Missing memory
Florian Binder
java at java4.info
Thu May 23 09:36:10 PDT 2013
Ok, I found it:
Statistics for BinaryTreeDictionary:
------------------------------------
Total Free Space: 97824599
Max Chunk Size: 67277447
Number of Blocks: 9063
Av. Block Size: 10793
Tree Height: 67
Statistics for IndexedFreeLists:
--------------------------------
Total Free Space: 322670900
Max Chunk Size: 256
Number of Blocks: 53951619
Av. Block Size: 5
free=420495499 frag=0,9744
They are in the IndexedFreeLists. There seem to be a lot of very small
objects in the old generation, which are removed soon :(
/Flo
Am 23.05.2013 14:47, schrieb Philip Lee:
> Hi,
>
> We have seen a few problems using the CMS collector with JBoss one of which was that the CMS collector does not collect objects that have finalizer() methods. The version of JBoss that we were using (5.1) made heavy use of objects with finalizer() methods within the implementation of its VFS component.
>
> We ended up switching to the parallel collector which gave us maximum pause times of around 5s on a 5G heap.
>
> - Phil
> ________________________________________
> From: hotspot-gc-use-bounces at openjdk.java.net [hotspot-gc-use-bounces at openjdk.java.net] on behalf of Florian Binder [java at java4.info]
> Sent: 23 May 2013 13:25
> To: hotspot-gc-use at openjdk.java.net
> Subject: Missing memory
>
> Hi all,
>
> I am running a jboss application with an embedded h2-database using the
> CMS-Collector.
> It uses the following memory configuration:
> -Xms8G -Xmx8G -Xmn2G
>
> After running a while I got the following interesting issue:
> After a young collection the application uses only 3172435K (8178944K).
> But In the statistics for the BinaryTreeDictionary I see only 1976982
> words (~ 16MB) of Total Free Space. So I am wondering about the 2GB
> which are not used and not in the free list space. Might it be in a TLAB
> or PLAB or where?
>
> The annoying problem of this occurs during the next young collection
> where it does not have enough space in the old generation and fails with
> "promotion failed", which results in a 17s stw collection. After this
> collection I have 446204324 of Total Free Space, which seems correct.
> A concurrent collection is not running due to less usage of the old
> generation.
>
> I am running it on an 8 core machine with
> Java HotSpot(TM) 64-Bit Server VM (build 23.7-b01, mixed mode) (1.7.0_17).
> Detailed information can be found below.
>
> Thank you for your help,
> Flo
>
>
> ############ The startup parameter are: ############
> -server \
> -Xms8G -Xmx8G \
> -Xmn2G \
> -XX:MaxPermSize=256m \
> -verbose:gc \
> -XX:+PrintGC \
> -XX:+PrintGCDateStamps \
> -XX:+PrintGCDetails \
> -XX:+UseConcMarkSweepGC \
> -XX:CMSInitiatingOccupancyFraction=80 \
> -XX:+PrintFlagsFinal \
> -XX:PrintFLSStatistics=1 \
> -XX:+PrintTenuringDistribution \
> -XX:+PrintGCApplicationConcurrentTime \
> -XX:+PrintGCApplicationStoppedTime \
> -XX:+UseLargePages \
> -XX:LargePageSizeInBytes=4m \
>
> ############ The relevant gc-log snippet: ############
> 2013-05-23T01:04:57.536-0400: [GC Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 4459853
> Max Chunk Size: 2117113
> Number of Blocks: 10
> Av. Block Size: 445985
> Tree Height: 6
> Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 6837777
> Max Chunk Size: 6832640
> Number of Blocks: 6
> Av. Block Size: 1139629
> Tree Height: 5
> [ParNew
> Desired survivor size 107347968 bytes, new threshold 2 (max 6)
> - age 1: 59250760 bytes, 59250760 total
> - age 2: 72435232 bytes, 131685992 total
> : 1887488K->206257K(1887488K), 0,1177960 secs]
> 4788275K->3172435K(8178944K)After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1976982
> Max Chunk Size: 1969801
> Number of Blocks: 2
> Av. Block Size: 988491
> Tree Height: 2
> After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 6837777
> Max Chunk Size: 6832640
> Number of Blocks: 6
> Av. Block Size: 1139629
> Tree Height: 5
> , 0,1179200 secs] [Times: user=0,80 sys=0,00, real=0,12 secs]
> Total time for which application threads were stopped: 0,1186510 seconds
> Application time: 0,7920070 seconds
> 2013-05-23T01:04:58.447-0400: [GC Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1976982
> Max Chunk Size: 1969801
> Number of Blocks: 2
> Av. Block Size: 988491
> Tree Height: 2
> Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 6837777
> Max Chunk Size: 6832640
> Number of Blocks: 6
> Av. Block Size: 1139629
> Tree Height: 5
> [ParNew (promotion failed)
> Desired survivor size 107347968 bytes, new threshold 2 (max 6)
> - age 1: 57903280 bytes, 57903280 total
> - age 2: 52076168 bytes, 109979448 total
> : 1884081K->1878750K(1887488K), 2,5295040 secs][CMSCMS: Large block
> 0x000000071b3bb2e0
> : 3020224K->2805356K(6291456K), 15,0643760 secs]
> 4850259K->2805356K(8178944K), [CMS Perm : 80257K->79027K(133764K)]After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 446204324
> Max Chunk Size: 446204324
> Number of Blocks: 1
> Av. Block Size: 446204324
> Tree Height: 1
> After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 0
> Max Chunk Size: 0
> Number of Blocks: 0
> Tree Height: 0
> , 17,5940190 secs] [Times: user=18,00 sys=0,78, real=17,59 secs]
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