<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Hi Thomas,</div><div><br></div><div>Don't mean to jump in the middle of your discussion with Bengt ...</div><div><br></div><div>Since this is M5, have you tried setting the FX Solaris CPU scheduler, (based on the hypothesis this may be thread scheduling related)?</div><div><br></div><div>hths,</div><div><br></div><div>Charlie</div><div><br></div><div><br></div><div><br>Sent from my iPhone</div><div><br>On Oct 2, 2014, at 5:35 AM, Thomas Viessmann <<a href="mailto:thomas.viessmann@oracle.com">thomas.viessmann@oracle.com</a>> wrote:<br><br></div><blockquote type="cite"><div>
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<tt>Hi Bengt,</tt><tt><br>
</tt><tt><br>
</tt><tt>Better late than never </tt><tt><span class="moz-smiley-s1"><span> :-) </span></span></tt><tt>.</tt><tt><br>
</tt><tt>There are 2200 threads, about 10% are runnable.</tt><tt><br>
</tt><tt>The application is the only one running on this M5.</tt><tt><br>
</tt><tt><br>
</tt><tt>We observe this effect quite often with G1. Relatively
short</tt><tt><br>
</tt><tt>GC times and long application thread stop times.</tt><tt><br>
</tt><tt>Interestingly I</tt><tt>'ve never seen this with CMS. But</tt><tt><br>
</tt><tt>CMS is not an option here due to fragmentation.</tt><tt><br>
</tt><tt><br>
</tt><tt>Thanks and Regards</tt><tt><br>
</tt><tt><br>
</tt><tt>Thomas </tt><tt><br>
</tt><br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 10/02/14 11:15, Bengt Rutisson
wrote:<br>
</div>
<blockquote cite="mid:542D17BE.9050104@oracle.com" type="cite">
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<br>
Hi Thomas,<br>
<br>
A very late reply. I happened to find this in my inbox and have
some comments.<br>
<br>
<div class="moz-cite-prefix">On 2014-08-29 14:15, Thomas Viessmann
wrote:<br>
</div>
<blockquote cite="mid:54006ED6.7050006@oracle.com" type="cite">
<meta http-equiv="content-type" content="text/html;
charset=windows-1252">
Hi all,<br>
<br>
<br>
I suspect a bug in G1 logging. Before I file a (possibly
incorrect) bug I would like to ask here.<br>
Is my understanding correct that the stw evacuation phase starts
at <tt><font color="#ff0000"><b>48448.931</b></font></tt> and
ends at <tt><b><font color="#ff0000">48454</font></b><b><font color="#ff0000">.034</font></b></tt> ?<br>
This would mean a stop time of 5.103 s, which is clearly a
mismatch to the reported <b><small><font color="#ff0000">9.3426141</font></small></b>
s<br>
If the stw phase in fact started at a later time e.g. at <tt><b><font color="#ff0000">48449.288 </font></b></tt>then the stop
pause would have been even shorter.<br>
<br>
In addition I do not understand how all the relatively short
evacuation phases sum up to several seconds.<br>
If I add all the MAX values <b><font color="#00cccc"><tt>69.1 +
</tt><tt>22.2</tt> + <tt>45</tt><tt> + 150.8 + </tt><tt>0.1</tt>
+ <tt>155.1</tt> + <tt>0.9 + </tt><tt>0.5</tt></font></b><small>
<b><font color="#00cccc">= 443.7</font></b><b><font color="#00cccc">ms</font></b></small><br>
<br>
<br>
<br>
<tt><br>
</tt><tt>48443.380: Total time for which application threads
