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Posted to users@netbeans.apache.org by Thomas Wolf <tj...@gmail.com> on 2022/12/05 20:20:51 UTC

Why is max heap under NB different than outside it?

I was running my J2SE application inside of NB and with a large data set ran out of heap space.  I don’t specify a -Xmx arg for my app and I was curious why with 32GB of physical memory that should happen.  I ran the application again and, from the command-line, did
	jinfo -flag MaxHeapSize xxx (xxx is my app’s process id)
to see how much heap the JVM decided to allocate.  It returned
	-XX:MaxHeapSize=4294967296
Weird - that’s 1/8th of my physical memory.  If memory served, Java was supposed to use up to 1/4th physical memory for max heap size.  So I ran the application again - this time straight from the command-line rather than from inside NB.   And outside of NB, jinfo reported the expected 8GB of heap:
	-XX:MaxHeapSize=8589934592

Does anyone know why that is?

Although I doubt it matters, I’m running on macOS 13.1, NB 13, with NB and my app both using JDK/JRE 17.

thanks,
Tom





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Re: Why is max heap under NB different than outside it?

Posted by Thomas Wolf <tj...@gmail.com>.
Never mind - the stupid bug struck hard (long time ago I must’ve set the 4GB as a VM option in the configuration I was using).
Sorry about the noise.
tom


> On Dec 5, 2022, at 3:20 PM, Thomas Wolf <tj...@gmail.com> wrote:
> 
> 
> I was running my J2SE application inside of NB and with a large data set ran out of heap space.  I don’t specify a -Xmx arg for my app and I was curious why with 32GB of physical memory that should happen.  I ran the application again and, from the command-line, did
> 	jinfo -flag MaxHeapSize xxx (xxx is my app’s process id)
> to see how much heap the JVM decided to allocate.  It returned
> 	-XX:MaxHeapSize=4294967296
> Weird - that’s 1/8th of my physical memory.  If memory served, Java was supposed to use up to 1/4th physical memory for max heap size.  So I ran the application again - this time straight from the command-line rather than from inside NB.   And outside of NB, jinfo reported the expected 8GB of heap:
> 	-XX:MaxHeapSize=8589934592
> 
> Does anyone know why that is?
> 
> Although I doubt it matters, I’m running on macOS 13.1, NB 13, with NB and my app both using JDK/JRE 17.
> 
> thanks,
> Tom
> 
> 
> 
> 


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