nashorn CompiledScript graalvm equivalent - graalvm

Question

I have a fairly big file that needs to often be evaluated,
with nashorn I used to do something like that :
CompiledScript compiledScript = ((Compilable) engine).compile(text);
and later on, I could call many times the following :
Context context = new SimpleScriptContext();
compiledScript.eval(context);
this was quite fast.
Using the new Polyglot API, I do :
Source source = Source.newBuilder("js", myFile).build();
then :
Context context = Context.newBuilder("js").option("js.nashorn-compat", "true").build();
context.eval(source)
Using jmh, I have a big performance difference between the two
Benchmark Mode Cnt Score Error Units
JmhBenchmark.testEvalGraal avgt 5 42,855 ± 11,118 ms/op
JmhBenchmark.testEvalNashorn avgt 5 2,739 ± 1,101 ms/op
If I do the eval on the same context, it is working properly, but I don't want to have a shared context between two consecutive eval (unless the concept of Context of Graal is not the same as the one from Nashorn).

Answer 1

To reproduce your ScriptEngine setup with GraalVM, you should re-use the same Engine (org.graalvm.polyglot.Engine) and .close() the context after use:
Source source = Source.newBuilder("js", myFile).build();
Engine engine = Engine.create();
and later:
Context context = Context.newBuilder("js")
.engine(engine)
.option("js.nashorn-compat", "true").build();
context.eval(source);
context.close();
Quoting the Context.Builder.engine documentation:
Explicitly sets the underlying engine to use. By default, every context has its own isolated engine. If multiple contexts are created from one engine, then they may share/cache certain system resources like ASTs or optimized code by specifying a single underlying engine.