<br><br><div class="gmail_quote">On Wed, Nov 7, 2012 at 8:29 AM, Domas Monkus <span dir="ltr"><<a href="mailto:domas.monkus@canonical.com" target="_blank">domas.monkus@canonical.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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Hello,<br>
I have found the following wish-list item in the ceilometer project:<br>
<a href="https://bugs.launchpad.net/ceilometer/+bug/1010037" target="_blank">https://bugs.launchpad.net/ceilometer/+bug/1010037</a><br>
<br>
I have read the associated email thread [1] and launchpad blueprint
[2], however, the task still seems in need of further discussions.
To be more exact, there are a few things that are still unclear:<br>
<br>
1. How should pollster-specific polling intervals be specified? The
blueprint mentions that publishers (I assume it means collectors)
should specify the intervals, however I don't think that a
communication channel between the collector and the central agent
running the pollsters is in place.<br></div></blockquote><div><br></div><div>It seems like a configuration file makes the most sense. I don't know if the openstack.common.cfg module will do what we want for this, or if we should just use ConfigObj directly.</div>
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<br>
2. Should pollsters be able to specify a polling interval (perhaps
an inherited default) to the central agent?<br></div></blockquote><div><br></div><div>The pollsters shouldn't need to communicate that information to the collector or central agent.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<br>
3. If other ways of setting the polling intervals are probably
possible (e.g. the config file), should there be a hierarchy
specified of which setting override which ones?<br></div></blockquote><div><br></div><div>Having a single way to configure the setting eliminates this issue entirely, so let's just go with the configuration file.</div>
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4. Should the current
<span style="text-indent:0px;letter-spacing:normal;font-variant:normal;text-align:left;font-style:normal;display:inline!important;font-weight:normal;float:none;line-height:24px;text-transform:none;font-size:16px;white-space:normal;font-family:ff-meta-web-pro-1,ff-meta-web-pro-2,Arial,'Helvetica Neue',sans-serif;word-spacing:0px">periodic_interval configuration value be used as a
safe fall back for pollsters without</span> explicitly defined
values?<br></div></blockquote><div><br></div><div>That makes sense.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div text="#000000" bgcolor="#FFFFFF">
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5. What is the granularity of polling intervals? Seconds?<br></div></blockquote><div><br></div><div>That's how the periodic tasks work. I'm not sure if it makes sense to expose that level of granularity or not. Probably?</div>
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<br>
And finally an implementation idea:<br>
I do not think that having separate periodic tasks for each pollster
is the best solution for this problem. Assuming a second granularity
for polling intervals, the central agent manager can maintain a map
of pollsters and their intervals. As long as the manager is called
with an interval that is a GCD of its pollster intervals, it can
basically calculate how often each pollster should be queried.<br></div></blockquote><div><br></div><div>It could do that. On the other hand, the code that manages the periodic tasks is *already* doing that. Why rewrite it?</div>
<div><br></div><div>Doug</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div text="#000000" bgcolor="#FFFFFF">
<br>
Domas Monkus<br>
<br>
[1]
<a href="https://lists.launchpad.net/openstack/msg12916.html" target="_blank">https://lists.launchpad.net/openstack/msg12916.html</a><br>
[2]
<a href="https://blueprints.launchpad.net/ceilometer/+spec/publisher-counters-frequency" target="_blank">https://blueprints.launchpad.net/ceilometer/+spec/publisher-counters-frequency</a>
</div>
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