Hello, I managed to reproduce this in a test environment with 1000 dhcp enabled subnets. Python 3.6 is faster (or at least chattier), but the same can still be seen. Same 100-300ms exec delays with rootwrap visible. RH with collections+pip for deps, so paths look interesting. 2019-10-28 15:51:02.510 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-0ac39b4a-4517-466c-8857-54e4c9e8d416', 'ip', '-o', 'link', 'show', 'tapd1a110f8-06'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:02.807 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-01f0c21c-af3f-483f-b44c-77fa39862430', 'ip', '-o', 'link', 'show', 'tap04086413-55'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:03.088 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-0ad0ae7b-3632-48be-9322-1177a82c17a6', 'ip', '-o', 'link', 'show', 'tapef523a14-5e'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:03.383 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-05063b4c-a030-4b92-af53-f47b19b64b9b', 'ip', '-o', 'link', 'show', 'tap9889d494-86'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:03.688 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-070c6f88-5000-4a01-a100-36c914a6e219', 'ip', '-o', 'link', 'show', 'tap0e6dc9db-49'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:03.981 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-04b2ae20-eecf-481b-bf63-a8809b454e97', 'ip', '-o', 'link', 'show', 'tapcc06a136-82'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:04.270 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-0972f344-e157-48ec-a94d-25e5b63fc517', 'ip', '-o', 'link', 'show', 'tap2b239e1c-a7'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:04.555 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-010bf420-3113-4a5d-9598-7726777468f2', 'ip', 'link', 'set', 'tapde888fdc-0e', 'up'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:04.857 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-0840e054-f880-4404-a0e6-5c96a3088626', 'ip', '-o', 'link', 'show', 'tap49ac8943-28'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:05.147 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-04966f5a-c3c1-4cc5-a4f7-62b557537f87', 'ip', '-o', 'link', 'show', 'tap609ca686-fa'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:05.439 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-05b26808-3df8-4683-b411-5f9075fc7ef8', 'ip', '-o', 'link', 'show', 'tapedcbc041-06'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:05.728 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-034dd292-6d6e-40dc-b244-8f9c479221a1', 'ip', '-o', 'link', 'show', 'tape075be73-ab'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:06.025 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-07def51c-c5e6-48e3-9214-1eba474f56d6', 'ip', '-o', 'link', 'show', 'tapdeae5df9-b7'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:06.333 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-042d7584-cecf-49d9-97b0-8a933497da49', 'ip', '-o', 'link', 'show', 'tap481328e6-de'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:06.641 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-05cb1d8e-b5c1-4b2c-9370-9777bdee41aa', 'ip', '-o', 'link', 'show', 'tapf541cc03-75'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:06.943 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-04254991-661e-44a7-a49c-f026db42f693', 'ip', '-o', 'link', 'show', 'tapf6bd4ed0-22'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:07.251 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-019da491-de9c-4d14-b0d8-e4c093bd3813', 'ip', 'link', 'set', 'tap0af13c92-d6', 'up'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:07.535 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-0403d743-5ff0-4064-9cdc-09661a078556', 'ip', '-o', 'link', 'show', 'tap51e1d9ca-92'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:07.823 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-0b0e7a6d-770b-44de-b174-cb09a458a0d7', 'ip', '-o', 'link', 'show', 'tap535f5d74-15'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:08.118 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-02cbfa70-6954-45ce-a2cd-5ba28e876069', 'ip', '-o', 'link', 'show', 'tap49eda1ea-38'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:08.406 680502 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-07a85f5e-243b-4e38-8834-6a000f25a771', 'ip', '-o', 'link', 'show', 'tap5a01ad8b-5b'] execute_rootwrap_daemon /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:103 2019-10-28 15:51:08.435 680502 ERROR neutron.agent.linux.dhcp [-] Failed to start DHCP process for network 00372a08-640d-445a-88f9-03ae7c37f3ab: neutron.common.utils.WaitTimeout: Timed out after 60 seconds 2019-10-28 15:51:08.660 680502 DEBUG neutron.agent.linux.utils [-] Unable to access /var/lib/neutron/external/pids/00372a08-640d-445a-88f9-03ae7c37f3ab.pid get_value_from_file /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:250 2019-10-28 15:51:08.660 680502 DEBUG neutron.agent.linux.utils [-] Unable to access /var/lib/neutron/external/pids/00372a08-640d-445a-88f9-03ae7c37f3ab.pid get_value_from_file /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:250 2019-10-28 15:51:08.661 680502 DEBUG neutron.agent.linux.external_process [-] No process started for 00372a08-640d-445a-88f9-03ae7c37f3ab disable /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/external_process.py:118 2019-10-28 15:51:08.661 680502 INFO neutron.agent.dhcp.agent [-] Finished network 00372a08-640d-445a-88f9-03ae7c37f3ab dhcp configuration 2019-10-28 15:51:08.663 680502 ERROR neutron.agent.linux.dhcp [-] Failed to start DHCP process for network 004ed235-cef1-42db-822a-f60b3170e54d: neutron.common.utils.WaitTimeout: Timed out after 60 seconds 2019-10-28 15:51:08.664 680502 DEBUG neutron.agent.linux.utils [-] Unable to access /var/lib/neutron/external/pids/004ed235-cef1-42db-822a-f60b3170e54d.pid get_value_from_file /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:250 2019-10-28 15:51:08.664 680502 DEBUG neutron.agent.linux.utils [-] Unable to access /var/lib/neutron/external/pids/004ed235-cef1-42db-822a-f60b3170e54d.pid get_value_from_file /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/utils.py:250 2019-10-28 15:51:08.665 680502 DEBUG neutron.agent.linux.external_process [-] No process started for 004ed235-cef1-42db-822a-f60b3170e54d disable /opt/rh/rh-python36/root/usr/lib/python3.6/site-packages/neutron/agent/linux/external_process.py:118 2019-10-28 15:51:08.665 680502 INFO neutron.agent.dhcp.agent [-] Finished network 004ed235-cef1-42db-822a-f60b3170e54d dhcp configuration 2019-10-28 15:51:08.665 680502 ERROR neutron.agent.linux.dhcp [-] Failed to start DHCP process for network 00dda134-bcac-4953-aa2b-4314303f5b40: neutron.common.utils.WaitTimeout: Timed out after 60 seconds I didn't yet check the proposal Brian linked. Cheers.