P-Code Generation Segmentation Fault

Hello!

I am running a script to recursively generate p-code. This has been working fine up until 2012a, but now it gives a segmentation fault on a single specific file every time I try to run it for a certain application.

Is there something that I need to update along with MATLAB? What could cause this?

Thanks

Answer 1

[Sean de Wolski]

Please contact MathWorks' Technical Support

Answer 2

[Frank Drop]

I am having exactly the same issues. I am recursively walking through a number of folders and pcode'ing their content. The first run works, the second time I run the code (within a MATLAB session) I get a segmentation error. After restarting MATLAB I can run the code once, and then I get a segmentation error again.

[Sean de Wolski]

Frank, what is the result of the following after the first run?

op = fopen('all')

If anything is open, if you

fclose all

Does the crash still happen?

Answer 3

[Frank Drop]

After I run the recursive function I do op = fopen('all') which gives an empty array as result:

 op = 

    []

Then before rerunning I do

   fclose all

But the problem persist.

I did some more tests with the function. Basic functionality is:

 function recursivePCode(sourceFolder,destinationFolder)
   cd(destinationFolder); % The function moves to the folder where the p code should reside.
   pcode(sourceFolder);   % Creates the p functions and stores it in destinationFolder

   for all subfolders in destinationFolder
    recursivePCode(sourceFolder/subfolder_n,destinationFolder/subfolder_n);
   end
 end

Now, if I run:

 recursivePCode('D:\sourceFolder','D:\destinationFolder');
 recursivePCode('D:\sourceFolder','D:\destinationFolder');
 recursivePCode('D:\sourceFolder','D:\destinationFolder');

It will give a segmentation error during the second recursivePCode call. However, if I run...

 recursivePCode('D:\sourceFolder','D:\destinationFolder1');
 recursivePCode('D:\sourceFolder','D:\destinationFolder2');
 recursivePCode('D:\sourceFolder','D:\destinationFolder3');

... all is fine. It seems overwriting the existing pcode is the problem. So now I attempt to delete the existing p-files in the destination folder before running pcode(), but the problem still persists.

The pcode function appears to crash on p-coding a classdef folder called '@CacheProcessData5'.

[Sean de Wolski]

Is there an instance of that class loaded in the MATLAB workspace?

[Frank Drop]

It appears that I had a bug in the code that would delete the existing files in the destinationFolder, now that I fixed that, the segmentation error disappeared. So, cleaning up the destination folder before running pcode seems to resolve the problems. Will report if the problem comes back at a later stage.

Thanks for your comments.

[Frank Drop]

Btw, no, there was no instance of the class loaded in the workspace. Also, before running the function I clear all classes with

 clear classes

[Sean de Wolski]

If you can create a minimal working example, please send it to MathWorks Tech Support so that they can pass it along to development. Unless it's in a custom MEX file, a bug in your code should not cause a segv.

[Frank Drop]

I just tried reproducing the problem, but even without deleting the files in the destination folder, the problem does not arise anymore.

I am guessing now that it (also) had something to do with the fact that the destination folder is a shared network folder (shared in the windows network) and perhaps other PCs had a lock on this folder or something like that? If the problem comes back I will post again.

Are segmentation errors more likely on old installations or perhaps sensitive to updates to the JVM? I've once ran into segmentation errors all of a sudden (no change to the matlab code) when I first ran the particular code on a certain morning (java updates are automatically installed here at work during night time). I traced this segmentation error down to a

 load('somematfile.mat')

statement, which would load a variable 'd' to the function workspace, after which the function would operate on d. The segmentation error disappeared after adding

 d = [];

on the line before the load statement.