Django API sudden degrade in performance - django

Question

I am working on a project where all REST API are implemented in django and UI is taken care by Vue.js. Since last week our dev and qa environments are facing long TTFB response time even for simple select queries to Postgres Database. To investigate this I added some logs to see how much time it takes to execute the query. Here is the code below
import datetime
from django.core.signals import request_started, request_finished
from django.conf import settings
class TenantListViewSet(APIView):
"""
API endpoint that returns all tenants present in member_master table.
"""
#ldap_login_required
#method_decorator(login_required)
def get(self, request):
settings.get_start_time = datetime.datetime.now()
print(f'Total time from started to get begin {settings.get_start_time-settings.request_start_time}')
errors = list()
messages = list()
try:
settings.db_query_start_time = datetime.datetime.now()
tenant_list_objects = list(MemberMaster.objects.all())
print(MemberMaster.objects.all().explain(verbose=True, analyze=True))
settings.db_query_end_time = datetime.datetime.now()
print(f'Total time taken to execute DB query {settings.db_query_end_time-settings.db_query_start_time}')
db_start = datetime.datetime.now()
serializer = MemberMasterSerializer(tenant_list_objects, many=True)
db_end = datetime.datetime.now()
print(f'Total time taken to serialize data {db_end-db_start}')
tenant_list = serializer.data
response = result_service("tenant_list", tenant_list, errors, messages)
settings.get_end_time = datetime.datetime.now()
print(f'Total time taken to finish get call {settings.get_end_time-settings.get_start_time}')
return JsonResponse(response.result["result_data"], status=response.result["status_code"])
except Exception as e:
if isinstance(e, dict) and 'messages' in e:
errors.extend(e.messages)
else:
errors.extend(e.args)
response = result_service("tenant_list", [], errors, messages)
return JsonResponse(response.result['result_data'], status=400)
def started(sender, **kwargs): # First method that gets invoked when GET API is called
settings.request_start_time = datetime.datetime.now()
def finished(sender, **kwargs): # Last method that gets invoked before sending the response back
return_from_get = datetime.datetime.now() - settings.get_end_time
total = datetime.datetime.now() - settings.request_start_time
print(f'Total time from get return to finished {return_from_get}')
print(f'API total time {total}')
request_started.connect(started) # Added hooks to django signal to check the time
request_finished.connect(finished) # Added hooks to django signal to check the time
These are the logs for the above API which has 126 rows in the table member_master
Total time taken to check user is authenticated 0:00:00.000374
Total time from started to get begin 0:00:02.060007
Seq Scan on member_master (cost=0.00..11.20 rows=120 width=634) (actual time=0.004..0.032 rows=126 loops=1)
Output: member_master_id, member_name, mbr_sk, mbr_uid, member_guid
Planning time: 0.028 ms
Execution time: 0.065 ms
Total time taken to execute DB query 0:00:02.026839
Total time taken to serialize data 0:00:00.000132
Total time taken to finish get call 0:00:02.267809
Total time from get return to finished 0:00:00.001454
API total time 0:00:04.329273
As you can see the execution time of the query itself is 0.065 ms but the time taken by django is 2 seconds. I tried to use raw query instead of list(MemberMaster.objects.all()) and the issue still exist. Also I am not able to reproduce this in my local environment but happens in both dev and qa environments. Hence I did not use django debug toolbar. No changes were made recently to any model and this issue exist for all API's in the project. Any idea what might be the issue here?
Model code
class MemberMaster(models.Model):
member_master_id = models.AutoField(primary_key=True)
member_name = models.CharField(max_length=256)
mbr_sk = models.ForeignKey('Member', on_delete=models.DO_NOTHING, db_column='mbr_sk')
mbr_uid = models.CharField(max_length=32, blank=True, null=True)
member_guid = models.UUIDField(blank=True, null=True)
class Meta:
managed = False
db_table = 'member_master'
app_label = 'queryEditor'