setNashornGlobal usage

[Jim Laskey (Oracle)]

Tobias,

We'll look into removing the doPrivileged on first entry (security is checked elsewhere), but we need to do a security assessment before proceeding.

That said, I would recommend as a best practice to use a per-thread JavaScript loop instead, to avoid such issues.  I generally use a java.util.concurrent.LinkedBlockingQueue to "feed" the loop from other threads.

Cheers,

-- Jim




On 2013-07-17, at 12:37 PM, Tobias Schlottke <tobias.schlottke at gmail.com> wrote:

> Hi there,
> 
> I've built a small case where I evaluate a compiled script equipped with a custom bindings.
> The script is equipped with some variables and and compiled like this:
> 
>      engine.put("shopId", "test");
>      runner = (Bindings) engine.compile(ad.getCondition_script().getCode()).eval();
> 
> afterwards, I execute the "run" method on the object returned by eval() like this:
> 
>    return (MyCustomObject) engine.invokeMethod(runner, "run", attr);
> 
> the run method does local compilations but does not change anything so basically the runner is immutable.
> I access it from various threads.
> 
> When profiling the code I see a lot of time spent in java.security.AccessController.doPrivileged() which is invoked in setNashornGlobal() if the globals changed.
> I'm a bit unsure what changed globals really mean because in my case nothing (either context nor bindings) changed and I wonder if it is necessary.
> 
> Best,
> 
> Tobias