<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div>A question;</div><div><br></div><div>How is using something like celery in heat vs taskflow in heat (or at least concept [1]) 'to many code change'.</div><div><br></div><div>Both seem like change of similar levels ;-)</div><div><br></div><div>What was your metric for determining the code change either would have (out of curiosity)?</div><div><br></div><div>Perhaps u should look at [2], although I'm unclear on what the desired functionality is here.</div><div><br></div><div>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.</div><div><br></div><div>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.</div><div><br></div><div>[1] <a href="http://docs.openstack.org/developer/taskflow/jobs.html">http://docs.openstack.org/developer/taskflow/jobs.html</a></div><div><br></div><div>[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></div><div><br></div><div><div>On Nov 13, 2014, at 12:29 AM, Murugan, Visnusaran <<a href="mailto:visnusaran.murugan@hp.com">visnusaran.murugan@hp.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div lang="EN-US" link="#0563C1" vlink="#954F72" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div class="WordSection1" style="page: WordSection1;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">Hi all,<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; 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></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; 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></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">To overcome this, we will need the following capability:<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in;"><span>1.<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';"> <span class="Apple-converted-space"> </span></span></span>Resource timeout (can be used for retry)<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in;"><span>2.<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';"> <span class="Apple-converted-space"> </span></span></span>Recover from engine failure (loss of stack timeout, resource action notification)<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">Suggestion:<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in;"><span>1.<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';"> <span class="Apple-converted-space"> </span></span></span>Use task queue like celery to host timeouts for both stack and resource.<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in;"><span>2.<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';"> <span class="Apple-converted-space"> </span></span></span>Poll database for engine failures and restart timers/ retrigger resource retry (IMHO: This would be a traditional and weighs heavy)<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in;"><span>3.<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';"> <span class="Apple-converted-space"> </span></span></span>Migrate heat to use TaskFlow. (Too many code change)<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; 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></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">Your thoughts.<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">-Vishnu<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">IRC: ckmvishnu<o:p></o:p></div></div>_______________________________________________<br>OpenStack-dev mailing list<br><a href="mailto:OpenStack-dev@lists.openstack.org" style="color: rgb(149, 79, 114); text-decoration: underline;">OpenStack-dev@lists.openstack.org</a><br><a href="http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev" style="color: rgb(149, 79, 114); text-decoration: underline;">http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev</a></div></blockquote></div><br></body></html>