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[protege-discussion] Protege 3.4.4 (579) 64-bit max heap size

Timothy Redmond tredmond at
Fri Sep 3 23:18:54 PDT 2010

On Sep 3, 2010, at 6:47 PM, Len Yabloko wrote:

> Thank you for all responces. I spent much of the day trying to use  
> all available memory for loading Protege frames. The best result I  
> got was with
> -XX:MaxPermSize=3000M, although I am not sure that was it. Here is  
> the screenshot of Windows 7 task manager showing the big plato and  
> then sudden jump at the end. Can someone explain it?

I would guess  that such a MaxPermSize is not recommended - it is far  
too large.  I am a bit uncertain as to what the issue is here.  Are  
you getting OutOfMemory errors and if so what do they look like?  Do  
they mention the PermGen space?  Simply not using the memory may not  
be a problem.  Are you trying to reduce the amount of garbage  
collection that is occurring?

Setting the initial heap size with -Xms will give java the hint that  
you want to allocate more  space up front.  It is often recommended  
that the Xmx and Xms get set at the same time for the reason that  
Peris  gives below.  But this also makes java allocate space even if  
it doesn't need it.


>> I would try setting the initial heap size, as well (-Xms6g).   
>> Otherwise, the
>> heap must be grown over the runtime in possibly many smaller  
>> chunks, which
>> can slow performance.
>> -Peris
>> On Fri, Sep 3, 2010 at 12:57 PM, Len Yabloko  
>> <protege at> wrote:
>>> Hello everyone,
>>> I am running latest Protege Frames version on Windows 7 64-bit and  
>>> trying
>>> to generate a very large frame ontology by loading data from MySQL  
>>> database
>>> using frame API. I have allocated 6G to jvm and checked  
>>> Runtime.maxMemory()
>>> to verify that is was correctly allocated. But for some reason  
>>> when memory
>>> reaches about 2.5G (according to Windows task manager) it stops  
>>> allocating
>>> and loading slows after about 15,000 frames loaded. I tried  
>>> launching
>>> Protege with -vmargs -Xmx6g using 64-bit jvm, but no luck so far.
>>> Can someone suggest what may be a cause of such behavior?
>>> _______________________________________________
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>> -- 
>> “Ah, but a man's reach should exceed his grasp, or what's a heaven  
>> for?”
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