Re: Library lock issue

Hi Lok,

First step would be to see what the library lock was against. Since 12.1, this information is easily accessed in v$db_object_cache : select * from v$db_object_cache where addr = to_char(30836511936,lpad('0X',16,'0'));
(I can't remember off the top of my head if you need to lpad to 16 characters or 18 so try 18 if this one doesn't return anything. This is all in memory so it won't work after a restart and you will need to be instance sensitive for RAC)
Then some further information about the calls that are requiring this library lock:
select sql_id, plsql_entry_object_id, plsql_entry_subprogram_id, plsql_object_id, plsql_subprogram_id
,time_model
, count(*)
from v$active_session_history
where event='library cache load lock'
group by sql_id, plsql_entry_object_id, plsql_entry_subprogram_id, plsql_object_id, plsql_subprogram_id
  ,time_model
order by count(*) desc fetch first 10 rows only;

There might be something obvious based on these results.

Thanks,
Andrew

On Wed, 12 May 2021 at 18:43, Lok P <loknath.73_at_gmail.com> wrote:

> This is version 19.9.0.0.0 Oracle version and it's an Exadata machine. We
> are seeing high wait events of "library cache load locks" on this database
> during a high activity period. Below attached is the ASH report from the
> specific period. Want to understand if this version has any bugs around
> this ?
>
> I see one bug as below related to "library cache load lock" but I am not
> seeing such parallel maintenance operations in our case though we have many
> DMLs involved with partition tables during this window. So it does not
> fully match our symptoms.
>
> High Library Cache Lock and Library Cache Load Lock Waits During
> Concurrent Heavy Mixed PMOPs and DML on Several Partitioned Tables (Doc
> ID 2181034.1)
>
>
> Regards
> Lok
>

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