Bug ID 544902: tcp_half_open health-monitor type can impose high CPU load in control plane

Last Modified: May 29, 2024

Affected Product(s):
BIG-IP LTM(all modules)

Known Affected Versions:
13.0.0, 13.0.0 HF1, 13.0.0 HF2, 13.0.0 HF3, 13.0.1, 13.1.0,,,,,,,,, 13.1.1,,,,, 13.1.3,,,,,,, 13.1.4,, 13.1.5,, 14.0.0,,,,,, 14.0.1,, 14.1.5,,,,,, 15.0.0, 15.0.1,,,,, 15.1.6,, 15.1.7, 15.1.8,,, 15.1.9,, 15.1.10,,,, 16.1.3,,,,,, 16.1.4,,,

Opened: Sep 09, 2015

Severity: 3-Major


Performance measurements may show an unexpectedly high CPU load in the control plane, especially by the "bigd" process.


In severe cases, BIG-IP may indicate an erroneous status for pool members, or other performance-related control-plane problems may be seen.


Many pool members are being monitored using the "tcp_half_open" health-monitor type.


Unless the resources being monitored are among the few rare types which require "tcp_half_open", change the monitoring to a different health monitor, such as simple "tcp".

Fix Information


Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips