[Mulgara-dev] XAFix Impl notes

[David Moll]

"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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