openstack/neutron
Code Issues Proposed changes

Allocate IPs in bulk requests in separate transactions

Browse Source 
In the ML2 plugin in create_port_bulk method, we are iterating over
list of the ports to be created and do everything for all ports in
single DB transaction (which makes totally sense as this is bulk
request).
But one of the things which was done during that huge transaction was
allocation of the IP addresses for all ports. That action is prone for
race conditions and can fail often, especially when there is no many IP
addresses available in the subnet(s) for the ports.
In case of the error while allocating IP address even for one port from
the whole bulk request, whole create_port_bulk method was retried so
allocations (and everything else) for all ports was reverted and started
from scratch. That takes a lot of time so some requests may be processed
very long time, like e.g. 2-3 minutes in my tests.

To reproduce that issue I did simple script which created network with
/24 subnet and then sent 24 requests to create 10 ports in bulk in each
request. That was in totall 240 ports created in that subnet.
I measured time of the creation of all those ports in the current master
branch (without this patch) and with the patch. Results are like below:

+-----+---------------+------------+---------------------------+
| Run | Master branch | This patch | Simulate bulk by creation |
|     | [mm:ss]       | [mm:ss]    | of 10 ports one by one    |
+-----+---------------+------------+---------------------------+
| 1   | 01:37         | 01:02      | 00:57                     |
| 2   | 02:06         | 00:40      | 01:03                     |
| 3   | 02:08         | 00:41      | 00:59                     |
| 4   | 02:14         | 00:45      | 00:55                     |
| 5   | 01:58         | 00:45      | 00:57                     |
| 6   | 02:37         | 00:53      | 01:05                     |
| 7   | 01:59         | 00:42      | 00:58                     |
| 8   | 02:01         | 00:41      | 00:57                     |
| 9   | 02:39         | 00:42      | 00:55                     |
| 10  | 01:59         | 00:41      | 00:56                     |
+-----+---------------+------------+---------------------------+
| AVG | 00:02:07      | 00:00:45   | 00:58                     |
+-----+---------------+------------+---------------------------+

Closes-Bug: #1954763
Change-Id: I8877c658446fed155130add6f1c69f2772113c27
(cherry picked from commit 82aabb0aa9)
This commit is contained in:
Slawek Kaplonski 2021-12-14 12:44:31 +01:00
parent f90ec2a583
commit 56d2bda51d
3 changed files with 104 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
neutron/db/ipam_pluggable_backend.py
View File

@ -179,6 +179,24 @@ class IpamPluggableBackend(ipam_backend_mixin.IpamBackendMixin):
ipam_driver = driver.Pool.get_instance(None, context)
return ipam_driver.get_subnet(subnet_id)
@db_api.retry_if_session_inactive()
@db_api.CONTEXT_WRITER
def deallocate_ips_from_port(self, context, port, ips):
"""Deallocate set of ips from port.
Deallocate IP addresses previosly allocated for given port.
Format of the ips:
[{
"ip_address": IP.ADDRESS,
"subnet_id": subnet_id
}]
"""
if not ips:
return
ipam_driver = driver.Pool.get_instance(None, context)
self._ipam_deallocate_ips(
context, ipam_driver, port['port'], ips)
def allocate_ips_for_port_and_store(self, context, port, port_id):
# Make a copy of port dict to prevent changing
# incoming dict by adding 'id' to it.
@ -198,19 +216,25 @@ class IpamPluggableBackend(ipam_backend_mixin.IpamBackendMixin):
port_copy['port']['id'] = port_id
network_id = port_copy['port']['network_id']
ips = []
ips = self.allocate_ips_for_port(context, port_copy)
self.store_ip_allocation_for_port(context, ips, network_id, port_copy)
return ips
@db_api.retry_if_session_inactive()
@db_api.CONTEXT_WRITER
def allocate_ips_for_port(self, context, port):
return self._allocate_ips_for_port(context, port)
def store_ip_allocation_for_port(self, context, ips, network_id, port):
try:
ips = self._allocate_ips_for_port(context, port_copy)
for ip in ips:
ip_address = ip['ip_address']
subnet_id = ip['subnet_id']
IpamPluggableBackend._store_ip_allocation(
context, ip_address, network_id,
subnet_id, port_id)
return ips
subnet_id, port['port']['id'])
except Exception:
with excutils.save_and_reraise_exception():
if ips:
ipam_driver = driver.Pool.get_instance(None, context)
if not ipam_driver.needs_rollback():
return
@ -218,7 +242,7 @@ class IpamPluggableBackend(ipam_backend_mixin.IpamBackendMixin):
LOG.debug("An exception occurred during port creation. "
"Reverting IP allocation")
self._safe_rollback(self._ipam_deallocate_ips, context,
ipam_driver, port_copy['port'], ips,
ipam_driver, port['port'], ips,
revert_on_fail=False)
def _allocate_ips_for_port(self, context, port):

