DRF pagination mixing page_size of multiple views

[anshukch]

We're using Django 1.11.29. The DRF we use is customised after v3.9.4 release. The customisation is bypassing KeyError while serializer pop in ReturnDict and ReturnList classes in serializer_helpers.py#L19. This is needed to support voluptous for our tests.

Following is our pagination class

class CustomPagination(pagination.PageNumberPagination):
    page_size_query_param = 'page_size'
    page_query_param = 'page'
    page_size = 10
    max_page_size = 100

    def get_paginated_response(self, data, extra_data=None):
        response = {
            'next': self.get_next_link(),
            'previous': self.get_previous_link(),
            'count': self.page.paginator.count,
            'results': data
        }
        if extra_data is not None:
            response.update(extra_data)
        return Response(response)

Both DEFAULT_PAGINATION_CLASS and PAGE_SIZE(equal to 9) are specified in settings.py as well.

Problem

There are two views(viewsets.ReadOnlyModelViewSet actually). One has a page_size=3 and another has a page_size=4. When the client loads a page, both of these paginated APIs are called. While rendering the request, the APIs are mixing the page_sizes. The first response has correct page sizes. But some of the subsequent responses are returning responses with page_size of 4 and 3 respectively. The mixup is being detected here in pagination.py#L194. I wasn't able to debug this further. Please advise.