Script evaluation in a separated thread

[mathiasd]

Hi,
Is it possible to run script evaluations in a separated thread ? I made my own script engine which uses the javascript engine.
I have something like that :

public Object eval(String script, Bindings n) throws ScriptException {
        ScriptThread thread = new ScriptThread(javascriptEngine,script,n);
        thread.start();
        long startTime = System.currentTimeMillis();
        while(System.currentTimeMillis()-startTime < 10000 && thread.getResult() == null);
        Object result = thread.getResult();
        if(result == null) {
            throw new ScriptException("Script execution was too long");
        }
        return result;
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And the scriptThread is simply :

@Override
    public void run() {
        try {
            result = engine.eval(script, bindings);
        } catch (ScriptException e) {
            e.printStackTrace();
        }
    }
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But when I run this code I have :

Exception in thread "Thread-2" java.lang.NullPointerException
   at org.activiti.engine.impl.scripting.BeansResolverFactory.containsKey(BeansResolverFactory.java:30)
   at org.activiti.engine.impl.scripting.ScriptBindings.containsKey(ScriptBindings.java:52)
   at javax.script.SimpleScriptContext.getAttributesScope(Unknown Source)
   at com.sun.script.javascript.ExternalScriptable.put(Unknown Source)
   at com.sun.script.javascript.RhinoScriptEngine.getRuntimeScope(Unknown Source)
   at com.sun.script.javascript.RhinoScriptEngine.eval(Unknown Source)
   at com.sun.script.javascript.RhinoScriptEngine.eval(Unknown Source)
   at javax.script.AbstractScriptEngine.eval(Unknown Source)
   at xxx.ScriptThread.run(ScriptThread.java:23)
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The line where the exception is thrown is (in BeansResolverFactory.java:30) :

return Context.getProcessEngineConfiguration().getBeans().containsKey(key);
‍‍‍

And this is "Context.getProcessEngineConfiguration()" which returns "null". Here's the code of this part in 'Context.java:38' :

public static ProcessEngineConfigurationImpl getProcessEngineConfiguration() {
     Stack<ProcessEngineConfigurationImpl> stack = getStack(processEngineConfigurationStackThreadLocal);
    if (stack.isEmpty()) {
      return null;
    }
    return stack.peek();
}
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Do you have any idea to perform this ?

[trademak]

Hi,

In the current trunk of Activiti you can make use of async continuations.
This means that you can execute a specific task asynchronous. Is that what you're looking for?

Best regards,

[mathiasd]

Not sure. Actually I'm trying to add some protections in my workflows.
For example I want to protect my workflow engine against infinite loops in script tasks. That's why I want to start the eval method in a separated Thread and interrupt this Thread if the evaluation is too long.

Actually I found the problem, I just add :

Context.setProcessEngineConfiguration(config);
Context.setCommandContext(commandContext);
before evaluation. Now I throw a ScriptException if the script is too long. My new problem () is that after the exception is thrown, the script seems to be still running (JavaVM still take 100% of the CPU).

Maybe you know a better solution to implement this "watchdog" ?