diaspora::Federation::Entities.build(object)
+    Diaspora::Federation::Entities.build(object)
   end
 end
diff --git a/lib/diaspora/exporter.rb b/lib/diaspora/exporter.rb
index 2c9e279..3586af9 100644
--- a/lib/diaspora/exporter.rb
+++ b/lib/diaspora/exporter.rb
@@ -20,8 +20,8 @@ module Diaspora
 
     def full_archive
       {version: SERIALIZED_VERSION}
-        .merge(Export::UserSerializer.new(@user).as_json)
-        .merge(Export::OthersDataSerializer.new(@user).as_json)
+        .merge(Export::UserSerializer.new(@user.id).as_json)
+        .merge(Export::OthersDataSerializer.new(@user.id).as_json)
     end
   end