A question about Nashorn and Netbeans debugger

[Sundararajan Athijegannathan]

I reproduced it with NetBeans 8.1 as well and filed a bug: 
https://netbeans.org/bugzilla/show_bug.cgi?id=256771

Again, the workaround (to put bkpt in Java "eval" call and repeated F7) 
works with NetBeans 8.1 as well.

Thanks,
-Sundar

On 11/25/2015 11:27 AM, Sundararajan Athijegannathan wrote:
> Hi Dina,
>
> I used NetBeans 8.0.2 and jdk 8 update 65 on Windows 7.  I think I 
> managed to reproduce the issue you described.
> Steps I used are as follows:
>
> 1) create a new NB project called "script_sample" with one Main.java 
> in it as source:
>
> import javax.script.*;
>
> public class Main {
>    public static void main(String[] args) throws Exception {
>        ScriptEngineManager m = new ScriptEngineManager();
>        ScriptEngine e = m.getEngineByName("nashorn");
>        e.eval("load(\"" + args[0] + "\")");
>        System.out.println("press any key to continue..");
>        System.in.read();
>        e.eval("load(\"" + args[0] + "\")");
>    }
> }
>
> 2) "clean and build" the NB project
>
> 3) create a simple script test.js with the following content (outside 
> the NB project)
>
> print("in test.js script");
> var x = 33;
> x++;
> print(x);
>
> 3) in a command line shell (I used cygwin), start the java process 
> with debugger server on - but not suspended at the start:
>
>      java -cp script_sample/dist/script_sample.jar 
> -agentlib:jdwp=server=y,suspend=n,transport=dt_socket Main test.js
>
> The last command runs code up to the point of System.in.read call in 
> Main.java
>
> 4) In NetBeans, open the test script file "test.js" and set breakpoint 
> @ "print" call.
>
> 5) In NetBeans, use "Debug->Attach Debugger..." menu and specify the 
> socket port printed by step (3)
>
> 5) enter a value for System.in.read() in command line shell.
>
> 6) No breakpoint hit @ test.js
>
> But, if step (3) was modified to suspend process at start for debugger 
> attach:
>
>      java -cp script_sample/dist/script_sample.jar 
> -agentlib:jdwp=server=y,suspend=y,transport=dt_socket Main test.js
>
> The breakpoint in test.js enters (twice) once for each 
> "load("test.js")" call.
>
> So, there seems to be a bug somewhere (in NetBeans?). That said, there 
> seems to be a simple workaround for this issue.
> Within NB, set a breakpoint in Main.java (in addition to breakpoint in 
> test.js) at second eval call  (line 10).  breakpoint is hit in Main.java.
> At that point, keep hitting "Step Into" (F7) menu. It eventually lands 
> in test.js -- and stops at the breakpoint in script!
>
> Hope this helps,
> -Sundar
>
> On 11/24/2015 10:00 PM, Jim Laskey (Oracle) wrote:
>> Dian,
>>
>> We’ll dive in for you, but the debugger expert (Sunder) will be 
>> signing off soon.  He’ll pick it up tomorrow.
>>
>> Cheers,
>>
>> - Jim
>>
>>
>>
>>> On Nov 24, 2015, at 12:03 PM, Dina Farbman 
>>> <dina.farbman at new-proimage.com> wrote:
>>>
>>> Hi nashorn-dev,
>>> I'm relatively new to Nashorn.
>>> I work on a java 8 application that needs to run server side 
>>> javascript scripts using Nashorn. The java code runs the scripts at 
>>> certain points using nashorn's eval function, like this:
>>>
>>> SimpleBindings simpleBinding= new SimpleBindings();
>>>               simpleBinding.put(....);
>>> ...
>>> ScriptEngineManager factory = new ScriptEngineManager();
>>>             engine = factory.getEngineByName("nashorn");
>>> engine.eval("load('"+scriptpath+"');", simpleBinding);
>>>
>>> In addition, I need to provide a way to debug those scripts.
>>> The only option I could find was using Netbeans debugger (remote 
>>> attach).
>>> The scripts work fine.
>>> The debugger, though, fails to stop at the breakpoints inside the 
>>> scripts in the following scenario:
>>> 1-        Server started
>>> 2-        The script is running once
>>> 3-        Open Netbeans, attach remote debugger
>>> 4-        Run script again
>>>
>>> It will stop at the breakpoints inside the scripts in the following 
>>> scenario:
>>> 1-        Server started
>>> 2-        Open Netbeans, attach remote debugger
>>> 3-        Run the script
>>>
>>> So, what am I doing wrong?
>>> What can cause such behavior?
>>> Is there a reasonable workaround?
>>>
>>> Thanks in advance,
>>> Dina
>