Wait event: kksfbc child completion

Noticed this wait event "kksfbc child completion" in one of our database when a client complained that the report which was generally taking few seconds is hung today for more than hours!!!

When looked into the sessions, found that this session is waiting on "kksfbc child completion".

This is confirmed bug "6795880 - Session spins / OERI after 'kksfbc child completion' wait - superceded [ID 6795880.8]"

Bug Description:


This fix has been superseded by bug:8575528.

A session may go into an infinite spin just after a wait
for 'kksfbc child completion'. The spin occurs with
a stack including kksSearchChildList -> kkshgnc where
kksSearchChildList loops forever.

This problem can also lead to internal error such as any of
ORA-600 [kksSearchChildList1], ORA-600 [kksSearchChildList2]
ORA-600 [kksSearchChildList3], ORA-600 [kkshgnc-nextchild]

Or Trace dumps on kksSearchChildList4 .

Note:
  This fix is disabled by default in 10g.
  To enable this fix you must explicitly set the following
  parameter for instance startup:
    "_cursor_features_enabled" = 10

Metalinks Info on this bug:

Bug 6795880  Session spins / OERI after 'kksfbc child completion' wait - superceded

 This note gives a brief overview of bug 6795880. 
 The content was last updated on: 05-APR-2011
 Click here for details of each of the sections below.

Affects:

Product (Component)	Oracle Server (Rdbms)
Range of versions believed to be affected	Versions BELOW 11.2
Versions confirmed as being affected	11.1.0.6 10.2.0.4 10.2.0.3
Platforms affected	Generic (all / most platforms affected)

 Note that this fix can cause / expose the problem described in Bug:8575528

 Note that this fix has been superceded by the fix in Bug:8575528 

Fixed:

This issue is fixed in

11.1.0.7 (Server Patch Set) 10.2.0.5 (Server Patch Set) 10.2.0.4 Patch 5 on Windows Platforms

Symptoms:	Related To:
Hang (Process Spins) Internal Error May Occur (ORA-600) ORA-600 [kksSearchChildList1] ORA-600 [kksSearchChildList2] ORA-600 [kksSearchChildList3] ORA-600 [kkshgnc-nextchild] Dump in or under kksSearchChildList4 Waits for "cursor: pin S" Waits for "kksfbc child completion"	This fix is DISABLED by default _CURSOR_FEATURES_ENABLED