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Matlab timeouts
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Dustin
Mar 27, 2014, 2:59:10 AM3/27/14
to
Hi,
I am trying to time out a MATLAB function that may or may not take too long to execute. I am able to use timers to throw errors, but they do not appear to be in a form that can be caught within a try-catch block. As an example, the code that I am using is:
function tmptimer(time_out)
t = timer('TimerFcn', 'error(''timeout'')', 'StartDelay', time_out);
start(t);
try
input('Waiting to timeout'); % Example. Can be an arbitrary function
catch
fprintf('Caught the error');
delete(t);
end
end
The output by running something like tmptimer(1) is:
Waiting to timeout??? Error while evaluating TimerFcn for timer 'timer-49'
timeout
However, the error does not stop execution! In other words, the command window still keeps waiting for the input in this particular case. Only when I do a Ctrl+C, do I get:
??? Operation terminated by user during ==> tmptimer at 7
Can anyone tell me how I can generate an error that can be picked up by a try-catch block or if there is any other way at all to time out an arbitrary function call?
Thanks
I am trying to time out a MATLAB function that may or may not take too long to execute. I am able to use timers to throw errors, but they do not appear to be in a form that can be caught within a try-catch block. As an example, the code that I am using is:
function tmptimer(time_out)
t = timer('TimerFcn', 'error(''timeout'')', 'StartDelay', time_out);
start(t);
try
input('Waiting to timeout'); % Example. Can be an arbitrary function
catch
fprintf('Caught the error');
delete(t);
end
end
The output by running something like tmptimer(1) is:
Waiting to timeout??? Error while evaluating TimerFcn for timer 'timer-49'
timeout
However, the error does not stop execution! In other words, the command window still keeps waiting for the input in this particular case. Only when I do a Ctrl+C, do I get:
??? Operation terminated by user during ==> tmptimer at 7
Can anyone tell me how I can generate an error that can be picked up by a try-catch block or if there is any other way at all to time out an arbitrary function call?
Thanks
Steven Lord
Mar 27, 2014, 9:35:39 AM3/27/14
to
"Dustin " <gol...@mailinator.com> wrote in message
news:lh0i7u$sfr$1...@newscl01ah.mathworks.com...
function call (short of killing MATLAB or _maybe_ on Linux sending SIGINT to
the MATLAB process. I haven't tried the latter, but I have done the former.)
For specific functions, you could have the TimerFcn of a timer set some
application data (SETAPPDATA) that the function queries (with GETAPPDATA)
periodically; if the application data says to stop, the function could then
stop.
--
Steve Lord
sl...@mathworks.com
To contact Technical Support use the Contact Us link on
http://www.mathworks.com
Dustin
Mar 27, 2014, 10:08:08 AM3/27/14
to
"Steven Lord" <Steve...@mathworks.com> wrote in message <lh19fb$p8m$1...@newscl01ah.mathworks.com>...
I spent a few hours working on this, but in the end went with a supervisor in Linux that restarts the process if it doesn't respond with the output of the function within a set amount of time. It's better than killing from within MATLAB I think, because in extreme CPU cases like a blank "while true" loop, MATLAB seems to be blocking TimerFcn from executing until the loop is somehow exited.
>
> In general? No, I don't believe there is a way to time out an arbitrary
> function call (short of killing MATLAB or _maybe_ on Linux sending SIGINT to
> the MATLAB process. I haven't tried the latter, but I have done the former.)
>
> For specific functions, you could have the TimerFcn of a timer set some
> application data (SETAPPDATA) that the function queries (with GETAPPDATA)
> periodically; if the application data says to stop, the function could then
> stop.
>
Thanks, Steve. The app data idea is good, except that I am worried about getting stuck in certain subfunctions of the main function (working with videos, so can take some time depending on video size) which I do not control and hence, would not be able to query the app data.
> In general? No, I don't believe there is a way to time out an arbitrary
> function call (short of killing MATLAB or _maybe_ on Linux sending SIGINT to
> the MATLAB process. I haven't tried the latter, but I have done the former.)
>
> For specific functions, you could have the TimerFcn of a timer set some
> application data (SETAPPDATA) that the function queries (with GETAPPDATA)
> periodically; if the application data says to stop, the function could then
> stop.
>
I spent a few hours working on this, but in the end went with a supervisor in Linux that restarts the process if it doesn't respond with the output of the function within a set amount of time. It's better than killing from within MATLAB I think, because in extreme CPU cases like a blank "while true" loop, MATLAB seems to be blocking TimerFcn from executing until the loop is somehow exited.
Alexey
Mar 27, 2014, 11:47:08 AM3/27/14
to
To terminate an arbitrary function you need to run it as a separate thread (a process), that the main process can monitor and if necessary terminate the thread. I have no idea if it is possible in Matlab.
A possible way could be to implement the termination within you function.
To do this you can use an event function.
I just answered a similar question here
http://www.mathworks.de/matlabcentral/newsreader/view_thread/119565
Best
Alex
"Dustin" wrote in message <lh1bc8$1m9$1...@newscl01ah.mathworks.com>...
A possible way could be to implement the termination within you function.
To do this you can use an event function.
I just answered a similar question here
http://www.mathworks.de/matlabcentral/newsreader/view_thread/119565
Best
Alex
"Dustin" wrote in message <lh1bc8$1m9$1...@newscl01ah.mathworks.com>...
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