Open a console (if the system is not responding, Ctrl+Alt+f1 / Ctrl+Alt+f2  will switch back and forth between graphics mode and text console)

First thing is to find the pid (process id). It appears in red color in the lines below:

To kill a Mistika application, or a render that was  launched in foreground mode (if it was launched in the render panel using the "Foreground" button) execute this:

ps -ef | grep -v grep | grep "mistika.bin"

Which give this kind of output:

mistika  19200     1 43 13:32 pts/4    00:00:00 /home/mistika/MISTIKA-ENV/bin/mistika.bin

For renders in backgorund mode (all other render cases) , add the "-r" parameter to the mistika command, as follows:

ps -ef | grep -v grep | grep "mistika.bin -r"

Which give this kind of output:

mistika  19208     1 43 13:52 pts/4    00:00:00 /home/mistika/MISTIKA-ENV/bin/mistika.bin -r /MISTIKA_PROJECTS/myproject/DATA/RENDER/myrendername/mayrendername.rnd

Using that method you can also see the render name in the line, so if there are more instances of mistika you can be sure that you are killing the pid of the right line.

Then kill it with no mercy:

The pid is the second number in that lines, 19208 in the last example. Then

kill-9 19208

Then press Ctrl+ F1 to come back to the graphics mode (that is for CentOS,  for the case of Suse use Ctrl + Alt + F7 )


A faster trick is to use this command:  

killall -9 mistika.bin   

But in that way you don't distinguish between renders and mistika sessions, so all will die...

If nothing works, you could try Ctrl + Alt + Backspace, which also kills the X session.