Re: [Wrapper-user] wrapper.java.maxmemory.percent=100 does not work on 32-bit Systems with more than 1.6GB Ram installed.

[Leif M. <le...@ta...>]

Markus,
3.3.1 was released today with a fix which now sets the 100% memory
size to 2GB or the amount of physical memory for 32-bit versions of
the Wrapper.  This is not quite what you asked for but it should
improve things for you.  This should make it more correct to set the
value to something like 75%.

I was not going to have time to implement this as you asked and really
needed to get the release out the door.

What are your thoughts after trying out 3.3.1?

Cheers,
Leif

On Mon, Aug 18, 2008 at 8:04 PM, Markus Schlegel <sc...@gm...> wrote:
> Hi
> We're using Wrapper Std Edition 3.3.0.
> We would like to use the wrapper.java.maxmemory.percent properties in our
> installation files. Since we do not know the memorysize of the target
> machines, this has the advantage that our application can be installed
> without the need to configure the maxmemory setting by the customer.
>
> The problem now is, that a JVM (at least under Windows) can not get 100% of
> the physical RAM for it's heap. It can only get as much RAM as there is
> contiguous space available when the JVM starts. Since the OS already uses
> some parts of the physical RAM, there will never be the full size available.
> Moreover, even if there is plenty of RAM available, a 32-bit JVM will not be
> able to start when Xmx is set to a value larger than approx. 1600m (the
> exact value depends on the machines configuration somehow). This limit comes
> from the maximum amount of RAM availabvle for a 32-bit Process (which is
> 2GB) minus the amount of RAM used for the parts of the JVM that will not be
> part of the Heap (I guess). We have such a configuration on nearly all
> target machines we are currently installing our software, since RAM is
> cheap...
>
> You could now say, that the solution could be, to set the percentage value
> to 75%. But this would work only for machines having at most 2GB of RAM.
> For 32-bit VM's with more RAM installed on the machine, the maximum value of
> the Xmx-setting should not be 2GB, but somewhere between 1.4 and 1.6 GB
> (WinRun4J uses 1530MB).
>
> So it seems, that setting the -Xmx value from a percentage should use some
> system function which checks for the available contiguous Ram and respects
> the maximum heap size of for example 1530m on 32 bit systems.
>
> Regards,
>
> Markus Schlegel, pulinco engineering ag
>
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