Re: Oracle 12.2 logins hang

From: Chris Stephens <>
Date: Tue, 29 May 2018 12:44:16 -0500
Message-ID: <>

that's definitely not the case. we can reproduce the issue on demand and know that invalid logins are not related.

On Tue, May 29, 2018 at 11:38 AM Chris Taylor <> wrote:

> Do you have any locked accounts that are being attempted to be logged in
> to? OR, heavy attempts with invalid passwords?
> There's a known issue where sessions that bang away at locked accounts
> (or with invalid passwords) cause a basic DoS -like scenario where no users
> can login.
> You may want to turn on login audits to see if you're getting a lot of
> failed logins for a particular account.
> As far as I know this problem still exists in 12c.
> High 'library cache lock' Wait Time Due to Invalid Login Attempts (Doc ID
> 1309738.1)
> Chris
> On Tue, May 29, 2018 at 9:33 AM, Chris Stephens <>
> wrote:
>> Oracle 12.2 on CentOS 7.
>> we recently upgraded one of our databases from 12.1 to 12.2 on centos 7.
>> we have an application that logs on and logs off for every database
>> operation regardless of size. that results in an obscenely high
>> connection/disconnection rate which eventually (after several minutes)
>> results in all logins to the application account hanging indefinitely on
>> "library cache lock". there is no lock holder. the session is attempting
>> to update last logon column in sys.user$ (one of the spare columns).
>> we are working to address the application issue properly but have
>> implemented database resident connection pooling to temporarily alleviate
>> the issue. we thought that had the issue licked but it happened again on
>> Friday when connection pool was in place. we think there were several
>> sessions created outside of the pool by this account earlier in the day or
>> the day before but i can't see how that would contribute to the problem.
>> we have an SR open with Oracle and have provided systemstate and
>> hanganalyze output to them. looking at the hang analyze shows blocked
>> sessions waiting on the previously mentioned "library cache lock" but "blocking:
>> 0 sessions".
>> has anyone seen this before?
>> any suggestions on how to work around the issue until we get the
>> application code changed to reuse sessions?

Received on Tue May 29 2018 - 19:44:16 CEST

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