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<p class="MsoNormal">Folks,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’ve been trying to tackle the measurement of an irregular statistic on an embedded platform: embedded JVM garbage collection. During any given “interval” for collectd, I may have no GC activity or I might have a dozen instances where the
JVM performed garbage collection. I have a file wherein the GC numbers are stored (time of occurrence, JVM heap before, JVM heap after, time required to garbage-collect), so I can write a read plugin to simply read the file. It should be easy enough to keep
track of the last time it ran, so I can know exactly when/where to index in that file so I can start the file read at the right point (and read to the end). But the fact that I may have multiple values in any one interval is throwing me off.
<o:p></o:p></p>
<p class="MsoNormal"><br>
So if I have a set of N data points (including timestamp), can I simply iterate through a list, calling plugin_dispatch_values( &vl ) where I’ve not only set up the “standard” vl data elements but also the vl.time element also, with the appropriate timestamp?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">E.G. (very psedocode-ish) :<o:p></o:p></p>
<p class="MsoNormal">// Iterate through the N values for heap during this interval<o:p></o:p></p>
<p class="MsoNormal">for iter=0; iter<N; iter++<o:p></o:p></p>
<p class="MsoNormal">{<o:p></o:p></p>
<p class="MsoNormal"> gcdata = dataArray[iter];<o:p></o:p></p>
<p class="MsoNormal"> vl.values = gcdata.heap;<o:p></o:p></p>
<p class="MsoNormal"> vl.time = gcdata.timestamp;<o:p></o:p></p>
<p class="MsoNormal"> sstrncpy( … host, plugin, type, type_instance, etc ...);<o:p></o:p></p>
<p class="MsoNormal"> plugin_dispatch_values(&vl);<o:p></o:p></p>
<p class="MsoNormal">}<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Other obvious alternatives would be (1) to write the plugin so it would average all values of interest and just report ONE set of data (and perhaps a metric for the number of GCs that occurred during that interval); or (2) to only report
the most RECENT set of data, or (3) to have the read plugin interval much shorter than how fast I expect the GC to run. But if it’s possible, I’d rather get all of the instances recorded. Have any folks had to deal with such irregular values before?
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Dave <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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