Re: Wait: Reliable message P1: Channel context
- From: Mladen Gogala <gogala.mladen@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Sun, 14 May 2023 22:08:48 -0400
On 5/14/23 21:12, Jack van Zanen wrote:
Hi All
I am trying to find out what the wait
Reliable message with P1 channel context is. I have tried google but
no dice
One of my sessions seem to encounter it a fair bit
Oracle 12.2.01
Thank you
Jack van Zanen
Hi Jack!
That is normally an idle message saying that one process is waiting on
an IPC message from another. However, there are some bugs:
_Bug 32382667 High Reliable Message Wait From 8-Node RAC Database
at ADB_
This note gives a brief overview of bug 32382667.
The content was last updated on: 27-MAR-2023
/Click here
<
https://support.oracle.com/epmos/faces/DocumentDisplay?parent=DOCUMENT&sourceId=32382667.8&id=245840.1>
for details of each of the sections below./
_Affects:_
*Product (/Component/)* Oracle Server (Rdbms)
*Range of versions /believed/ to be affected* Versions BELOW 21.3
*Versions /confirmed/ as being affected*
* 19.16.0
<
https://support.oracle.com/epmos/faces/DocumentDisplay?parent=DOCUMENT&sourceId=32382667.8&id=245840.1#AFFECTS_19.16>
* 19.5.0
<
https://support.oracle.com/epmos/faces/DocumentDisplay?parent=DOCUMENT&sourceId=32382667.8&id=245840.1#AFFECTS_19.5>
*Platforms affected* Generic (all / most platforms affected)
_Fixed:_
So, your recourse is simple: upgrade to 21.3 or newer. Preferably, you
should upgrade to 23c, as that is the next long term support version.
Oh, by the way, the "free version for developers" is what used to be
know as XE. You can't exceed 12 GB and relink command doesn't work,
which means that you cannot patch it.
Other than that, there is a parameter regulating the size of of the
reliable message:
SQLcl: Release 23.1 Production on Sun May 14 22:01:35 2023
Copyright (c) 1982, 2023, Oracle. All rights reserved.
Last Successful login time: Sun May 14 2023 22:01:36 -04:00
Connected to:
Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.18.0.0.0
SQL> show parameter message
NAME TYPE VALUE
------------------------------- ------- -----
parallel_execution_message_size integer 16384
The smaller the message size is, the more message packets you need. You
can bump up the message size to 64K (65536) and you will presumably need
fewer of them. That will not fix the bug, after all we all know how
solid Oracle bugs are, but will make the message a bit less frequent.
Here is the manual for the parameter:
PARALLEL_EXECUTION_MESSAGE_SIZE
|PARALLEL_EXECUTION_MESSAGE_SIZE| specifies the size of messages used
for parallel execution (formerly referred to as parallel query, PDML,
Parallel Recovery, replication).
Property Description
Parameter type
Integer
Default value
Operating system-dependent
Modifiable
No
Modifiable in a PDB
No
Range of values
Minimum: 2148
Maximum: 65536, but some operating systems may have a smaller value
Basic
No
Oracle RAC
Multiple instances must have the same value.
On most platforms, the default value is as follows:
*
|16384| bytes if |COMPATIBLE| is set to |11.2.0| or higher
*
|2148| bytes if |COMPATIBLE| is less than |11.2.0|
The default value is adequate for most applications. Larger values
require a larger shared pool. Larger values result in better performance
at the cost of higher memory use. For this reason, replication gets no
benefit from increasing the size.
Regards
--
Mladen Gogala
Database Consultant
Tel: (347) 321-1217
https://dbwhisperer.wordpress.com
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