thread([&](){
        //std::lock_guard<mutex> l(jni_mutex);
        debug("%@ %@ %@ %i", java_vm, jni_env, core_class, callback);
        debug("callback: %s   :   %s", callback, cbid);
        try {
            return;
            java_vm->AttachCurrentThread(&jni_env, NULL);
            jmethodID method = android::jni_env->GetStaticMethodID(android::core_class, "callback", "(II)V");
            jni_env->CallStaticVoidMethod(core_class, method, callback, cbid);
            java_vm->DetachCurrentThread();
        } catch(std::exception &e) {
            debug("android callback %s", e.what());
        }
    }).detach();