Provided, that is, that the project with the low next_rpc_delay value provides 
sufficient server resources to manage the workflow expeditiously.
 
I've been noticing recently that the SETI servers can commonly take up to 90 
seconds to respond to a routine RPC. While waiting for that reply, the client 
appears to be inhibited from initiating an RPC to another project.
 
Nobody would suggest that SETI should ever consider going low-latency, but I'm 
using the example to question whether the combination of low-latency and a 
sluggish server could lead to the sort of problems for other projects that John 
described.


>________________________________
>From: David Anderson <[email protected]>
>To: [email protected] 
>Sent: Friday, 10 August 2012, 19:43
>Subject: Re: [boinc_dev] Changes to client scheduler from 6.12.33 to 7.0.25?
>
>There's nothing wrong with a small next_rpc_delay value, e.g. 1 minute.
>This will have no effect on other projects.
>
>The semantics of this are:
>- the client issues a scheduler RPC to the project every 1 minute
>- If the project has the highest scheduling priority,
>  this RPC will include work requests for resource types
>  that are not above the max buffer limit
>  (regardless of per-resource backoff).
>
>It a project (like Patricio's) has sporadic job availability,
>then it will typically have highest scheduling priority.
>However, as it processes jobs the priority will decrease,
>so it won't block out other project.
>
>-- David
>
>On 10-Aug-2012 7:36 AM, Richard Haselgrove wrote:
>> I would hope, and expect, that if anyone set an extreme low-latency value
>> like a next_rpc_delay of 1 minute or less on a public-facing volunteer
>> project, peer pressure from other projects would rapidly force them to change
>> their mind.
>>
>> But as the front page of the website makes clear, BOINC is also designed to
>> work as a virtual campus supercomputer centre, or as a company desktop grid.
>> Under those circumstances, the risk of blocking other projects is lessened,
>> and I think BOINC should work as described in the Wiki.
>>
>>
>>> ________________________________ From: "[email protected]"
>>> <[email protected]> To: Patricio Vidal <[email protected]>
>>> Cc: [email protected]; [email protected] Sent:
>>> Friday, 10 August 2012, 15:27 Subject: Re: [boinc_dev] Changes to client
>>> scheduler from 6.12.33 to 7.0.25?
>>>
>>> There is still no point in the connection if the client is not going to
>>> ask for work from the project anyway.
>>>
>>> The observation is that it would only take a very small number of
>>> low-latency projects to starve all other projects of connections if the
>>> connection period to the server is short enough.
>>>
>>> For example, if a connection takes 15 seconds and there are 4 projects
>>> with a server specified connection period of a minute, then no other
>>> projects will ever be contacted for anything as there will always be a
>>> pending connection to a low-latency project.  If these connections only
>>> happen when the client would ask for work from the project if it were
>>> contactable, then the situation improves greatly.  It can still be the case
>>> where all 4 rise to the top of the list of projects from which the client
>>> wants work - in that case, the client will get no work from anywhere else
>>> until one of these projects has supplied work.
>>>
>>> jm7
>>>
>>>
>>> |------------> | From:      | |------------>
>>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>>
>|Patricio Vidal <[email protected]> 
>                                                                  |
>>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>>
>|------------>
>>> | To:        | |------------>
>>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>>
>|<[email protected]> 
>                                                                    |
>>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>>
>|------------>
>>> | Date:      | |------------>
>>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>>
>|08/10/2012 10:04 AM 
>                                                                  |
>>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>>
>|------------>
>>> | Subject:  | |------------>
>>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>>
>|Re: [boinc_dev] Changes to client scheduler from 6.12.33 to 7.0.25? 
>                                                                  |
>>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>>
>|------------>
>>> | Sent by:  | |------------>
>>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>>
>|<[email protected]> 
>                                                                    |
>>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>>>>
>In my previous email I meant to say ".. we can't have clients waiting
>>> hours..."
>>>
>>> I just found in the wiki that the next_rpc_delay is exactly designed for
>>> my purpose: http://boinc.berkeley.edu/trac/wiki/LowLatency#
>>>
>>> Based on the wiki it seems to me the clients should contact the server
>>> using the rpc_delay regardless they have work from the project.
