breaking infinite loops in beanshell scripts

[GoogleCodeExporter]

Find a way to break infinite loops.

Hi,
In our environment we run arbitrary beanshell scripts developed by our 
customers.
If one of the scripts is buggy, it may fall into a infinite loop, which blocks 
our application and make it hang. And ... this will happen because it is 
possible.

So it is critical for us to prevent beanshell scripts from running in an 
infinite loop. 

My first try, to run the script in separate thread, monitored by another 
thread, failed because the new generated thread does not contain all 
threadlocal variables/settings/flags from the main thread.
So I could not do for example EJB calls from the new thread because it was 
instantiated by the other (main) thread. (the script runs in JBOSS 
environment). 

Now I took the source bsh-2.1b6 and had a closer look at it.

Every loop finally breaks down to a if statement that evaluates the condition. 
What I did now was:

- modified Interpreter.java with a methods
 setTimeoutInSeconds() invoked from caller before eval()
 checkTimeoutExpiration()
 setStartTime() called from eval( String statements ) upon invocation

- modified BSHIfStatement.java the evaluateCondition() method calls a 
Interpreter.checkTimeoutExpiration() which looks for the topmost Interpreter 
parent and checks, if the timeout expired, if any was set.
If yes, throw EvalError()

Because it is critical for us to have this under control, we approve the 
minimal perfomance impact.

I described here what I did because I find it important to have this under 
control, to prevent infinite loops. This only works for loops and does not 
break any ongoing input/output operation.

What do you think?
Would it be possible that you assembled a mechanism like this in the beanshell 
source code?
Regards
Hubert

Original issue reported on code.google.com by hugibertus on 9 Feb 2012 at 9:54

[GoogleCodeExporter]

This is a general issue for script languages on the JVM, which are often used 
as you describe.
When I looked at JSR-223 when it was published I was disappointed that this 
issue was not addressed (as many others).
One workaround would be using the Thread interrupt state for this. Then you 
have to start a parallel Thread with is just doing a sleep for the desired 
maximum execution time. The first finished task (sleeping or script execution) 
will then interrupt the Thread of the other task. And in Interpreter the 
interrupt state of the current Thread is checked and if it is set, an 
ExecutionException is thrown.

Downside is that some API fail miserably when threads are interrupted...

Original comment by pejob...@gmail.com on 9 Feb 2012 at 10:42

[GoogleCodeExporter]

It seems issue #76 is for the same feature. Link it here. Let's find a proper 
and common way to achieve this...

Original comment by verilo...@gmail.com on 11 Oct 2012 at 7:32