Django REST framework, serializer performance degradation - django

Question

I have a simple list API view which is using serializer:
class ListCreateDeploymentView(
generics.ListCreateAPIView
):
permission_classes = (IsAuthenticated,)
renderer_classes = [JSONRenderer]
content_negotiation_class = IgnoreClientContentNegotiation
def get_queryset(self):
queryset = Deployment.objects.all()
return queryset
def list(self, request, version):
queryset = self.get_queryset()
serializer = DeploymentListSerializer(queryset, many=True)
data = serializer.data
return Response(data)
Serializer is simple:
class DeploymentListSerializer(serializers.ModelSerializer):
class Meta:
model = Deployment
fields = (
'id',
'query',
'config',
'started_at',
'finished_at',
'status',
'project',
)
read_only_fields = (
'id',
'query',
'config',
'started_at',
'finished_at',
'status',
'project',
)
Then I do a local load test with 10 users and delay 1s each execution so target rps is 10 req/s and see this picture with a clear performance degradation after few minutes
What means If I open 10 tabs in browser with ajax request every second to this endpoint the server will get unresponsive in a minute:
Then I used recommendations from here and used read-only regular serializer:
class DeploymentListSerializer(serializers.ModelSerializer):
# commands = CommandListSerializer(read_only=True, many=True)
# clients = ClientSimpleSerializer(read_only=True, many=True)
id = serializers.IntegerField(read_only=True)
query = serializers.CharField(read_only=True)
config = serializers.CharField(read_only=True)
started_at = serializers.DateTimeField(read_only=True)
finished_at = serializers.DateTimeField(read_only=True)
status = serializers.IntegerField(read_only=True)
project = serializers.CharField(read_only=True)
class Meta:
model = Deployment
fields = (
'id',
'query',
'config',
'started_at',
'finished_at',
'status',
'project',
)
The situation became even worse:
Finally, if I remove serialization:
def list(self, request, version):
queryset = self.get_queryset()
data = queryset.values(
'id', 'query', 'config', 'started_at', 'finished_at',
'status', 'project'
)
return Response(data)
And do same test again the performance getting much better(expected), but also stable:
The problem is I need serialization because the task is a bit more complicated and I need to return nested objects, but it`s already falling on such an easy example.
What do I wrong?
UPD: same bad picture if I use the function-based view:
#api_view(['GET'])
def get_deployments(request, version):
queryset = Deployment.objects.all()
serializer = DeploymentCreateSerializer(queryset, many=True)
data = serializer.data
return Response(data)