>>>
>>> Patricio.
>>>
>>>
>>>
>>>
>>> yoyo <yoyo@mailueberfall .de> To Patricio Vidal 08/10/2012 01:21 AM
>>> <[email protected]> cc [email protected]
>>>
>>> Subject Re: [boinc_dev] Changes to client scheduler from 6.12.33 to
>>> 7.0.25?
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> The client doesn't wait for hours if the server has work. Even not if the
>>> workunits are very short. Before the client runs out of work it fetches
>>> new ones. Additional you can configure on the server, that the client
>>> should periodic, e.g. every hour, connect to the server. I use it and let
>>> the client connect at least every 5h. Was this next_epc_delay removed from
>>> trunc? I use the client connect to check if a workunit which is in the
>>> queue of the client can be deleted.
>>>
>>> yoyo
>>>
>>> Patricio Vidal schrieb: Yes, we need that functionality. Our jobs last from
>>> minutes to few hours so we can have the clients waiting hours to contact
>>> the server.
>>>
>>> Is there a reason why the client blocks the other projects if it has a
>>> very short request cycle and it does not have work? I would think that if
>>> it doesn't has work it should jump to the next project in the list.
>>>
>>> This functionality is critical for any project that has relative short
>>> (few hours) jobs and it needs the results back as soon as possible. I
>>> guess this usage is more typical of Boinc projects deployments in private
>>> networks.
>>>
>>> Would it make sense to add another option to the configuration file for
>>> this behavior? Something like <next_work_request_rpc_delay> ? Or just
>>> restore part of the behavior of  <next_rpc_delay> ? The old behavior has
>>> been that way for years, right? Is it a issue with other projects so that
>>> the behavior was changed?
>>>
>>> Patricio.
>>>
>>>
>>>
>>>
>>> John.McLeod@sybase. com To 08/09/2012 04:50 PM        yoyo
>>> <[email protected]> cc [email protected],
>>>
>>> [email protected], Patricio Vidal
>>> <[email protected]>
>>>
>>> Subject Re: [boinc_dev] Changes to client scheduler from 6.12.33 to
>>> 7.0.25?
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> They want the clients not to "go to sleep" for a long time if there is no
>>> work for a bit.  Trickle messages only work if there is work from that
>>> project actually on the client.
>>>
>>> There are some problems with contacting projects constantly under certain
>>> circumstances.  If there is no work on the client from the client and the
>>> client is not interested in fetching work from that project, then there is
>>> no point in a contact at all.  There would be nothing that the server
>>> could legitimately do.  In this case, it is just taking up bandwidth that
>>> some users pay for by the byte or have caps on usage.
>>>
>>> The code was modified so that no contact would be made if there was no
>>> work on the client from the project.  It could be modified so that the
>>> client would talk to the project on the period specified if it either had
>>> work from that project, or was interested in work from that project.  i.e.
>>> The queue is not full and that project was currently the top of the list
>>> for work fetch.  The problem with this is if this project has a very short
>>> request cycle and it does not have work, it will block the client from
>>> asking any other projects for work and the client would go idle as a
>>> result.
>>>
>>> jm7
>>>
>>>
>>> |------------> | From:      | |------------>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>|yoyo <[email protected]>
>>> |
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>|------------>
>>> | To:        | |------------>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>|Patricio Vidal <[email protected]>
>>> |
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>|------------>
>>> | Cc:        | |------------>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>|<[email protected]>, <[email protected]>,
>>> <[email protected]> |
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>|------------>
>>> | Date:      | |------------>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>|08/09/2012 03:37 PM
>>> |
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>|------------>
>>> | Subject:  | |------------>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>|Re: [boinc_dev] Changes to client scheduler from 6.12.33 to
>>> 7.0.25? |
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>For what reason should the client contact the server so often?
>>> You just can use trickle messages to be sent by the client.
