Re: 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.farb...@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