From MOS

Alert Log Messages Online Index (re)build Cleanup Appearing Repeatedly (Doc ID 2088016.1)

In this Document
Symptoms
Changes
Cause
Solution

APPLIES TO:

Oracle Database - Enterprise Edition - Version 12.1.0.2 and later
Information in this document applies to any platform.
SYMPTOMS

On 12.1.0.2, alert log contains below messages repeatedly.

online index (re)build cleanup: objn=1082690 maxretry=2000 forever=0
CHANGES

No Changes .

CAUSE

SMON is attempting to cleanup the index repeatedly.

SOLUTION

This is an SMON standard process that runs periodically. SMON is attempting to clean up the index repeatedly.

Index needs to be dropped and recreated .

For example :

DROP INDEX ix_emp_01 ;

CREATE INDEX ix_emp_01 ON emp(ename)
TABLESPACE users
STORAGE (INITIAL 20K
NEXT 20k
PCTINCREASE 75);

Rebuilding the index could also help :
ALTER INDEX ix_emp_01 REBUILD ONLINE;