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Excessive "reliable Message" waits seen on RAC after a few days uptime (Doc ID 1990796.1)

Last updated on DECEMBER 10, 2023

Applies to:

Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Oracle Database - Enterprise Edition - Version 12.1.0.2 to 12.1.0.2 [Release 12.1]
Information in this document applies to any platform.
"reliable message" waits can exceed 1 second.
This is for a 12.1.0.2 database (non-pluggable).
The problem does not manifest until a few days of up-time
The only workaround is to restart the instance.

Symptoms

Performance is affected severely for example a truncate command can take 20 minutes or more and AWR reports show high wait time for "reliable message".  

 

A hang analyze will also show 

service name: SYS$BACKGROUND 
     Current Wait Stack: 
      1: waiting for 'CSS group membership query' 

CSS group membership query's are not processed fast enough because of congestion. 

Cause

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