I am using matlab to automatically parameter and launch a finite element method code. I write a parameter text file that the FEM code will read, and then call for the FEM code with :
[status,cmdout]=system(['FEMApp ' current_folder '\MyFile']);
Sometimes, the FEM App will be unable to complete its task, and send an error message in the command window. Until now, I was able to detect the error message in cmdout, and proceed to the next paramter set.
For an unknown reason, the system command started to behave differently : it gets stuck for seemingly forever (Matlab is always in "busy" mode). Did I change anything without realizing it ?
For now, I am using the following solution :
[status,cmdout]=system(['FEMApp ' current_folder '\MyFile &']);
pause(45)
system(['taskkill' 'FEMProcessus')
It works correctly, but it slows my computation a lot (~ x5), because Matlab will always wait 45 secondes even when the task is completed in much less time.
Can anyone explain the change in behaviour of Matlab ?
Does anyone has a cleverer work around than mine ?
It should be noted that Matlab is an interpreter rather than a compiler. That means it performs a lot of internal operations, hidden from the developer, some of which may require a lot of CPU resources. Finite Element applications are very numerically intense in terms of using CPU and RAM resources. It might not be a good idea to use Matlab for FEM programming. Try to use some numerically-oriented language, like C or Fortran, where you will have full control over memory allocation and arithmetic operations.
I am batch processing a bunch of files (~200) on MATLAB, in essence
for i = 1:n, process(i); end
where process(i) opens a file, reads it and writes out the output to another file. (I am not posting details about process here because it is hundreds of lines long and I readily admit I don't fully understand the code, having obtained it from someone else).
This runs out of memory after every dozen of files or so. Of course, on Linux, the memory function is not available so we have to figure it out "by hand". Well, I thought there is some memory leak, so let's issue a clear all after every run, i.e.
for i = 1:n, process(i); clear all; end
No luck, this still runs out of memory. At the point where this happens, who says there's just two small arrays in memory (<100 elements). Note that quitting MATLAB and restarting solves the problem, so the computer certainly has enough memory to process a single item.
Any ideas to help me detect where the error comes from would be welcome.
This is probable not the solution you are hoping for but as a workaround you could have a shell script that loops over several calls to Matlab.
I create a GUI that use Parallel computing for accelerating Neural network and SVM models. When I enable Parallel computing in my GUI all thing (MATLAB,My GUI and my code's window) will freeze and I can't maximize these windows either, but my program is working,using workers and sometimes I can see updates in graphs and values of GUI. When I disable Parallel computing in my program everything is normal. In first situation sometimes my GUI turns to black color (Background of GUI,buttons,text-boxes and edit-boxes are good) but values are updating in iterations of created GUI.
What is this problem?
Thanks.
Sorry for the late answer. It is hard to give a definite answer to a solution here. The problem is quite advanced and most of the code we cannot do anthing about. What happens in parfor is probably that matlab puts some kind of lock (mutex or something else) on the elements it accesses at the moment. Also, since parfor works in parallel it is unlikely that any of the data in the loop is ever untouched. The only solution I can see is that you run shorter processes. That will allow your gui to update between the prcesses.
It would probably work to put a drawnow where you want the gui to update.
Other options could also be to place the gui in a location where you does not need to move it or dock it to the main window in matlab. But these are shortcuts which will only hide the problem.
This question already has an answer here:
How to abort a running program in MATLAB?
(1 answer)
Closed 7 years ago.
I write a long running script in Matlab, e.g.
tic;
d = rand(5000);
[a,b,c] = svd(d);
toc;
It seems running forever. Becasue I press F5 in the editor window. So I cannot press C-Break to stop in the Matlab console.
I just want to know how to stop the script. I am current use Task Manager to kill Matlab, which is really silly.
Thanks.
Matlab help says this-
For M-files that run a long time, or that call built-ins or MEX-files that run a long time, Ctrl+C does not always effectively stop execution. Typically, this happens on Microsoft Windows platforms rather than UNIX[1] platforms. If you experience this problem, you can help MATLAB break execution by including a drawnow, pause, or getframe function in your M-file, for example, within a large loop. Note that Ctrl+C might be less responsive if you started MATLAB with the -nodesktop option.
