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Oracle Database 12.2(Windows) connection slow down (Doc ID 2699660.1)

Last updated on SEPTEMBER 02, 2020

Applies to:

Oracle Net Services - Version to [Release 12.2]
Microsoft Windows x64 (64-bit)


Environments with a large number of new connections and disconnections through the listener will dedicated server connection delays after 1-2 weeks.

It is possible to connect in 1-2 seconds immediately after starting the instance, but it has been confirmed that the average connection time becomes 3-6 seconds when a problem starts to occur.

Not all connections slow down when a problem occurs, but in high connection demand situations, most connections are delayed and, on average, connection times are long.

Once problem occurs restarting the instance or listener will not resolve the delay.



Reproduction environment confirmed is as follows.
This problem has been confirmed in both RAC and single instance.

Database : Oracle Database 12.2
Platform : Windows Server 2016


The symptom is closely related to the amount of or the frequency of connecttion and disconnection.

Reproduction result using a program that connects/disconnects serially.

    1 days   3 days   5 days   7 days
connect/disconnect(1 hour avg)    993 877 767 706
Connection time (avg) 1.3 s 1.5 s 1.8 s 2.0 s

This result shows that the number of connections that can be connected per unit time is small due to lack of environmental resources, and the tendency of delay gradually appears.


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