Re: Oracle 12.2 logins hang

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 < christopherdtaylor1994_at_gmail.com> 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 <cstephens16_at_gmail.com>
> 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?
>>
>
>

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