53
neutron/plugins/ml2/plugin.py
View File

@ -1506,14 +1506,43 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
return bound_context.current
def allocate_ips_for_ports(self, context, ports):
for port in ports:
port['port']['id'] = (
port['port'].get('id') or uuidutils.generate_uuid())
# Call IPAM to allocate IP addresses
try:
port['ipams'] = self.ipam.allocate_ips_for_port(context, port)
port['ip_allocation'] = (ipalloc_apidef.
IP_ALLOCATION_IMMEDIATE)
except ipam_exc.DeferIpam:
port['ip_allocation'] = (ipalloc_apidef.
IP_ALLOCATION_DEFERRED)
return ports
@utils.transaction_guard
@db_api.retry_if_session_inactive()
def create_port_bulk(self, context, ports):
# TODO(njohnston): Break this up into smaller functions.
port_list = ports.get('ports')
for port in port_list:
self._before_create_port(context, port)
port_list = self.allocate_ips_for_ports(context, port_list)
try:
return self._create_port_bulk(context, port_list)
except Exception:
with excutils.save_and_reraise_exception():
# If any issue happened allocated IP addresses needs to be
# deallocated now
for port in port_list:
self.ipam.deallocate_ips_from_port(
context, port, port['ipams'])
@db_api.retry_if_session_inactive()
def _create_port_bulk(self, context, port_list):
# TODO(njohnston): Break this up into smaller functions.
port_data = []
network_cache = dict()
macs = self._generate_macs(len(port_list))
@ -1565,18 +1594,16 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
# Create the Port object
db_port_obj = ports_obj.Port(context,
mac_address=eui_mac_address,
id=uuidutils.generate_uuid(),
id=port['port']['id'],
**bulk_port_data)
db_port_obj.create()
# Call IPAM to allocate IP addresses
try:
# TODO(njohnston): IPAM allocation needs to be revamped to
# be bulk-friendly.
ips = self.ipam.allocate_ips_for_port_and_store(
context, port, db_port_obj['id'])
# Call IPAM to store allocated IP addresses
ipams = port.pop("ipams")
self.ipam.store_ip_allocation_for_port(
context, ipams, network_id, port)
ipam_fixed_ips = []
for ip in ips:
for ip in ipams:
fixed_ip = ports_obj.IPAllocation(
port_id=db_port_obj['id'],
subnet_id=ip['subnet_id'],
@ -1585,11 +1612,7 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
ipam_fixed_ips.append(fixed_ip)
db_port_obj['fixed_ips'] = ipam_fixed_ips
db_port_obj['ip_allocation'] = (ipalloc_apidef.
IP_ALLOCATION_IMMEDIATE)
except ipam_exc.DeferIpam:
db_port_obj['ip_allocation'] = (ipalloc_apidef.
IP_ALLOCATION_DEFERRED)
db_port_obj['ip_allocation'] = port.pop('ip_allocation')
fixed_ips = pdata.get('fixed_ips')
if validators.is_attr_set(fixed_ips) and not fixed_ips:

21
neutron/tests/unit/plugins/ml2/test_plugin.py
View File

@ -1490,6 +1490,27 @@ class TestMl2PortsV2(test_plugin.TestPortsV2, Ml2PluginV2TestCase):
data, context=ctx)
self.assertFalse(m_upd.called)
def test_create_ports_bulk_ip_allocation_reverted_in_case_of_error(self):
ctx = context.get_admin_context()
with self.network() as net:
plugin = directory.get_plugin()
with mock.patch.object(
plugin, '_create_port_bulk',
side_effect=ml2_exc.MechanismDriverError(
method='create_port_bulk')), \
mock.patch.object(
plugin.ipam,
'deallocate_ips_from_port') as deallocate_mock:
res = self._create_port_bulk(self.fmt, 2, net['network']['id'],
'test', True, context=ctx)
# We expect a 500 as we injected a fault in the plugin
self._validate_behavior_on_bulk_failure(
res, 'ports', webob.exc.HTTPServerError.code)
self.assertEqual(2, deallocate_mock.call_count)
def test_delete_port_no_notify_in_disassociate_floatingips(self):
ctx = context.get_admin_context()
plugin = directory.get_plugin()