MATLAB: How to monitor how much memory MATLAB is using

dumpmemMATLAB

I have a program that is memory intensive and I want to monitor how much memory MATLAB is using so that if it goes above a certain threshold, I can stop the program.

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Unfortunately, there is not a convenient way to monitor memory usage in MATLAB. However, the attached function can help monitor memory usage as a workaround.

The function, 'monitor_memory_whos.m' operates by using the WHOS command and evaluating it within the 'base' workspace. Each variable's memory usage is summed up and converted into megabytes. This function can be run in the background without displaying data to the MATLAB command prompt. However, the memory usage of the workspace is not the only memory used by MATLAB. Typically, the program starts up using approximately 500 MB of memory.

To run the 'monitor_memory_whos.m' function please type the following the MATLAB command prompt:

A = magic(1000);
B = phantom(500);
C = peaks(250);
in_use = monitor_memory_whos

The memory function can also be used to monitor memory usage on Windows systems. For more information on memory management, please refer to the following link:

https://www.mathworks.com/help/matlab/performance-and-memory.html

Related Solutions

MATLAB: How to find the amount of data generated/memory requirment for a program

Sorry. It is not possible to do these things in general.

MATLAB uses dynamically generated variables and arrays. So the memory required can easily vary according to the inputs of your function. And since temporary variables will be created by functions that are called, they may be arbitrarily large.

Suppose you have a function that calls a function. Down in the depths of one of these sub-functions, it sometimes chooses to call the function perms(1:1000), based perhaps on something unknowable. Or worse, suppose you have code that looks like this:

n = input('what is n?')
str = ['A = perms(1:',num2str(n),');'];
eval(str)

Yes, I know, obscene code. But if someone types in 1000 to that question, the result will be something that will take more space than any computer would have in this universe, even if every single elementary particle in the universe was a byte of RAM. Worse, MATLAB cannot know in advance this would happen. So it cannot look at that code without evaluating it to know ho much memory will be required.

MATLAB: Can I access more than 2GB of memory when running a 32-bit MATLAB 7.5 (2007b) on a Mac

In theory, 32-bit applications can address up to 4GB of virtual memory.

However, a number of things affect the actual memory accessibility:

1. The Operating System reserves memory for itself, reducing the amount of memory its applications can use.

2. Other applications running at the same time can eat up memory as well.

3. MATLAB reserves memory for itself. Even when there is no code running and there are no variables in the workspace, MATLAB is still using memory.

4. The memory available to MATLAB may be fragmented when starting additional tools or toolboxes, or loading MATLAB functions into memory. This limits the size of the largest contiguous block of memory. Since MATLAB matrices need to be stored in contiguous blocks, Out of Memory errors can occur while trying to create a matrix larger than the size of the largest contiguous block, even if that memory exists in several fragmented blocks.

There are tools for memory management for Macs:

The TOP command allows you to view the RPRVT (amount of memory in use) and VSIZE(amount of virtual memory paged so far) for the applications with top CPU usage:

top

To access more memory you can run MATLAB from xterm with –nojvm option:

   matlab –nojvm

which does not load Java Virtual Machine and thus saves memory MATLAB uses for itself otherwise.

For more on Memory Management, please refer to the following Tech Notes:

http://www.mathworks.com/support/tech-notes/1100/1106.html

http://www.mathworks.com/support/tech-notes/1100/1107.html

http://www.mathworks.com/support/tech-notes/1100/1110.html

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Related Solutions

MATLAB: How to find the amount of data generated/memory requirment for a program

MATLAB: Can I access more than 2GB of memory when running a 32-bit MATLAB 7.5 (2007b) on a Mac

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