Pauses with the CMS

mrk mrk at autocom.dk
Fri Oct 29 00:22:25 PDT 2010


I will let you know. We are currently waiting on our hosting center to 
install the new JDK.

med venlig hilsen / Best regards,
Morten Knudsen

"Y. S. Ramakrishna" 
<y.s.ramakrishna at oracle.com> skrev i 
meddelelsen news:4CC9AA53.4070109 at oracle.com...
>
>
> On 10/28/10 01:48, mrk wrote:
>> Hi
>>
>> Isn't u22 good enough? I'm not too keen on using PreRelease software.
>
> Yes, i just checked and it seems to be fixed in 6u22:-
>
> java version "1.6.0_22"
> Java(TM) SE Runtime Environment (build 1.6.0_22-b04)
> Java HotSpot(TM) Server VM (build 17.1-b03, mixed mode)
>
> Let us know how it goes.
> -- ramki
>
>>
>> med venlig hilsen / Best regards,
>> Morten Knudsen
>>
>> "Y. Srinivas Ramakrishna" 
>> <y.s.ramakrishna at oracle.com> skrev i 
>> meddelelsen news:4CC92E90.8090301 at oracle.com...
>>> Hi Morten --
>>>
>>> On 10/28/2010 12:40 AM, mrk wrote:
>>>> Hi Ramki
>>>>
>>>> Thanks for your answer. I have read the CR description. It mentions 
>>>> NIO. We do not use the NIO
>>>> connector in Tomcat. Could the CR be affecting us anyway?
>>>
>>> It need not be NIO, but it could be something else perhaps not directly 
>>> used
>>> by you but indirectly through the core JDK libraries that makes use of
>>> JNI Critical Sections (NIO used to use that mechanism until recently
>>> but no longer does).
>>>
>>> I think it's worth a try, since the symptoms you describe are very 
>>> similar to
>>> 6919638. Try the workaround or 6u23/JDK 7 latest and, if it doesn't 
>>> work,
>>> closer investigation will be warranted, at which time you will want to
>>> open a ticket via your support channels and/or provide a test case
>>> exhibiting the problem.
>>>
>>> best regards.
>>> -- ramki
>>>
>>>>
>>>> med venlig hilsen / Best regards,
>>>> Morten Knudsen
>>>>
>>>> "Y. S. Ramakrishna" 
>>>> <y.s.ramakrishna at oracle.com> skrev i 
>>>> meddelelsen
>>>> news:4CC84F4E.2080302 at oracle.com...
>>>>> There were two related CR's which may be affecting you:
>>>>>
>>>>> (1) 6692906 CMS: parallel concurrent marking may be prone to hanging 
>>>>> or stalling mutators for
>>>>> periods of time
>>>>> I do not think this is affecting you.
>>>>>
>>>>> (2) 6919638 CMS: ExplicitGCInvokesConcurrent misinteracts with gc 
>>>>> locker
>>>>>
>>>>> I suspect it could be this latter CR that's affecting you. If so, it's
>>>>> fixed in 6u22 and in 6u23 (and in 7 since 7bb95), so you might want to
>>>>> try those. There's also a workaround documented in the CR.
>>>>>
>>>>> -- ramki
>>>>>
>>>>>
>>>>> On 10/27/10 01:50, mrk wrote:
>>>>>> Hi All
>>>>>>
>>>>>> Hi
>>>>>>
>>>>>> We have made a webapp running in JBoss 4.2.3 on RedHat Linux 5.2 on a 
>>>>>> 12 core IBM machine. Lately
>>>>>> we have seen long response times, which seems to be caused be GC 
>>>>>> activities. The pattern is more
>>>>>> or less as follows:
>>>>>> All requests seem to come at normal rate, but no bytes are sent until 
>>>>>> suddenly all responses are
>>>>>> "flushed".