were stopped: 0.0084701 seconds</tt><tt><br>
</tt><tt><font color="#ff0000"><b>48448.931</b></font>: [GC
pause (mixed) 48448.931: [G1Ergonomics (CSet Construction)
start choosing CSet, _pending_cards: 89458, predicted base
time: 73.58 ms, remaining time: 176.42 ms, target pause time:
250.00 ms]</tt><tt><br>
</tt><tt> 48448.931: [G1Ergonomics (CSet Construction) add young
regions to CSet, eden: 33 regions, survivors: 5 regions,
predicted young region time: 35.73 ms]</tt><tt><br>
</tt><tt> 48448.933: [G1Ergonomics (CSet Construction) finish
adding old regions to CSet, reason: reclaimable percentage not
over threshold, old: 19 regions, max: 77 regions, reclaimable:
2570649712 bytes (9.98 %), threshold: 10.00 %]</tt><tt><br>
</tt><tt> 48448.933: [G1Ergonomics (CSet Construction) added
expensive regions to CSet, reason: old CSet region num not
reached min, old: 19 regions, expensive: 7 regions, min: 26
regions, remaining time: 0.00 ms]</tt><tt><br>
</tt><tt> 48448.933: [G1Ergonomics (CSet Construction) finish
choosing CSet, eden: 33 regions, survivors: 5 regions, old: 19
regions, predicted pause time: 340.58 ms, target pause time:
250.00 ms]</tt><tt><br>
</tt><tt>48449.252: [SoftReference, 962 refs, 0.0064679
secs]48449.259: [WeakReference, 7411 refs, 0.0027722
secs]48449.261: [FinalReference, 272 refs, 0.0022754
secs]48449.264: [PhantomReference, 6 refs, 0.0024348
secs]48449.266: [JNI Weak Reference, 0.0000337 secs]
48449.288: [G1Ergonomics (Concurrent Cycles) do not request
concurrent cycle initiation, reason: still doing mixed
collections, occupancy: 14898167808 bytes, allocation request:
0 bytes, threshold: 11596411665 bytes (45.00 %), source: end
of GC]</tt><tt><br>
</tt><tt> <b><font color="#ff0000">48449.288</font></b>:
[G1Ergonomics (Mixed GCs) do not continue mixed GCs, reason:
reclaimable percentage not over threshold, candidate old
regions: 156 regions, reclaimable: 2570649712 bytes (9.98 %),
threshold: 10.00 %]</tt><tt><br>
</tt><tt>, 0.3573636 secs]</tt><tt><br>
</tt><tt> [Parallel Time: 314.9 ms, GC Workers: 40]</tt><tt><br>
</tt><tt> [GC Worker Start (ms): Min: 48448933.6, Avg:
48448934.2, Max: 48448934.7, Diff: 1.1]</tt><tt><br>
</tt><tt> [Ext Root Scanning (ms): Min: 15.1, Avg: 17.7,
Max: <b><font color="#00cccc">69.1</font></b>, Diff: 54.0,
Sum: 708.0]</tt><tt><br>
</tt><tt> [Update RS (ms): Min: 0.0, Avg: 14.5, Max: <b><font color="#00cccc">22.2</font></b>, Diff: 22.2, Sum: 580.3]</tt><tt><br>
</tt><tt> [Processed Buffers: Min: 0, Avg: 22.0, Max: <b><font color="#00cccc">45</font></b>, Diff: 45, Sum: 879]</tt><tt><br>
</tt><tt> [Scan RS (ms): Min: 88.7, Avg: 142.6, Max: <b><font color="#00cccc">150.8</font></b>, Diff: 62.1, Sum: 5705.2]</tt><tt><br>
</tt><tt> [Code Root Scanning (ms): Min: 0.0, Avg: 0.0,
Max: <b><font color="#00cccc">0.1</font></b>, Diff: 0.1, Sum:
0.1]</tt><tt><br>
</tt><tt> [Object Copy (ms): Min: 131.4, Avg: 138.2, Max: <b><font color="#00cccc">155.1</font></b>, Diff: 23.8, Sum: 5526.6]</tt><tt><br>
</tt><tt> [Termination (ms): Min: 0.0, Avg: 0.7, Max: <b><font color="#00cccc">0.9</font></b>, Diff: 0.9, Sum: 27.2]</tt><tt><br>
