Thousands of active sessions waiting on latch free in relation to 'transaction branch allocation' (Doc ID 2018260.1)

Last updated on JUNE 16, 2016

Applies to:

Oracle Database - Enterprise Edition - Version 12.1.0.1 to 12.1.0.2 [Release 12.1]
Oracle Database - Enterprise Edition - Version 11.2.0.1 to 11.2.0.4 [Release 11.2]
Information in this document applies to any platform.

Symptoms

A large number of active sessions are waiting for latch free as per the awr report which shows 

EventWaitsTime(s)Avg wait (ms) % DB timeWait Class
latch free 1,237,131 128,011 103 31.44 Other 

Most of latch waits are for "transaction branch allocation" i.e. 121,162 seconds 

Latch NameGet RequestsPct Get Miss Avg Slps /MissWait Time (s)NoWait Requests
transaction branch allocation 112,307,430 15.11 0.07 121162 0

AWR report shows the highest number of waits/sleeps are occurring in function ksupuc followed by functions ktcsbr and ktcbba as per the following section

Latch NameWhereNoWait Misses SleepsWaiter Sleeps
transaction branch allocation ksupuc 0 811,508 891,320
transaction branch allocation ktcsbr 0 128,862 82,780
transaction branch allocation ktcbba 0 84,239 143,093

Cause

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