>>>>>> At same time the gc.log has this pattern:
>>>>>>
>>>>>> // Here the unresponsiveness starts
>>>>>> 36788.309: [GC [1 CMS-initial-mark: 1919297K(4456448K)] 
>>>>>> 1969797K(5111808K), 0.1473460 secs]
>>>>>> [Times: user=0.15 sys=0.00, real=0.15 secs]
>>>>>> Total time for which application threads were stopped: 0.1530790 
>>>>>> seconds
>>>>>> 36788.457: [CMS-concurrent-mark-start]
>>>>>> 36793.886: [CMS-concurrent-mark: 5.429/5.429 secs] 
>>>>>> (CMS-concurrent-mark yielded 46 times)
>>>>>> [Times: user=6.69 sys=0.07, real=5.43 secs]
>>>>>> 36793.886: [CMS-concurrent-preclean-start]
>>>>>> (cardTable: 15956 cards, re-scanned 15956 cards, 1 iterations)
>>>>>> 36793.988: [CMS-concurrent-preclean: 0.089/0.101 secs] 
>>>>>> (CMS-concurrent-preclean yielded 9 times)
>>>>>> [Times: user=0.12 sys=0.01, real=0.10 secs]
>>>>>> 36793.988: [CMS-concurrent-abortable-preclean-start]
>>>>>> (cardTable: 75 cards, re-scanned 75 cards, 1 iterations)
>>>>>> Application time: 5.6923460 seconds
>>>>>> Total time for which application threads were stopped: 0.0170000 
>>>>>> seconds
>>>>>> (cardTable: 96 cards, re-scanned 96 cards, 1 iterations)
>>>>>> (cardTable: 207 cards, re-scanned 207 cards, 1 iterations)
>>>>>> (cardTable: 45 cards, re-scanned 45 cards, 1 iterations)
>>>>>> (cardTable: 157 cards, re-scanned 157 cards, 1 iterations)
>>>>>> (cardTable: 88 cards, re-scanned 88 cards, 1 iterations)
>>>>>> (cardTable: 213 cards, re-scanned 213 cards, 1 iterations)
>>>>>> (cardTable: 84 cards, re-scanned 84 cards, 1 iterations)
>>>>>> (cardTable: 143 cards, re-scanned 143 cards, 1 iterations)
>>>>>> (cardTable: 40 cards, re-scanned 40 cards, 1 iterations)
>>>>>> (cardTable: 109 cards, re-scanned 109 cards, 1 iterations)
>>>>>> (cardTable: 77 cards, re-scanned 77 cards, 1 iterations)
>>>>>> (cardTable: 156 cards, re-scanned 156 cards, 1 iterations)
>>>>>> (cardTable: 132 cards, re-scanned 132 cards, 1 iterations)
>>>>>> (cardTable: 119 cards, re-scanned 119 cards, 1 iterations)
>>>>>> (cardTable: 115 cards, re-scanned 115 cards, 1 iterations)
>>>>>> (cardTable: 195 cards, re-scanned 195 cards, 1 iterations)
>>>>>> (cardTable: 163 cards, re-scanned 163 cards, 1 iterations)
>>>>>> (cardTable: 166 cards, re-scanned 166 cards, 1 iterations)
>>>>>> (cardTable: 149 cards, re-scanned 149 cards, 1 iterations)
>>>>>> (cardTable: 218 cards, re-scanned 218 cards, 1 iterations)
>>>>>> (cardTable: 46 cards, re-scanned 46 cards, 1 iterations)
>>>>>> (cardTable: 57 cards, re-scanned 57 cards, 1 iterations)
>>>>>> (cardTable: 213 cards, re-scanned 213 cards, 1 iterations)
>>>>>> (cardTable: 189 cards, re-scanned 189 cards, 1 iterations)
>>>>>> (cardTable: 104 cards, re-scanned 104 cards, 1 iterations)
>>>>>> (cardTable: 60 cards, re-scanned 60 cards, 1 iterations)
>>>>>> (cardTable: 368 cards, re-scanned 368 cards, 1 iterations)
>>>>>> (cardTable: 118 cards, re-scanned 118 cards, 1 iterations)