</tt><tt> [GC Worker Other (ms): Min: 0.0, Avg: 0.3, Max: <b><font color="#00cccc">0.5</font></b>, Diff: 0.5, Sum: 10.0]</tt><tt><br>
</tt><tt> [GC Worker Total (ms): Min: 313.2, Avg: 313.9,
Max: <b><font color="#00cccc">314.7</font></b>, Diff: 1.5,
Sum: 12557.5]</tt><tt><br>
</tt><tt> [GC Worker End (ms): Min: 48449247.9, Avg:
48449248.1, Max: 48449248.4, Diff: 0.5]</tt><tt><br>
</tt><tt> [Code Root Fixup: 2.2 ms]</tt><tt><br>
</tt><tt> [Code Root Migration: 0.2 ms]</tt><tt><br>
</tt><tt> [Clear CT: 2.0 ms]</tt><tt><br>
</tt><tt> [Other: 38.2 ms]</tt><tt><br>
</tt><tt> [Choose CSet: 1.7 ms]</tt><tt><br>
</tt><tt> [Ref Proc: 15.6 ms]</tt><tt><br>
</tt><tt> [Ref Enq: 1.2 ms]</tt><tt><br>
</tt><tt> [Free CSet: 2.4 ms]</tt><tt><br>
</tt><tt> [Eden: 1056.0M(1056.0M)->0.0B(1088.0M) Survivors:
160.0M->128.0M Heap: 14.5G(24.0G)->13.9G(24.0G)]</tt><tt><br>
</tt><tt> [Times: user=12.45 sys=0.03, real=0.36 secs] </tt><tt><br>
</tt><tt><b><font color="#ff0000">48454</font></b><b><font color="#ff0000">.034</font></b>: Total time for which
application threads were stopped: <b><font color="#ff0000">9.3426141</font></b>
seconds</tt><tt><br>
</tt><br>
For completeness; here are the cmd line options:<br>
<br>
<br>
/usr/jdk/instances/jdk1.7.0/bin/sparcv9/java -Xms24g -Xmx24g
-server -XX:StringTableSize=27001 -XX:PermSize=512m
-XX:MaxPermSize=512m -Xss512k <br>
-XX:+UseG1GC -XX:SoftRefLRUPolicyMSPerMB=500
-XX:+PrintGCDetails -XX:+PrintGCTimeStamps
-Xloggc:/var/cacao/instances/oem-ec/logs/gc.log
-XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=10
-XX:GCLogFileSize=10m -XX:+PrintGCApplicationStoppedTime
-XX:MaxGCPauseMillis=250-XX:InitiatingHeapOccupancyPercent=45
-XX:+ParallelRefProcEnabled -XX:ParallelGCThreads=40
-XX:+PrintAdaptiveSizePolicy -XX:+PrintSafepointStatistics
-XX:+PrintReferenceGC -XX:G1HeapRegionSize=32m
-XX:HeapBaseMinAddress=2G <br>
</blockquote>
<br>
<br>
The GC starts at 48448.931 and reports that it lasts for 0.36
seconds, so it should have ended at 48449.291. The last log line
that states that the threads were stopped for 9 seconds is from
the PrintGCApplicationStoppedTime flag, which logs how long the
safepoint was. i.e. how long the Java threads where stopped.<br>
<br>
This means that the safepoint lasted for 9 seconds but the GC only
lasted for 0.36 seconds. So the rest of the time must be
attributed to stopping and starting the Java threads. The
safepoint was started at 48444.691 (48454.034 - 9.3426141), which
means that it took 4.240 seconds (48448.931 - 48444.691) to stop
all Java threads and 4.743 seconds (9.3426141 - 4.240 - 0.36) to
start them again. <br>
<br>
I don't have a good explanation for why it takes so long to stop
and start the threads. Are there many Java threads in the
application? Are there many other processes running that could
cause the Java threads to be scheduled out?<br>
<br>
Thanks,<br>
Bengt<br>
<br>
<blockquote cite="mid:54006ED6.7050006@oracle.com" type="cite"> <br>
<br>
<br>
Thanks and Regards<br>
<br>
Thomas <br>
<br>
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