I use the Groovy Script as a sort of function that returns a specific type and 
call it repeatedly with different bindings, the following is an excerpt of my 
code:

private static final GroovyClassLoader GROOVY_CLASSLOADER = new 
GroovyClassLoader();
private static final Map<String, Script> functionCache = new HashMap<>();

public static MyReturnType evaluate(String functionString, Object myDataToBind) 
{

Script script = null;
          try {
                script = resolveFunction(functionString);
          } catch (Exception e)  {
                throw new IllegalArgumentException("The function could not be 
resolved: " + functionString, e);
          }
          script.getBinding().setVariable(VAR, myDataToBind);
          Object o = null;
          try {
                o = script.run();
          } catch (Exception e) {
                throw new IllegalArgumentException("The function is not valid: 
" + functionString, e);
          }
          MyReturnType ts = null;
          if(o instanceof MyReturnType) {
                ts = (MyReturnType) o;
          } else {
                throw new IllegalArgumentException("The function doesn't 
evaluate to a MyReturnType: " + functionString);
          }

          return ts;

}


Script resolveFunction(String f) throws InstantiationException, 
IllegalAccessException  {
if(functionCache.containsKey(f)) {    // functions are likely repeated many 
times in one chunk
     return functionCache.get(f);
}

     // fiddle a bit with the string representation of the script

Class<?> clazz = GROOVY_CLASSLOADER.parseClass(f);
Object cc = clazz.newInstance();
Script script = (Script) cc;
functionCache.put(f, script);
return script;
}






From: Ralph Johnson [mailto:rjohnson.u...@gmail.com]
Sent: Tuesday, February 13, 2018 3:41 AM
To: users@groovy.apache.org
Subject: Re: Executing Groovy DSL scripts concurrently

That guide to integrating is *very* interesting!   I had never seen 
GroovyClassLoader before.

I work with a large application that uses GroovyShell a lot.  It has thousands 
of scripts.   Sometimes they call each other recursively, which runs into the 
same problem with shared Bindings that concurrency has.    I wondered why a 
script couldn't be a class so that I could instantiate it each time it ran, and 
so not have to share bindings.   I am pretty sure that with GroovyClassLoader, 
I can do it.    Thanks for pointing it out!

-Ralph Johnson

On Mon, Feb 12, 2018 at 2:10 AM, Korbee Reinout 
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Hi,

According to: 
http://docs.groovy-lang.org/latest/html/documentation/guide-integrating.html

“You must be very careful when using shared data in a multithreaded 
environment. The Binding instance that you pass to GroovyShell is not thread 
safe, and shared by all scripts.”

There are some guidelines regarding multi-threading and thread-safety. Before 
attempting something like this, ask yourself the question, “can I guarantee 
that my code is thread safe?”, which is very different from running a 
successful test without concurrency issues.

You could use the GroovyClassLoader directly and keep the compiled scripts in a 
cache, see the mentioned docs on how to obtain thread-safety with the Binding 
object.

From: K Adithyan (tech) [mailto:adi.k....@gmail.com<mailto:adi.k....@gmail.com>]
Sent: Wednesday, February 7, 2018 4:15 PM
To: users@groovy.apache.org<mailto:users@groovy.apache.org>
Subject: Executing Groovy DSL scripts concurrently

Team,

Our application is a Root Cause Analysis Computation Engine for Telecom 
networks. We have been implementing the logics in java only so far.

We are now planning to write DSLs for each feature and write the logics using 
the DSL. We have implemented a framework for plugging in any number of DSLs and 
integrated that DSL Framework with our application.

Each of the logics written over the DSL are executed concurrently using 40 or 
50 or 60 threads based on the rate of the incoming events. Due to the 
concurrency, we are now creating `GroovyShell` object for every execution and 
calling `shell.evaluate(ourScriptFile)` to run the DSL scripts with our own 
Binding object and delegates.

This prevents the system to run the logic at its own speed. Everytime parsing 
and running takes significant time which reduces the event handling capacity of 
the application.

I have attempted with `GroovyShell` and `GroovyScriptEngine`. But both are 
offering same performance levels. GroovyShell is slightly better than 
GroovyScriptEngine.

Under these circumstances, what is the best way to wrap our script logic, that 
is based on our own DSLs, and run it concurrently without any overhead for 
parsing, compilation, etc?????????


Pls advice

Reg,
Adithyan K

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