def test_load_balanced_read_apps(self, mock):
load_balanced_apps = {
'users': [
('users_db1', 5),
]
}
with override_settings(LOAD_BALANCED_APPS=load_balanced_apps,
DATABASES={
'default': _get_db_config('default'),
'users_db1': _get_db_config('users_db1')
}):
manager = ConnectionManager()
self.assertEqual(
manager.get_load_balanced_read_db_alais(
'users', default="default_option"), 'users_db1')
with override_settings(LOAD_BALANCED_APPS=load_balanced_apps):
# load_balanced_db should be part of settings.DATABASES
with self.assertRaises(AssertionError):
ConnectionManager().get_load_balanced_read_db_alais('users')
# If `LOAD_BALANCED_APPS` is not set for an app, it should point to default kwarg
manager = ConnectionManager()
self.assertEqual(
manager.get_load_balanced_read_db_alais('users',
default='default_option'),
'default_option')
def test_read_load_balancing(self, *args):
reporting_dbs = {
'ucr': {
'WRITE': 'ucr',
'READ': [('ucr', 8), ('other', 1), ('default', 1)]
},
}
with override_settings(REPORTING_DATABASES=reporting_dbs):
manager = ConnectionManager()
self.assertEqual(manager.db_connection_map, {
'default': 'postgresql+psycopg2://:@localhost:5432/default',
'ucr': 'postgresql+psycopg2://:@localhost:5432/ucr',
'other': 'postgresql+psycopg2://:@localhost:5432/other'
})
# test that load balancing works with a 10% margin for randomness
total_requests = 10000
randomness_margin = total_requests * 0.1
total_weighting = sum(db[1] for db in reporting_dbs['ucr']['READ'])
expected = {
alias: weight * total_requests // total_weighting
for alias, weight in reporting_dbs['ucr']['READ']
}
balanced = Counter(manager.get_load_balanced_read_db_alais('ucr') for i in range(total_requests))
for db, requests in balanced.items():
self.assertAlmostEqual(requests, expected[db], delta=randomness_margin)
with override_settings(REPORTING_DATABASES={'default': 'default'}):
manager = ConnectionManager()
self.assertEqual(
['default', 'default', 'default'],
[manager.get_load_balanced_read_db_alais('default') for i in range(3)]
)
def test_load_balanced_read_apps(self, mock):
load_balanced_apps = {
'users': [
('users_db1', 5),
]
}
with override_settings(
LOAD_BALANCED_APPS=load_balanced_apps,
DATABASES = {
'default': _get_db_config('default'),
'users_db1': _get_db_config('users_db1')}):
manager = ConnectionManager()
self.assertEqual(
manager.get_load_balanced_read_db_alais('users', default="default_option"),
'users_db1'
)
with override_settings(LOAD_BALANCED_APPS=load_balanced_apps):
# load_balanced_db should be part of settings.DATABASES
with self.assertRaises(AssertionError):
ConnectionManager().get_load_balanced_read_db_alais('users')
# If `LOAD_BALANCED_APPS` is not set for an app, it should point to default kwarg
manager = ConnectionManager()
self.assertEqual(
manager.get_load_balanced_read_db_alais('users', default='default_option'),
'default_option'
)
def test_read_load_balancing(self, *args):
reporting_dbs = {
'ucr': {
'WRITE': 'ucr',
'READ': [('ucr', 8), ('other', 1), ('default', 1)]
},
}
with override_settings(REPORTING_DATABASES=reporting_dbs):
manager = ConnectionManager()
self.assertEqual(
manager.db_connection_map, {
'default':
'postgresql+psycopg2://:@localhost:5432/default',
'ucr': 'postgresql+psycopg2://:@localhost:5432/ucr',
'other': 'postgresql+psycopg2://:@localhost:5432/other'
})
# test that load balancing works with a 10% margin for randomness
total_requests = 10000
randomness_margin = total_requests * 0.1
total_weighting = sum(db[1] for db in reporting_dbs['ucr']['READ'])
expected = {
alias: weight * total_requests // total_weighting
for alias, weight in reporting_dbs['ucr']['READ']
}
balanced = Counter(
manager.get_load_balanced_read_db_alais('ucr')
for i in range(total_requests))
for db, requests in balanced.items():
self.assertAlmostEqual(requests,
expected[db],
delta=randomness_margin)
with override_settings(REPORTING_DATABASES={'default': 'default'}):
manager = ConnectionManager()
self.assertEqual(['default', 'default', 'default'], [
manager.get_load_balanced_read_db_alais('default')
for i in range(3)
])
def test_standby_filtering(self, *args):
reporting_dbs = {
'ucr_engine': {
'WRITE': 'ucr',
'READ': [('ucr', 8), ('other', 1)]
},
}
with override_settings(REPORTING_DATABASES=reporting_dbs):
# should always return the `other` db since `ucr` has bad replication delay
manager = ConnectionManager()
self.assertEqual(['other', 'other', 'other'], [
manager.get_load_balanced_read_db_alais('ucr_engine')
for i in range(3)
])
def test_standby_filtering(self, *args):
reporting_dbs = {
'ucr_engine': {
'WRITE': 'ucr',
'READ': [('ucr', 8), ('other', 1)]
},
}
with override_settings(REPORTING_DATABASES=reporting_dbs):
# should always return the `other` db since `ucr` has bad replication delay
manager = ConnectionManager()
self.assertEqual(
['other', 'other', 'other'],
[manager.get_load_balanced_read_db_alais('ucr_engine') for i in range(3)]
)