So I don't think any option exist. This happens with many matlab functions that are complex. Either we have to wait or don't use them!.
If ctrl+c doesn't respond right away because your script is too long/complex, hold it.
The break command doesn't run when matlab is executing some of its deeper scripts, and either it won't log a ctrl sequence in the buffer, or it clears the buffer just before or just after it completes those pieces of code. In either case, when matlab returns to execute more of your script, it will recognize that you are holding ctrl+c and terminate.
For longer running programs, I usually try to find a good place to provide a status update and I always accompany that with some measure of time using tic and toc. Depending on what I am doing, I might use run time, segment time, some kind of average, etc...
For really long running programs, I found this to be exceptionally useful
http://www.mathworks.com/matlabcentral/fileexchange/16649-send-text-message-to-cell-phone/content/send_text_message.m
but it looks like they have some newer functions for this too.
MATLAB doesn't respond to Ctrl-C while executing a mex implemented function such as svd. Also when MATLAB is allocating big chunk of memory it doesn't respond. A good practice is to always run your functions for small amount of data, and when all test passes run it for actual scale. When time is an issue, you would want to analyze how much time each segment of code runs as well as their rough time complexity.
Consider having multiple matlab sessions. Keep the main session window (the pretty one with all the colours, file manager, command history, workspace, editor etc.) for running stuff that you know will terminate.
Stuff that you are experimenting with, say you are messing with ode suite and you get lots of warnings: matrix singular, because you altered some parameter and didn't predict what would happen, run in a separate session:
dos('matlab -automation -r &')
You can kill that without having to restart the whole of Matlab.
One solution I adopted--for use with java code, but the concept is the same with mexFunctions, just messier--is to return a FutureValue and then loop while FutureValue.finished() or whatever returns true. The actual code executes in another thread/process. Wrapping a try,catch around that and a FutureValue.cancel() in the catch block works for me.
In the case of mex functions, you will need to return somesort of pointer (as an int) that points to a struct/object that has all the data you need (native thread handler, bool for complete etc). In the case of a built in mexFunction, your mexFunction will most likely need to call that mexFunction in the separate thread. Mex functions are just DLLs/shared objects after all.
PseudoCode
FV = mexLongProcessInAnotherThread();
try
while ~mexIsDone(FV);
java.lang.Thread.sleep(100); %pause has a memory leak
drawnow; %allow stdout/err from mex to display in command window
end
catch
mexCancel(FV);
end
Since you mentioned Task Manager, I'll guess you're using Windows. Assuming you're running your script within the editor, if you aren't opposed to quitting the editor at the same time as quitting the running program, the keyboard shortcut to end a process is:
Alt + F4
(By which I mean press the 'Alt' and 'F4' keys on your keyboard simultaneously.)
Alternatively, as mentioned in other answers,
Ctrl + C
should also work, but will not quit the editor.
if you are running your matlab on linux, you can terminate the matlab by command in linux consule.
first you should find the PID number of matlab by this code:
top
then you can use this code to kill matlab:
kill
example:
kill 58056
To add on:
you can insert a time check within a loop with intensive or possible deadlock, ie.
:
section_toc_conditionalBreakOff;
:
where within this section
if (toc > timeRequiredToBreakOff) % time conditional break off
return;
% other options may be:
% 1. display intermediate values with pause;
% 2. exit; % in some cases, extreme : kill/ quit matlab
end
Is there a way to end a matlab process that is taking too long to run?
ctrl+alt+delete is all I know right now and that shuts downt he program entirely.
It's Ctrl+C.
Apparently it's inconsistent at times:
http://www.mathworks.com/support/solutions/en/data/1-188VX/
Control C is the answer. It will break in. However, there are cases where it still may take a while to do the interrupt. For example, if the process is trying to solve a huge linear system of equations or allocate a huge block of virtual memory, then matlab will not see the interrupt until the solver returns control to matlab itself. So it may take a while before the break happens. If this is just a long running iterative process, then the break will happen quickly.