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rep agent executor thread and exec_cmds_per_timeslice

6 posts in General Discussion Last posting was on 2012-08-23 05:00:44.0Z
vtpcnk Posted on 2012-08-14 04:09:04.0Z
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From: vtpcnk
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Subject: rep agent executor thread and exec_cmds_per_timeslice
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what exactly does the rep agent executor thread do? what is
its functional scope?

the exec_cmds_per_timeslice specifies the number of ltl
commands that the rep agent executor thread can process
before yielding cpu to other threads.

there is a note in the manual that if the inbound queue
processing is slow, increasing the value of this parameter
might bring benefits.

can somebody explain how?


Manish Negandhi [TeamSybase] Posted on 2012-08-19 16:57:42.0Z
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<vtpcnk> wrote in message news:5029cf5d.4b9e.1681692777@sybase.com...
> what exactly does the rep agent executor thread do? what is
> its functional scope?
>
> the exec_cmds_per_timeslice specifies the number of ltl
> commands that the rep agent executor thread can process
> before yielding cpu to other threads.
>
> there is a note in the manual that if the inbound queue
> processing is slow, increasing the value of this parameter
> might bring benefits.
>
> can somebody explain how?

You may want to go through this white paper to understand how this parameter
works. Note that RS has got many such parameters which might work well in
some situation
and might not benefit if workload differs therefore it is important to
understand workload and perform testing. This paper also discusses about the
testing executed

Here is summary of this parameter ..

On the other hand, the exec_cmds_per_timeslice is a bit more difficult. As
mentioned earlier, the parsing and
normalization process can be CPU intensive. As a result, since it may always
have work to do in a high volume
situation, it may be robbing CPU time from the DIST or DSI threads.
Consequently, if it should appear that data is
backing up in the inbound queue and all applicable SQT tuning (below) has
been performed, or if the DSI connections
show a lot of "awaiting command" at the replicate (taking into account the
dsi_serialization_method as discussed in the
section on Parallel DSI), you may want to lower this number. On the other
hand, if the Replication Agent is getting
behind (a much more normal problem), you may want to raise
exec_cmds_per_timeslice.

whitepaper :-
http://www.sybase.com/files/White_Papers/Sybase_RepServer_Performance_Tuning_wp_022708.pdf

-HTH
Manish Negandhi
[TeamSybase]


vtpcnk Posted on 2012-08-21 03:49:22.0Z
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Subject: Re: rep agent executor thread and exec_cmds_per_timeslice
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thanks for the response.

> Consequently, if it should appear that data is
> backing up in the inbound queue and all applicable SQT
> tuning (below) has been performed, or if the DSI
> connections show a lot of "awaiting command" at the
> replicate (taking into account the
> dsi_serialization_method as discussed in the section on
> Parallel DSI), you may want to lower this number.

but isn't it saying the exact opposite to what i mentioned
from the manual with regards data getting backed up in the
inbound queue?

>On the
> other hand, if the Replication Agent is getting
> behind (a much more normal problem), you may want to raise
> exec_cmds_per_timeslice.
>

i wonder if the utility of this parameter is as simple as
getting more ltl commands into the inbound queue, so that
the commits will be encountered faster, which will cause the
data to move from the inbound to the outbound queue.


vtpcnk Posted on 2012-08-21 03:53:31.0Z
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> whitepaper :-
>

http://www.sybase.com/files/White_Papers/Sybase_RepServer_Performance_Tuning_wp_022708.pdf

is it possible to get a text version of this white paper?


Manish Negandhi [TeamSybase] Posted on 2012-08-21 14:59:22.0Z
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<vtpcnk> wrote in message news:5033063a.2b82.1681692777@sybase.com...
>> whitepaper :-
>>
> http://www.sybase.com/files/White_Papers/Sybase_RepServer_Performance_Tuning_wp_022708.pdf
>
> is it possible to get a text version of this white paper?

Try google books :-)

http://books.google.co.in/books?id=9XA40gBwbfYC&pg=PA351&lpg=PA351&dq=Sybase+RepServer+Performance+Tuning&source=bl&ots=A6VRDLqGX0&sig=iIp168J07oKsurAGUYFfxZF-k90&hl=en&sa=X&ei=E6IzUNfXCYfrrQeHkYHoAw&redir_esc=y#v=onepage&q=Sybase%20RepServer%20Performance%20Tuning&f=false

Manish Negandhi
[TeamSybase]


vtpcnk Posted on 2012-08-23 05:00:44.0Z
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> Try google books :-)
>
> http://books.google.co.in/books?

hey thanks for that reference.

btw any ideas about the relationship between
exec_cmds_per_timeslice and scan batch size?

would it be right to take it that scan batch size relates
more to the part of the process which extracts the data from
the transaction log, while exec_cmds_per_timeslice relates
more to the deposit of the data to the inbound queue?

scan batch size talks of 'log records' while 'exec_cmd ...'
refers to ltl. default for scan batch size is 1000, while
for exec_cmd_per_timeslice it is 5.

and does one affect the other? ie should both be configured
taking into account the size of the other?

though both are related to the rep agent, it is interesting
to note that 'exec_cmds_per_timeslice' is configured through
the connection.

appreciate the insights.