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<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Hi Rajul,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">For the `agent idea`, I think it is very good.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">However, in OpenStack, that idea may be really hard for us.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">The reason is the same with what Boris think.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">For the sampling part, head-based sampling can be implemented in OSprofiler.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">For tail-based and adaptive sampling, it is another story.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">However, in naïve way, we can use sampling abilities from other OpenTracing compatible tracers<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">such as Uber Jaeger, Appdash, Zipkin (has an open pull request), LighStep … by making OSprofiler<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">compatible with OpenTracing API.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">ICYMI, Boris is father of OSprofiler in OpenStack [1]<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">[1] https://specs.openstack.org/openstack/oslo-specs/specs/mitaka/osprofiler-cross-service-project-profiling.html<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Vinh Nguyen Trong<i><o:p></o:p></i></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">PODC – Fujitsu Vietnam Ltd.</span><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;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"> Rajul Kumar [mailto:kumar.raju@husky.neu.edu]
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<b>Sent:</b> Friday, 04 August, 2017 03:49<br>
<b>To:</b> OpenStack Development Mailing List (not for usage questions) <openstack-dev@lists.openstack.org><br>
<b>Subject:</b> Re: [openstack-dev] [oslo][performance] Proposing tail-based sampling in OSProfiler<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">Hi Boris<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">That is a point of concern. <o:p></o:p></p>
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<p class="MsoNormal">Can you please direct to any of those?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Anyways, we don't have anything in place for OpenStack yet.<o:p></o:p></p>
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<p class="MsoNormal">Now, either we pick another tracing solution like Zipkin, Jaeger etc. which have their own limitations OR enhance OSProfiler.<o:p></o:p></p>
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<p class="MsoNormal">We pick the later as it's most native and better coupled with OpenStack as of now. <o:p></o:p></p>
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<p class="MsoNormal">I understand that we may be blocked by these issues. However, I feel it'll be better to fight with OSProfiler than anything else till we come up with something better :)<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thanks<o:p></o:p></p>
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<p class="MsoNormal">Rajul<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><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 Thu, Aug 3, 2017 at 4:01 PM, Boris Pavlovic <<a href="mailto:boris@pavlovic.me" target="_blank">boris@pavlovic.me</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Rajul, <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">May I ask why you think so? <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Exposed by OSprofiler issues are going to be really hard to fix in current OpenStack architecture. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Best regards,<o:p></o:p></p>
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<p class="MsoNormal">Boris Pavlovic <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 Thu, Aug 3, 2017 at 12:56 PM, Rajul Kumar <<a href="mailto:kumar.raju@husky.neu.edu" target="_blank">kumar.raju@husky.neu.edu</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Hi Boris<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Good to hear from you.<o:p></o:p></p>
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<p class="MsoNormal">May I ask why you think so? <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">We do see some potential with OSProfiler for this and further objectives.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thanks<o:p></o:p></p>
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<p class="MsoNormal"><span style="color:#888888">Rajul<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">On Thu, Aug 3, 2017 at 3:48 PM, Boris Pavlovic <<a href="mailto:boris@pavlovic.me" target="_blank">boris@pavlovic.me</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Rajul, <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">It makes sense! However, maybe it's a bit too late... ;) <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Best regards,<o:p></o:p></p>
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<p class="MsoNormal">Boris Pavlovic <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 Thu, Aug 3, 2017 at 12:16 PM, Rajul Kumar <<a href="mailto:kumar.raju@husky.neu.edu" target="_blank">kumar.raju@husky.neu.edu</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Hello everyone<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I have added a blueprint on having tail-based sampling as a sampling option for continuous tracing in OSProfiler. It would be really helpful to have some thoughts, ideas, comments on this from the community.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Continuous tracing provides a good insight on how various transactions behave across in a distributed system. Currently, OpenStack doesn't have a defined solution for continuous tracing. Though, it has OSProfiler that does generates selective
traces, it may not capture the occurrence. Even if we have OSProfiler running continuously [1], we need to sample the traces so as to cut down the data generated and still keep the useful info.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Head based sampling can be applied that decides initially whether a trace should be saved or not. However, it may miss out on some useful traces. I propose to have tail-based sampling [2] mechanism that makes the decision at the end of
the transaction and tends to keep all the useful traces. This may require a lot of changes depending on what all type of info is required and the solution that we pick to implement it [2]. This may not affect the current working of any of the services on OpenStack
as it will be off the critical path [3]. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Please share your thoughts on this and what solution should be preferred in a broader OpenStack's perspective.<o:p></o:p></p>
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<p class="MsoNormal">This is a step in the process of having an automated diagnostic solution for OpenStack cluster.<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="https://blueprints.launchpad.net/osprofiler/+spec/osprofiler-overhead-control" target="_blank">https://blueprints.launchpad.net/osprofiler/+spec/osprofiler-overhead-control</a><o:p></o:p></p>
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<p class="MsoNormal">[2] <a href="https://blueprints.launchpad.net/osprofiler/+spec/tail-based-coherent-sampling" target="_blank">https://blueprints.launchpad.net/osprofiler/+spec/tail-based-coherent-sampling</a><o:p></o:p></p>
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<p class="MsoNormal">[3] <a href="https://blueprints.launchpad.net/osprofiler/+spec/asynchronous-trace-collection" target="_blank">https://blueprints.launchpad.net/osprofiler/+spec/asynchronous-trace-collection</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">Thanks<o:p></o:p></p>
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<p class="MsoNormal"><span style="color:#888888">Rajul Kumar<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="color:#888888"><o:p> </o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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