You are viewing a plain text version of this content. The canonical link for it is here.
Posted to users@jena.apache.org by Iain Ritchie <ia...@gmail.com> on 2013/09/03 13:54:13 UTC
Suggested JVM Settings
Hi,
Can anyone suggested optimum JVM memory settings when starting Fuseki? i.e.
-xmx and -xms flags
Machine is Windows 64 bit, 16GB RAM, 64 bit JVM.
I know this is somewhat application specific but want to pick something
sensible in the first instance.
Many Thanks.
Re: Suggested JVM Settings
Posted by Adrian Gschwend <ml...@netlabs.org>.
On 03.09.13 16:45, Andy Seaborne wrote:
> I'd expect them to be the same but I don't have any input to confirm
> that. Do you have any figures?
Problem is that currently I don't run the systems on the same hardware
so it's not possible to directly compare results right now. If I find
some time I will try to do some tests on my data set. I do have some
queries which need quite some time to complete.
I also want to compare them to the DB2 backend which IBM now offers for
Fuseki (instead of TDB). Wonder if it really is faster or if they just
claim it is :)
> I currently think its a windows matter in the handling of mmap files
> (from java).
yeah can imagine that the JVM has to do something there. AFAIK it's
called File Mapping on Windows API.
regards
Adrian
Re: Suggested JVM Settings
Posted by Andy Seaborne <an...@apache.org>.
On 03/09/13 15:37, Adrian Gschwend wrote:
> On 03.09.13 16:26, Andy Seaborne wrote:
>
>> But mmap files do not give the speed up as they do on Linux. It's been
>> reported as being neutral. It still flexs the memory size and avoids
>> the need to size the heap at start-up.
>
> ok thanks for the clarification. Is there a difference between Linux and
> other Unixes or should this be pretty much the same? I run Fuseki on
> FreeBSD and Solaris as well.
I'd expect them to be the same but I don't have any input to confirm
that. Do you have any figures?
I currently think its a windows matter in the handling of mmap files
(from java).
Andy
>
> regards
>
> Adrian
>
Re: Suggested JVM Settings
Posted by Adrian Gschwend <ml...@netlabs.org>.
On 03.09.13 16:26, Andy Seaborne wrote:
> But mmap files do not give the speed up as they do on Linux. It's been
> reported as being neutral. It still flexs the memory size and avoids
> the need to size the heap at start-up.
ok thanks for the clarification. Is there a difference between Linux and
other Unixes or should this be pretty much the same? I run Fuseki on
FreeBSD and Solaris as well.
regards
Adrian
Re: Suggested JVM Settings
Posted by Andy Seaborne <an...@apache.org>.
On 03/09/13 14:30, Adrian Gschwend wrote:
> On 03.09.13 14:53, Andy Seaborne wrote:
>
> Hi Andy,
>
>> TDB will use the rest of unused memory via memory mapped files - these
>> are not part of the heap and don't count for -Xmx.
>
> Is this true for all platforms or only Unix? Thought you once mentioned
> that this is not available on Windows.
It is available, and used, on Windows/64 bit.
But mmap files do not give the speed up as they do on Linux. It's been
reported as being neutral. It still flexs the memory size and avoids
the need to size the heap at start-up.
(I don't run TDB on Windows much so how the OS schedules and manages RAM
in this situation is a bit of a mystery to me.)
There is a windows-specific Java bug in not being able to delete entire
databases while the JVM is running.
Andy
>
> regards
>
> Adrian
>
Re: Suggested JVM Settings
Posted by Adrian Gschwend <ml...@netlabs.org>.
On 03.09.13 14:53, Andy Seaborne wrote:
Hi Andy,
> TDB will use the rest of unused memory via memory mapped files - these
> are not part of the heap and don't count for -Xmx.
Is this true for all platforms or only Unix? Thought you once mentioned
that this is not available on Windows.
regards
Adrian
Re: Suggested JVM Settings
Posted by Andy Seaborne <an...@apache.org>.
On 03/09/13 12:54, Iain Ritchie wrote:
> Hi,
>
> Can anyone suggested optimum JVM memory settings when starting Fuseki? i.e.
> -xmx and -xms flags
>
> Machine is Windows 64 bit, 16GB RAM, 64 bit JVM.
>
> I know this is somewhat application specific but want to pick something
> sensible in the first instance.
For Fuseki, about 2G for heap if using TDB.
TDB will use the rest of unused memory via memory mapped files - these
are not part of the heap and don't count for -Xmx.
Andy
>
> Many Thanks.
>