WITH_THREAD should be kept per Context

[kariya-mitsuru]

Please see the sample code below.

============================== sample code ==============================

import org.graalvm.polyglot.Context;

public class MultiContext1 {
    public static void main(String[] args) {
        try (Context ctx1 = Context.newBuilder("python").build();
             Context ctx2 = Context.newBuilder("python")
                .allowExperimentalOptions(true)
                .option("python.WithThread", "true").build()) {

            System.out.println("initialize start");
            ctx1.eval("python", "import _sysconfig");
            ctx2.eval("python", "import _sysconfig");
            System.out.println("initialize end");

            System.out.println("eval start");
            ctx1.eval("python", "print(_sysconfig.get_config_vars())");
            ctx2.eval("python", "print(_sysconfig.get_config_vars())");
            System.out.println("eval end");
        }
    }
}

============================== sample code ==============================

============================== output ==============================

initialize start
initialize end
eval start
{'WITH_THREAD': 1}
{'WITH_THREAD': 1}
eval end

============================== output ==============================

I think WITH_THREAD should be kept per Context, so the output should look like this.

============================== output ==============================

initialize start
initialize end
eval start
{'WITH_THREAD': 0}
{'WITH_THREAD': 1}
eval end

============================== output ==============================

[timfel]

We are introducing proper threading for the next release, so this option will completely go away

[timfel]

Unfortunately, the threading option cannot be per context in any case. We need to be able to share ASTs across contexts in the same engine, but enabling or disabling threads such a deep impact on the ASTs that they become unshareable between those two scenarios.