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High 'LATCH: ENQUEUE HASH CHAINS' Lock Contention Causing Performance Degradation (Doc ID 780306.1)

Last updated on APRIL 10, 2019

Applies to:

Oracle Database - Enterprise Edition - Version 9.2.0.8 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Oracle Database Cloud Service - Version N/A and later
Oracle Solaris on SPARC (64-bit)
Sun Solaris SPARC (64-bit)


Symptoms

Database performance suffers and symptoms may include one or all of high system time, O/S lock contention, high Oracle waits for locks and lock contention.

Changes

Customer is using either O/S default semaphore parameters or has purposefully set semmsl (the number of semaphores per set) higher than the recommended values in the Oracle installation guides.  A typical default value seems to be 6004.

Cause

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In this Document
Symptoms
Changes
Cause
Solution
References

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