[jira] Commented: (HARMONY-3152) [drlvm][gc] Harmony silently not paying attention to -Xms -Xmx

["Chris Elford (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HARMONY-3152?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12496955 ] 

Chris Elford commented on HARMONY-3152:
---------------------------------------

Hi Xiao Feng,

  I expect that the behavior w/ GCV5 will be different from GCV4.1.  It should be fairly easy.  Let me know if you need anything from me.

Thx,

Chris

> [drlvm][gc] Harmony silently not paying attention to -Xms -Xmx
> --------------------------------------------------------------
>
>                 Key: HARMONY-3152
>                 URL: https://issues.apache.org/jira/browse/HARMONY-3152
>             Project: Harmony
>          Issue Type: Bug
>          Components: DRLVM
>         Environment: EM64T -- Redhat EL 4 - Update 4
>            Reporter: Chris Elford
>         Assigned To: Xiao-Feng Li
>
> Testing hello world with different heap sizes now that the 2GB segfault bug has been fixed in the binary snapshot version of Harmony.  It appears that Harmony silently ignores -Xms and Xmx options when it chooses to do so.  This is different from the RI and is not the expected behavior.
> [root@celford-dev64 jrun]# /opt/harmony-jre-r505120/bin/java -Xms2g -Xmx2g hello
> Hello World! 0 b50b98e0
> Totalmemory = 2048.000000 GB
> [root@celford-dev64 jrun]# /opt/harmony-jre-r505120/bin/java -Xms4g -Xmx4g hello
> Hello World! 0 cea53278
> Totalmemory = 4096.000000 GB
> [root@celford-dev64 jrun]# /opt/harmony-jre-r505120/bin/java -Xms8g -Xmx8g hello
> Hello World! 0 cea53278
> Totalmemory = 4096.000000 GB
> [root@celford-dev64 jrun]# /opt/harmony-jre-r505120/bin/java -Xms16g -Xmx16g hello
> Hello World! 0 cea53278
> Totalmemory = 4096.000000 GB
> [root@celford-dev64 jrun]# /opt/harmony-jre-r505120/bin/java -Xms32g -Xmx32g hello
> Hello World! 0 cea53278
> Totalmemory = 4096.000000 GB
> [root@celford-dev64 jrun]# /opt/harmony-jre-r505120/bin/java -Xms32000g -Xmx32000g hello
> Hello World! 0 cea53278
> Totalmemory = 4096.000000 GB
> Reference implementation:
> [root@celford-dev64 jrun]# /opt/jre5/bin/java -Xms2g -Xmx2g hello
> Hello World! 0 5acac268
> Totalmemory = 1962.687500 GB
> [root@celford-dev64 jrun]# /opt/jre5/bin/java -Xms4g -Xmx4g hello
> Hello World! 0 5acac268
> Totalmemory = 3925.375000 GB
> [root@celford-dev64 jrun]# /opt/jre5/bin/java -Xms8g -Xmx8g hello
> Hello World! 0 5acac268
> Totalmemory = 7850.687500 GB
> [root@celford-dev64 jrun]# /opt/jre5/bin/java -Xms16g -Xmx16g hello
> Error occurred during initialization of VM
> Could not reserve enough space for object heap
> The Totalmemory print in hello world looks like 
>         System.out.printf("Totalmemory = %f GB\n",Runtime.getRuntime().totalMemory()/1024.0/1024.0);
> Adding -Xverbose with Harmony shows what is going on.  The heap is being silently truncated to a size smaller than the min heap size specified by the user and the max heap is set to a different size than that specified by the user:
> maximum heap size is limited to 4 Gb due to pointer compression
> GC v4.1  (release)
> GC type = 0
> GC will use adaptive algorithm selection
> min heap size 4096 mb
> max heap size 4096 mb
> GC use small pages
> If -Xms and -Xmx heap sizes cannot be honored, harmony should not silently proceed with a different heap size.  

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