Re: Odd wait event freezing database

You may want to consider this MOS Note and see if it applies.

I have run into this recently on 11.2.0.4 RAC, though it is not Exadata.

*Very High Waits for 'reliable message' After Upgrade to 11.2.0.4 When Using Result Cache (Doc ID 1951729.1)*
Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist Principal Consultant at Pythian
Oracle ACE Alumni
Pythian Blog http://www.pythian.com/blog/author/still/ Github: https://github.com/jkstill

On Thu, Apr 8, 2021 at 11:29 AM Lok P <loknath.73_at_gmail.com> wrote:

> Hi All, Its version 11.2.0.4 of Oracle exadata is a 4 node RAC database.
> We are seeing one of the query runs normally finish in a few seconds but
> sometimes it runs for 3-4 minutes with the wait event being noted as
> "reliable message" and during that time period things seem to freeze in the
> database almost all the nodes getting stuck. So I am not sure if this query
> is the cause of the slowness or the victim, but it seems whenever such an
> issue occurred this query was getting executed from multiple sessions and
> was running longer than expected time. No change in plan happened for this
> query and with the same plan it used to finish in seconds during other
> times. So wanted to understand if we are hitting any bug around this wait
> event as this looks a bit unusual? It seems happening while scanning mostly
> table TSFS in FULL , want to understand what's wrong with scanning table
> TSFS?
> Below attached is the sql monitor for the same query which is showing all
> time(~200+ seconds) being spent on event "reliable message" only.
>
>
>

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