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Tony,<br>
<br>
As you have seen at the jconsole-screenshot the app does make very
few garbage. It is optimized to make no garbage. But suddenly there
seems to be every 90 seconds about 4 gb of (new) garbage (even the
load of the app does not change). Therefore I thought it might be
the g1-collector. I will try to reproduce this senario an have a
closure look on it.<br>
<br>
Flo<br>
<br>
Am 12.12.2011 15:46, schrieb Tony Printezis:
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Florian,<br>
<br>
Not sure what you mean by "the same GC". It is because the space
transition looks like: 16394M->12914M(20480M)? This is normal.
Heap occupancy reaches 16394M, GC happens, heap occupancy goes
down to 12914M. Next time it happens, the heap will have new
objects. This is how GCs work.<br>
<br>
Tony<br>
<br>
On 12/09/2011 09:08 PM, Florian Binder wrote:
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In the gc log it seems that there is always running the same
garbage collection.<br>
For example:<br>
$ zcat out_err.log.gz | grep 20480M | tail<br>
2011-11-28T19:13:19.482+0100: [GC cleanup
14515M->14515M(20480M), 0.1370060 secs]<br>
[ 16394M->12914M(20480M)]<br>
[ 16394M->12914M(20480M)]<br>
2011-11-28T19:17:12.509+0100: [GC cleanup
15582M->15582M(20480M), 0.1387230 secs]<br>
[ 16394M->12914M(20480M)]<br>
[ 16394M->12914M(20480M)]<br>
[ 16394M->12914M(20480M)]<br>
2011-11-28T19:21:06.089+0100: [GC cleanup
12978M->12978M(20480M), 0.1344170 secs]<br>
[ 16394M->12914M(20480M)]<br>
[ 16394M->12914M(20480M)]<br>
<br>
Therefore I assume this might be a bug ;-)<br>
You can download the whole log at: <a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="http://java4.info/g1/out_err.log.gz">http://java4.info/g1/out_err.log.gz</a><br>
<br>
I don't think that we still have the logs of that very long gc,
but I will have a look for it at monday.<br>
Furthermore I do not think that we have logged there much
details of the gc. But I know that this happend on a very
special server, which contains more the 30gb of references (yes,
just references to other objects). If we run it with
CompressedOops we reduce the memory useage to nearly 50%.<br>
<br>
Flo<br>
<br>
<br>
<br>
Am 10.12.2011 01:34, schrieb Srinivas Ramakrishna:
<blockquote
cite="mid:CABzyjynoUfeND2NPoFCeDONcq9=yX1XwUVzzhuO0BZX_Rt=fcw@mail.gmail.com"
type="cite"><br>
<br>
A couple of things caught my eye....<br>
<br>
<div class="gmail_quote">
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<div> On 12/05/2011 02:19 PM, Florian Binder wrote:<br>
>> I assume you know when the data will be dropped
and reinitialized,<br>
>> right? Can you do a Full GC (with System.gc())
after you re-initialize<br>
>> the heap. This typically helps a lot with CMS.<br>
> Yes, this is exactly what we are trying at this
time ;-)<br>
> Either this Full-GC pauses are very long (60-300
seconds) they are much<br>
> shorter than after a CMS-failure (when they take
sometimes more than<br>
> 4000 seconds ;-)) and we can define when they
occure.<br>
</div>
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<div><br>
A full GC that takes an hour is definitely a bug. Have you
logged that bug?<br>
Or at least share the GC log? What's the version of the
JDK that this behaviour<br>
was seen with?<br>
<br>
</div>
<div>... <br>
</div>
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0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div> > Furthermore this should not increase the
total-heap-space:<br>
> <a moz-do-not-send="true"
href="http://java4.info/g1/all.png" target="_blank">http://java4.info/g1/all.png</a><br>
</div>
</blockquote>
<div><br>
Remember that jconsole asynchronously samples the heap,
whose size is<br>
read "with possible glitches". Rather, you should probably
rely on the GC log in order to assess<br>
the heap size after each GC event, rather than the
asynchronous samples from<br>
jconsole. I myself have not had the chance to look at yr
GC logs to see<br>
what that indicated wrt the size of Eden and of the Heap.<br>
<br>
-- ramki<br>
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<br>
<br>
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