Java heap size is not accessing all available RAM

Hi,

I am currently running 64-bit Matlab (making use of 64-bit Java) on a server with 128GB of RAM. Matlab version is R2016a.

In my Matlab preferences, I cannot increase the Java heap size beyond 32GB - this is causing my code to fail (it is unable to read ~70 million rows of data from SQL).

This has worked in the past, and the java heap size setting gave me the option to slide across to 128GB, but as I said it is now only letting me increase to 32GB.

I am not in a position to change the code - this was written by someone else, and I do not have the sign off to change this at the moment.

Any help will be appreciated.

Thanks,

[Jan]

What has happened between "the past" and "now"? What does this mean: "I do not have the sign off to change this"?

[Walter Roberson]

"I do not have the sign off to change this" means that the person does not have the authority to make any changes to the code, only to the running environment.

[Atifah]

Nothing in the code has changed - the dataset is slightly larger, but this is not causing the problem because I have tried to run on subsets too. There have probably been some infrastructure changes since it was last run (but the server has the same processing power).

"No sign off to change" means I have not been assigned the time to make major changes to the code (it needs a big rewrite, but has worked in the past). The answer below has actually fixed it - thanks all!

Answer 1

[Prannay Jain]

If the maximum value, allowed by this slider, is too small for the requirements, it could be directly adjusted by editing:

"C:\Users\%USERNAME%\AppData\Roaming\MathWorks\MATLAB\%matlabversion%\matlab.prf"

You can get this path using,

>> prefdir

1. Open this file with a text editor.

2. Modify "JavaMemHeapMax" value. It should look like

JavaMemHeapMax=I128000

3. Restart MATLAB for changes to reflect.

The Preferences UI will display a warning in Java Heap Memory, that it is larger than recommended.

[Atifah]

Thank you so much! This worked - I have tried so many things before posting this question.