>>>
>>> yoyo
>>>
>>> Patricio Vidal schrieb: Yes, for our project we need the clients to contact
>>> the server every few minutes. We send jobs that last from 20 minutes to few
>>> hours. If the clients don't contact the server for several hour then we are
>>> in trouble.
>>>
>>> Regards, Patricio.
>>>
>>>
>>>
>>>
>>>
>>>
>>> John.McLeod@sybase.
>>>
>>> com
>>>
>>> To 08/09/2012 11:21 AM        Patricio Vidal
>>>
>>>
>>> <[email protected]>
>>>
>>> cc
>>>
>>> [email protected],
>>>
>>>
>>> [email protected] Subject Re: [boinc_dev] Changes to
>>> client scheduler from 6.12.33 to 7.0.25?
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> It was removed in order to avoid hammering projects from clients that were
>>> not going to ask for work and had no work they were working on.
>>>
>>> Perhaps, the code could be modified slightly again.  Only ignore the
>>> setting for contact server every X if the client has no work from the
>>> server and the client would not ask for work from the project.
>>>
>>> BTW, a really short contact period will play havoc with multi project
>>> clients as they will not be able to get work from elsewhere while you have
>>> no work.
>>>
>>> jm7
>>>
>>>
>>> |------------> | From:      | |------------>
>>>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>|Patricio Vidal <[email protected]>
>>> |
>>>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>|------------>
>>> | To:        | |------------>
>>>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>|<[email protected]>
>>> |
>>>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>|------------>
>>> | Date:      | |------------>
>>>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>|08/09/2012 11:00 AM
>>> |
>>>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>|------------>
>>> | Subject:  | |------------>
>>>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>|[boinc_dev] Changes to client scheduler from 6.12.33 to
>>> 7.0.25? |
>>>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>|------------>
>>> | Sent by:  | |------------>
>>>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>|<[email protected]>
>>> |
>>>
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------------------------------------|
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>Hello,
>>>
>>> I noticed a change in the client scheduler when moving from 6.12.33 to
>>> 7.0.25: I have the <next_rpc_delay> set 180 in the config.xml.
>>>
>>> For 6.12.33 the clients contact the server even if there is no work, which
>>> is our desired behavior:
>>>
>>> 8/8/2012 11:39:09 PM | AlgoGrid | Requesting new tasks for CPU 8/8/2012
>>> 11:42:12 PM | AlgoGrid | Requesting new tasks for CPU 8/8/2012 11:45:15 PM
>>> | AlgoGrid | Requesting new tasks for CPU 8/8/2012 11:48:18 PM | AlgoGrid |
>>> Requesting new tasks for CPU
>>>
>>>
>>> For 7.0.25, when there are available task the scheduler contacts the
>>> server as expected:
>>>
>>> 8/8/2012 9:26:33 PM | AlgoGrid | Requesting new tasks for CPU 8/8/2012
>>> 9:27:10 PM | AlgoGrid | Requesting new tasks for CPU
>>>
>>> ... but when there is no tasks it starts delaying the request
>>> exponentially:
>>>
>>> 8/8/2012 9:49:45 PM | AlgoGrid | Requesting new tasks for CPU 8/8/2012
>>> 10:08:23 PM | AlgoGrid | Requesting new tasks for CPU 8/8/2012 10:32:36 PM
>>> | AlgoGrid | Requesting new tasks for CPU 8/8/2012 11:37:35 PM | AlgoGrid |
>>> Requesting new tasks for CPU 8/9/2012 2:59:13 AM | AlgoGrid | Requesting
>>> new tasks for CPU 8/9/2012 10:41:06 AM | AlgoGrid | Requesting new tasks
>>> for CPU
>>>
>>>
>>> Is there a new option to force the rpc call even if there is no tasks
>>> available? We need this behavior because our boinc project needs a quick
>>> response from the clients when we schedule a job (we have workunits of
>>> about 1 min processing time and we schedule thousands at a time).
>>>
>>> Thank you, Patricio.
>>>
>>>
>>> The server  made the following annotations
>>>
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>>>
>>>
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>>>
>>>
>>>
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