>>>>>> (cardTable: 129 cards, re-scanned 129 cards, 1 iterations)
>>>>>> (cardTable: 291 cards, re-scanned 291 cards, 1 iterations)
>>>>>> (cardTable: 105 cards, re-scanned 105 cards, 1 iterations)
>>>>>> (cardTable: 63 cards, re-scanned 63 cards, 1 iterations)
>>>>>> (cardTable: 73 cards, re-scanned 73 cards, 1 iterations)
>>>>>> (cardTable: 165 cards, re-scanned 165 cards, 1 iterations)
>>>>>> (cardTable: 69 cards, re-scanned 69 cards, 1 iterations)
>>>>>> (cardTable: 157 cards, re-scanned 157 cards, 1 iterations)
>>>>>> CMS: abort preclean due to time [37 iterations, 13 waits, 4954 
>>>>>> cards)] 36799.161:
>>>>>> [CMS-concurrent-abortable-preclean: 2.965/5.173 secs] 
>>>>>> (CMS-concurrent-abortable-preclean yielded
>>>>>> 166 times)
>>>>>> [Times: user=5.12 sys=0.10, real=5.17 secs]
>>>>>> Application time: 4.9945030 seconds
>>>>>> 36799.172: [GC[YG occupancy: 572074 K (655360 K)]36799.172: [GC 
>>>>>> 36799.173: [ParNew
>>>>>> Desired survivor size 67108864 bytes, new threshold 2 (max 15)
>>>>>> - age 1: 59654872 bytes, 59654872 total
>>>>>> - age 2: 26827232 bytes, 86482104 total
>>>>>> - age 3: 2613360 bytes, 89095464 total
>>>>>> - age 4: 929600 bytes, 90025064 total
>>>>>> - age 5: 893176 bytes, 90918240 total
>>>>>> - age 6: 795736 bytes, 91713976 total
>>>>>> - age 7: 809240 bytes, 92523216 total
>>>>>> - age 8: 936216 bytes, 93459432 total
>>>>>> - age 9: 971376 bytes, 94430808 total
>>>>>> - age 10: 624472 bytes, 95055280 total
>>>>>> - age 11: 883616 bytes, 95938896 total
>>>>>> - age 12: 817296 bytes, 96756192 total
>>>>>> - age 13: 977992 bytes, 97734184 total
>>>>>> - age 14: 733816 bytes, 98468000 total
>>>>>> - age 15: 654744 bytes, 99122744 total
>>>>>> : 572074K->110988K(655360K), 0.1855140 secs] 
>>>>>> 2491372K->2031059K(5111808K) icms_dc=0 , 0.1866380
>>>>>> secs] [Times: user=0.72 sys=0.00, real=0.19 secs]
>>>>>> 36799.359: [Rescan (parallel) (Survivor:12chunks) Finished young gen 
>>>>>> rescan work in 3th thread:
>>>>>> 0.032 sec
>>>>>> Finished young gen rescan work in 2th thread: 0.035 sec
>>>>>> Finished young gen rescan work in 0th thread: 0.035 sec
>>>>>> Finished young gen rescan work in 1th thread: 0.035 sec
>>>>>> Finished remaining root rescan work in 1th thread: 0.030 sec
>>>>>> Finished remaining root rescan work in 3th thread: 0.033 sec
>>>>>> Finished remaining root rescan work in 2th thread: 0.032 sec
>>>>>> Finished remaining root rescan work in 0th thread: 0.042 sec
>>>>>> Finished dirty card rescan work in 2th thread: 0.029 sec
>>>>>> Finished dirty card rescan work in 3th thread: 0.031 sec
>>>>>> Finished dirty card rescan work in 0th thread: 0.019 sec
>>>>>> Finished dirty card rescan work in 1th thread: 0.031 sec
>>>>>> Finished work stealing in 3th thread: 0.000 sec
>>>>>> Finished work stealing in 0th thread: 0.000 sec
>>>>>> Finished work stealing in 2th thread: 0.000 sec
>>>>>> Finished work stealing in 1th thread: 0.000 sec
