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On 03/01/11 14:00, Charles K Pepperdine wrote:
<blockquote
cite="mid:919F96FA-E09E-47BA-819C-0DFF2D9CF5F9@kodewerk.com"
type="cite"><br>
<div>...<br>
<blockquote type="cite">
<div text="#000000" bgcolor="#ffffff"> The CMS concurrent
collections are fast from what I've seen (on the order of<br>
the time between ParNew collections). The rate at which
objects are getting<br>
promoted is also low (maybe 3m per ParNew collection). CMS
thinks it<br>
can wait to start a concurrent collection. The fact that a
"promotion failure"<br>
happened makes it look like fragmentation.<br>
</div>
</blockquote>
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</div>
Even with occupancy greater than 90%? I could very well be wrong
about this but I thought that promotion failure meant just that,
the young gen collector wasn't able to stuff objects up into
tenured space. That didn't preclude fragmentation but in this
case occupancy is 90% which IIRC is well above the OMG, I can't
keep up lets trigger a parallel collection threshold.</div>
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<br>
</blockquote>
I don't see CMSInitiatingOccupancyFraction on the command line.<br>
<h4>-Xmx896m -Xss128k -XX:NewSize=384M -XX:MaxPermSize=96m
-XX:+UseParNewGC -XX:+UseConcMarkSweepGC</h4>
so CMS isn't using occupancy of the tenured gen to start a cycle.
That is the<br>
default behavior.<br>
<br>
<br>
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