double-check singleton has been executed TWICE

[alalag1]

Expected behavior

minimize concurrent operations

Actual behavior

double-check singleton has been executed TWICE

esa-restlight/restlight-jaxrs-provider/src/main/java/io/esastack/restlight/jaxrs/configure/LazyInstantiateHandler.java

Lines 49 to 78 in 4f2cb40

	Object getInstanceThenInit() {
	Object instance = getInstance();
	if (!initialized) {
	synchronized (this) {
	if (!initialized) {
	context.handlerFactory().orElseThrow(() ->
	new IllegalStateException("HandlerFactory is not present while initializing object," +
	" clazz: " + clazz))
	.doInit(instance, null);
	initialized = true;
	}
	}
	}
	return instance;
	}
	Object getInstance() {
	if (target != null) {
	return target;
	}
	synchronized (this) {
	if (target == null) {
	target = context.handlerFactory().orElseThrow(() ->
	new IllegalStateException("HandlerFactory is not present while instantiating class: " + clazz))
	.instantiate(clazz, null);
	}
	}
	return target;
	}
	}

Steps to reproduce

Env

• Restlight version: 1.0.0-SNAPSHOT