>>>>>> , 0.0959640 secs]36799.455: [weak refs processing, 0.0121220 secs] [1 
>>>>>> CMS-remark:
>>>>>> 1920070K(4456448K)] 2031059K(5111808K), 0.2952350 secs] [Times: 
>>>>>> user=1.11 sys=0.00, real=0.30 secs]
>>>>>> Total time for which application threads were stopped: 0.3066430 
>>>>>> seconds
>>>>>> 36799.468: [CMS-concurrent-sweep-start]
>>>>>> 36805.824: [CMS-concurrent-sweep: 6.355/6.356 secs] 
>>>>>> (CMS-concurrent-sweep yielded 515 times)
>>>>>> [Times: user=8.76 sys=0.24, real=6.35 secs]
>>>>>> 36805.824: [CMS-concurrent-reset-start]
>>>>>> 36805.903: [CMS-concurrent-reset: 0.079/0.079 secs] 
>>>>>> (CMS-concurrent-reset yielded 0 times)
>>>>>> [Times: user=0.64 sys=0.01, real=0.07 secs]
>>>>>> Application time: 6.5590510 seconds
>>>>>> // About here the server starts sending out responses
>>>>>> 36806.044: [GC 36806.045: [ParNew
>>>>>> Desired survivor size 67108864 bytes, new threshold 2 (max 15)
>>>>>> - age 1: 55456640 bytes, 55456640 total
>>>>>> - age 2: 54278984 bytes, 109735624 total
>>>>>> : 635276K->131072K(655360K), 0.3230430 secs] 
>>>>>> 2554507K->2089990K(5111808K) icms_dc=0 , 0.3242750
>>>>>> secs] [Times: user=1.02 sys=0.02, real=0.33 secs]
>>>>>> Total time for which application threads were stopped: 0.3422430 
>>>>>> seconds
>>>>>> Application time: 0.7628480 seconds
>>>>>>
>>>>>> We have tried various GC setups, but we always end up more or less 
>>>>>> like this.
>>>>>> Our current parameters:
>>>>>> -Xms4096m -Xmx5120m -XX:MaxPermSize=384m
>>>>>> -XX:+UseConcMarkSweepGC -XX:+ExplicitGCInvokesConcurrent
>>>>>> -XX:+PrintClassHistogram -XX:+PrintGCApplicationConcurrentTime -XX:+PrintGCApplicationStoppedTime
>>>>>> -XX:+PrintGCDetails
>>>>>> -XX:ReservedCodeCacheSize=64m -XX:NewSize=768m -XX:SurvivorRatio=4
>>>>>> -XX:+CMSParallelRemarkEnabled -XX:+CMSScavengeBeforeRemark -XX:+CMSIncrementalMode
>>>>>> -XX:+CMSIncrementalPacing -XX:CMSIncrementalDutyCycleMin=0 -XX:CMSIncrementalDutyCycle=10
>>>>>> -XX:+UseTLAB -XX:ParallelGCThreads=4
>>>>>> -XX:+UseParNewGC -XX:MaxGCPauseMillis=1000 -XX:GCTimeRatio=10 -XX:+CMSPermGenSweepingEnabled
>>>>>> -XX:+PrintCMSInitiationStatistics -XX:PrintCMSStatistics=1 -XX:+PrintGCTaskTimeStamps
>>>>>> -XX:+PrintGCTimeStamps
>>>>>> -verbose:gc -XX:+TraceClassLoading -XX:+TraceClassUnloading
>>>>>> -XX:+PrintTenuringDistribution
>>>>>>
>>>>>> How can we avoid the unresponsiveness?
>>>>>>
>>>>>> We have tried with both JDK 1.6.0_06 and JDK 1.6.0_021.
>>>>>>
>>>>>> It seems that the problem have a lot in common with:
>>>>>> http://old.nabble.com/long-unaccounted-pause-during-concurrent-mark-phase-of-ParNew-cycle-to27459365.html#a27463304
>>>>>> But setting -XX:-CMSConcurrentMTEnabled does not seem to help?
>>>>>>
>>>>>> med venlig hilsen / Best regards,
>>>>>> Morten Knudsen
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>
>>
> 




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