Bug ID 688942: ICAP: Chunk parser performs poorly with very large chunk

Last Modified: Oct 06, 2020

Bug Tracker

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

Known Affected Versions:
12.1.0, 12.1.0 HF1, 12.1.0 HF2, 12.1.1, 12.1.1 HF1, 12.1.1 HF2, 12.1.2, 12.1.2 HF1, 12.1.2 HF2, 12.1.3, 12.1.3.1, 12.1.3.2, 12.1.3.3, 12.1.3.4, 12.1.3.5, 13.0.0, 13.0.0 HF1, 13.0.0 HF2, 13.0.0 HF3, 13.0.1, 13.1.0, 13.1.0.1, 13.1.0.2, 13.1.0.3, 13.1.0.4, 13.1.0.5, 13.1.0.6, 13.1.0.7, 13.1.0.8, 13.1.1

Fixed In:
14.0.0, 13.1.1.2, 12.1.3.6

Opened: Oct 16, 2017
Severity: 3-Major
Related AskF5 Article:
K82601533

Symptoms

When an ICAP response contains a very large chunk (MB-GB), the BIG-IP system buffers the entire chunk and reevaluates the amount of data received as each new packet arrives.

Impact

The BIG-IP system uses memory to buffer the entire chunk. In extreme cases the parser can peg the CPU utilization at 100% as long as packets are arriving.

Conditions

ICAP server returns large payload entirely in a single chunk, or otherwise generates very large chunks (MB to GB range).

Workaround

If possible, configure the ICAP server to chunk the response payload in mulitple normal sized chunks (up to a few tens of KB).

Fix Information

When an ICAP response contains a very large chunk (MB-GB), the BIG-IP system streams content back to the HTTP client or server as it arrives, without undue memory use or performance impact.

Behavior Change