Database hangs while sessions waiting for 'gc freelist'
(Doc ID 2073798.1)
Last updated on DECEMBER 30, 2020
Applies to:Oracle Database - Enterprise Edition - Version 18.104.22.168 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.
Frequently a database was getting hung. We noticed that many sessions were waiting for 'gc freelist', this wait event means that the sessions are waiting to get 'Lock Elements' (LE).
Also we may see DRM executing a pseudo-reconfiguration like:
note that the reason for the pseudo-reconfiguration was to free LE (Lock Elements).
Possibly _gc_element_percent was already set to 140, which increases the number of LEs created, but may not help to prevent the issue.
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