[Mulgara-dev] XAFix Impl notes

[Tate Jones]

I would certainly not increase the memory that high eg. Xmn and Xmx  
to 3Gb.  You are actually hurting the performance.  It is probably  
worst than the standard JVM settings.  The triple store relies on  
mapped i/o outside the JVM.  By increasing the memory that high you  
have removed the available memory from the OS.  By setting the Xmn at  
3Gb I believe you have immediately obtained 3Gb of memory via the  
young generation.  I maybe wrong here.

Please send me (tar or zipped) of the -verbose:gc output.

Been involved in many performance tuning projects, I would not  
increase the Xmx above 1500mb.    I would be very surprise if Mulgara  
is using more than 256Mb with 50 concurrent sessions.

Please try -Xms 256mb -Xmx256mb and -Xms512mb -Xmx512mb with -verbose:gc

On 15/12/2006, at 4:45 AM, David Moll wrote:

> “Run with -verbose:gc -XX:+PrintGCTimeStamps -XX:+PrintGCDetails  
> for accurate memory and gc activity.
>
>
>
> I doubt you are using 1Gb as you command line indicates no Xmx  
> setting.  Therefore you are at a max of 256Mb (server mode) I   
> believe.
>
>
>
> By design Mulgara shouldn't use much memory. However increasing the  
> number of concurrent sessions will increase memory requirements.”
>
>
>
> I set up to run with the GC messages, but it was too verbose.  I  
> did some digging and figured out how to use jconsole for monitoring  
> the processes.  To do this I needed to change the invocation of the  
> jvm to:
>
>
>
>  “java -Dcom.sun.management.jmxremote -jar mulgara-1.0.0.jar –l”
>
>
>
> In order for jconsole to recognize the jvm as a process that it  
> could attach itself to.  The information provided was quite  
> interesting, and it provides much more detailed information than  
> the Windows Task Manager can.  I wanted to see what would happen  
> when I did a restore.  I deleted the server1 directory, started up  
> Mulgara, attached the jconsole and began a restore.  Our backup  
> file is 153 MB.  The restore takes roughly 1,100 seconds when  
> restoring the backup.gz into an empty metastore.  Windows Task  
> Manager claims that the memory usage goes up to around 3 GB (it  
> actually showed that it peaked at 3.7 GB this time), but I’m  
> reasonably certain that’s just the JVM and the OS disagreeing about  
> who currently owns what pages.
>
>
>
> The jconsole showed that the JVM never went above 500 MB of memory  
> used, and the vast majority of it was in the heap.  We have tried  
> several different command line options for the JVM, always with the  
> values for –Xmn and –Xmx equal to one another.  On production right  
> now we have the JVM with TKS2.1 set up with –Xmn and –Xmx both at 3GB.
>
>
>
> We are looking forward to replacing TKS2.1 with Mulgara.
>
>
>
> ~Dave
>
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Tate Jones
tate at bluedog.com.au