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"SELECT SPARE6 FROM USER$ WHERE USER#=:1" Causes Blocking Sessions, Hangs on RAC on 12.2.x with Infiniband 'gc cr request'<='gc buffer busy acquire'<='library cache lock' Waits on a Single Session (Doc ID 2546022.1)

Last updated on SEPTEMBER 16, 2021

Applies to:

Oracle Database Appliance X6-2 HA Hardware - Version All Versions to All Versions [Release All Releases]
Oracle Database Appliance X5-2 - Version All Versions to All Versions [Release All Releases]
Linux x86-64

Symptoms

The two most common symptoms for this problem are:

  •  'gc cr request'<='gc buffer busy acquire'<='library cache lock'
  • "SELECT SPARE6 FROM USER$ WHERE USER#=:1"

Description and context.

After an upgrading, installing or a new RAC configuration on 12.2.x GI and/or database you encounter hangs and notable waits on previous working functionality.

 

Waits can also be identified using Hang Manager analysis or System State Dumps.

- 'gc cr request'<='gc buffer busy acquire'<='library cache lock'

Further investigation will show that the following query is related.
This query will show a Single Session hanging other sessions.

- "SELECT SPARE6 FROM USER$ WHERE USER#=:1"

Factors associated with the problem are:



Infiniband also appears to be related.
Exadata and ODA are a few of the potential configurations likely to see this problem.

 

Changes

 Changes associated with this issue

A possible additional change which might introduce the problem is: 

Note: This problem is frequently only seen after an upgrade to 12.2.x all other things being equal.

Cause

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In this Document
Symptoms
 The two most common symptoms for this problem are:
 Description and context.
 Factors associated with the problem are:
Changes
  Changes associated with this issue
Cause
Solution
 Solution and Workaround

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