MATLAB Answers


memory leak using activex to save multiple excel files

Asked by Rhys
on 30 Nov 2012

I have been trying to make a code that will save 1000's of excel files containing data analysed from csv files. I have a base excel file I write the data to, run several macros to make charts etc and then I save the file. I then make a copy of the file (which I store away) and I clear the data in my base excel file by running a macro called 'cleanup' so I'm ready to repeat these steps with the next set of data. I have done it this way to avoid opening and closing connections all over the place in order to make things run faster. However there appears to be a memory leak and although things start off fast the code eventually slows to a crawl as excel starts to hog well over a GB of memory. Is there a way to stop the memory build up in excel - there should only ever be the one connection so I don't understand how it uses an increasing amount of memory. (edit: the individual files made are fairly small ~ 1MB)


The initial connection is set up as:

if true
e = actxserver ('Excel.Application');
set(e, 'Visible', 0);

and for every file the following is called:

if true
function excelwrite( file , data , macro , macroName , e)
% write data to the excel file      
[m,n] = size(data);
range = '';
%calcrange is borrowed from 'xlswrite'.
range = calcrange(range,m,n);
% if macro is set to 1 then run the macros in the array: 'macroName'
if macro == 1
  for i = 1:length(macroName(:,1))
%save, make a copy, and delete data from active workbook.


Jan Simon
on 3 Dec 2012

The "if true" is useless. I suggest to omit it, when you post code in a forum.

Are you sure that Matlab occupies the memory? Or could it be Excel, which does not cleanup as wanted? In the later case, an Excel forum would be a better location to ask.

on 4 Dec 2012

Thanks for taking a look. It is indeed the Excel application that can be seen to use increasingly large amounts of memory even though the amount of data in the file doesn't increase. I was just wondering if this was a known issue with using ActiveX within from Matlab or if there was something obviously wrong with the code that I am not spotting. I'll try and look into the Excel part of it more.


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1 Answer

Answer by Mark Whirdy
on 4 Dec 2012

are you not closing the workbooks?


That would certainly cause the problem!

on 6 Dec 2012

There is only ever one workbook open and I keep it open for the duration of the program. I perform a process along the lines of: write data to the open workbook, save the workbook, make copy of the excel file (that gets kept for later), clear the workbook (via a macro), write new data to the workbook, save it, and so on. In task manager you can see that the memory being used by the instance of Excel keeps on increasing. I have had a look on some Excel forums and found a few similar issues, but no definitive solutions. Currently I have "fixed" the issue by periodically closing and reopening the excel file with activex after every 100 writes. This is a bit of a fudge, but gives me the speed increase of not opening and closing the workbook constantly whilst not killing my computer with memory issues.

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