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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Intension is not to transfer work load of a failed engine onto an active one. Convergence implementation that we are working on will be able to recover from
a failure, provided a timeout notification hits heat-engine. All I want is a safe holding area for my timeout tasks. Timeout can be a stack timeout or a resource timeout.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">By code change
</span><span style="font-size:11.0pt;font-family:Wingdings;color:#1F497D">J</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> I meant posting to a job queue will be a matter of decorating timeout method and firing it for
a delayed execution. Felt that we need not use taskflow just for posting a delayed execution(timer in our case).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Correct me if I’m wrong.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">-Vishnu<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> Joshua Harlow [mailto:harlowja@outlook.com]
<br>
<b>Sent:</b> Thursday, November 13, 2014 2:15 PM<br>
<b>To:</b> OpenStack Development Mailing List (not for usage questions)<br>
<b>Subject:</b> Re: [openstack-dev] [Heat] Using Job Queues for timeout ops<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">A question;<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">How is using something like celery in heat vs taskflow in heat (or at least concept [1]) 'to many code change'.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Both seem like change of similar levels ;-)<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">What was your metric for determining the code change either would have (out of curiosity)?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Perhaps u should look at [2], although I'm unclear on what the desired functionality is here.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Do u want the single engine to transfer its work to another engine when it 'goes down'? If so then the jobboard model + zookeper inherently does this.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Or maybe u want something else? I'm probably confused because u seem to be asking for resource timeouts + recover from engine failure (which seems like a liveness issue and not a resource timeout one), those 2 things seem separable.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">[1] <a href="http://docs.openstack.org/developer/taskflow/jobs.html">http://docs.openstack.org/developer/taskflow/jobs.html</a><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">[2] <a href="http://docs.openstack.org/developer/taskflow/examples.html#jobboard-producer-consumer-simple">http://docs.openstack.org/developer/taskflow/examples.html#jobboard-producer-consumer-simple</a><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Nov 13, 2014, at 12:29 AM, Murugan, Visnusaran <<a href="mailto:visnusaran.murugan@hp.com">visnusaran.murugan@hp.com</a>> wrote:<o:p></o:p></p>
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<br>
<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Hi all,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Convergence-POC distributes stack operations by sending resource actions over RPC for any heat-engine to execute. Entire stack lifecycle will be controlled by worker/observer
notifications. This distributed model has its own advantages and disadvantages.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Any stack operation has a timeout and a single engine will be responsible for it. If that engine goes down, timeout is lost along with it. So a traditional way is for other
engines to recreate timeout from scratch. Also a missed resource action notification will be detected only when stack operation timeout happens.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">To overcome this, we will need the following capability:<o:p></o:p></span></p>
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<p class="MsoNormal" style="text-indent:-.25in"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">1.</span><span style="font-size:7.0pt"> <span class="apple-converted-space"> </span></span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Resource
timeout (can be used for retry)<o:p></o:p></span></p>
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<p class="MsoNormal" style="text-indent:-.25in"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">2.</span><span style="font-size:7.0pt"> <span class="apple-converted-space"> </span></span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Recover
from engine failure (loss of stack timeout, resource action notification)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Suggestion:<o:p></o:p></span></p>
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<p class="MsoNormal" style="text-indent:-.25in"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">1.</span><span style="font-size:7.0pt"> <span class="apple-converted-space"> </span></span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Use
task queue like celery to host timeouts for both stack and resource.<o:p></o:p></span></p>
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<p class="MsoNormal" style="text-indent:-.25in"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">2.</span><span style="font-size:7.0pt"> <span class="apple-converted-space"> </span></span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Poll
database for engine failures and restart timers/ retrigger resource retry (IMHO: This would be a traditional and weighs heavy)<o:p></o:p></span></p>
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<p class="MsoNormal" style="text-indent:-.25in"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">3.</span><span style="font-size:7.0pt"> <span class="apple-converted-space"> </span></span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Migrate
heat to use TaskFlow. (Too many code change)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">I am not suggesting we use Task Flow. Using celery will have very minimum code change. (decorate appropriate functions)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Your thoughts.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">-Vishnu<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">IRC: ckmvishnu<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Helvetica","sans-serif"">_______________________________________________<br>
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<a href="mailto:OpenStack-dev@lists.openstack.org"><span style="color:#954F72">OpenStack-dev@lists.openstack.org</span></a><br>
<a href="http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev"><span style="color:#954F72">http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev</span></a><o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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