Bug ID 450019: Making LB::prime execute asynchronously if the server side flow is congested.

Last Modified: Oct 06, 2020

Bug Tracker

Affected Product:  See more info
BIG-IP LTM(all modules)

Known Affected Versions:
11.5.1, 11.5.0, 11.4.1, 11.4.0, 11.3.0, 11.2.1, 11.2.0, 11.1.0

Fixed In:
11.6.0, 11.5.1 HF5, 11.4.1 HF4, 11.2.1 HF11

Opened: Feb 24, 2014
Severity: 3-Major
Related AskF5 Article:


TMM cores with the log message 'panic: Invalid Tcl recursion' and a stack trace.


When LB::prime command executes, the queued messages are processed, resulting in a core as these messages are not using the correct Tcl context. Rarely, a crash causes the pool members go down.


This crash rarely occurs when the following conditions are met. 1. SIP on TCP profile. 2. Triggering LB::Prime irule every few seconds on CLIENT_ACCEPTED event. 3. Server-side congestion due to a large amount of traffic. 4. Large queues of undelivered proxied messages.



Fix Information

When you use the LB::prime pool command, the system now flushes the queue, so server-side congestion no longer prevents the messages from being processed.

Behavior Change