Re: Controlling load

Thank you for the response.

 As i mentioned we have 48 core CPU with 2 socket each for a node, so Total ~96 core per node. And the OEM also its showing showing the red line bar on AAS as 96 as Max limit. But during three different issue period we see the below AAS shoot ups above 96 and the wait distribution,  Basically its combination of wait event from classes like concurrency, configuration and others but CPU part is minimum.

1. AAS shoot up to - 180, out of which 7% CPU and 34% (buffer busy waits), ~20% Log file switch checkpoint incomplete, 16% enq:tx allocate ITL entry, 12% Others.
2. AAS shoot up to - 515, out of which 4% CPU and 46% (library cache lock), ~17% library cache mutex, 12% enq:tx allocate ITL entry entry, 12% Others.
3. AAS shoot up to - 120, out of which 9% CPU and 30% (buffer busy waits), ~13% Log file switch checkpoint incomplete, 31% enq:tx allocate ITL entry entry, 8% BCT buffer space.

> Resource manager can help you if you are seeing resource shortage (CPU
> shortage) during these periods and CPU shortage is causing the Concurrency
> waits.
> If you are not seeing CPU shortage, then you need traditional database
> troubleshooting methods and resource manager will not help you.
> For example if you are behind in 19c patching, then for example before
> 19.15 there was bug 32898678, 33541865 (fixed in 19.17) and multiple others
> that caused block change tracking (BCT) to freeze the database or just high
> BCT buffer space waits.
>
> On Wed, Feb 22, 2023 at 6:08 AM yudhi s <learnerdatabase99_at_gmail.com>
> wrote:
>
>> Thank you Andy.
>>
>> I have never used the DB resource consumer group in our databases though.
>> But going through the doc, it seems it can be set for many number of input
>> parameters and also on many resources. Yet to test it , however In most
>> cases I see it's set on amount of cpu. So in our case will it be good idea
>> to determine the cpu percentage and define the plan or we can do it on
>> number of average active sessions which will be again hardcoded value only.
>>
>> We need to set it for multiple input program values in our case. If you
>> can pass on reference to some sample doc with its exact code
>> implementation, that would be great.
>>
>> On Wed, 22 Feb, 2023, 2:11 am Andy Sayer, <andysayer_at_gmail.com> wrote:
>>
>>> You can set up resource manager to map different programs to different
>>> resource consumer groups. You’ll need to make sure you order the priority
>>> of mapping to make sure program is checked before service name (if that’s
>>> not the default). It’s all in dbms_resource_manager
>>>
>>> Thanks,
>>> Andy
>>>
>>> On Tue, Feb 21, 2023 at 12:19 PM, yudhi s <learnerdatabase99_at_gmail.com>
>>> wrote:
>>>
>>>> Hello Listers,
>>>> On a normal day, we see sessions/AAS per ~1 minute interval as ~50 in
>>>> this database. and they are mainly from two specific 'programs' (say e.g.
>>>> prog_batch, prog_online). But during certain periods of the day we saw a
>>>> large number of sessions with programs as 'prog_batch' (i.e. with AAS>~500)
>>>> flooding the database and we are seeing large concurrency waits, bct buffer
>>>> space waits all over the database. And its impacting critical sessions of
>>>> other programs i.e. prog_online. So considering 'prog_batch' is meant for
>>>> batch kind of processes and it's okay for those sessions to queue-up and
>>>> run a few minutes longer, but at the same time we can't afford to impact
>>>> the sessions from prog_online, as those are latency sensitive online users.
>>>> But we found both of these programs are pointing to the same database
>>>> services and running on the same node-1. So , apart from controlling the
>>>> number of sessions/connections from the application end, can we do some
>>>> easy fixes with regards to the service config level, which will better
>>>> control the incoming load? Or say putting some cap on the incoming sessions
>>>> from prog_batch?
>>>> This is a 19C database with 2 node RAC and its an Exadata machine. Each
>>>> node is a 48 core, 2 socket. Both the programs were using the same service
>>>> and having preferred nodes as node-1.
>>>>
>>>> Regards
>>>> Yudhi
>>>>
>>>
>
> --
> Ilmar Kerm
>

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