osgi - OSGi DS 原型参考未发布
问题描述
我在 Liferay 7/DXP 或 osgi 6 上下文中创建了一个简单的 vaadin portlet，我注意到如果我使用具有原型范围的 osgi 声明性服务，我的引用不会被垃圾收集，但如果我使用 serviceObjects，它们会这样做。为什么？
注意：我已经更新了这个问题，并在最后放了一个更简单的例子。
我的主要组件是一个原型组件，它具有对对象的原型引用。如果我使用 osgi 声明式服务来声明我的依赖项（以下清单中的 HelloPresenter），那么我的依赖项将不会被释放并永远留在堆中：
import com.vaadin.server.VaadinRequest;
import com.vaadin.ui.UI;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Reference;
import org.osgi.service.component.annotations.ReferenceScope;
import org.osgi.service.component.annotations.ServiceScope;
/**
* Created by marcel
*/
@Component(
property = {
"com.liferay.portlet.display-category=VaadinHelloMvp",
"javax.portlet.display-name=VaadinHelloMvp",
"javax.portlet.name=VaadinHelloMvp",
"com.vaadin.osgi.liferay.portlet-ui=true"
},
service = UI.class,
scope = ServiceScope.PROTOTYPE
)
public class VaadinHelloMvpPortlet extends UI {
@Reference(scope = ReferenceScope.PROTOTYPE_REQUIRED)
private HelloPresenter helloPresenter;
@Override
protected void init(VaadinRequest request) {
this.setContent(helloPresenter.getViewComponent());
}
}
因此，我尝试以编程方式为我的 HelloPresenter 获取服务实例，这很好用：
import com.vaadin.server.VaadinRequest;
import com.vaadin.ui.UI;
import org.osgi.framework.Bundle;
import org.osgi.framework.FrameworkUtil;
import org.osgi.framework.ServiceObjects;
import org.osgi.framework.ServiceReference;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.ServiceScope;
/**
* Created by marcel
*/
@Component(
property = {
"com.liferay.portlet.display-category=VaadinHelloMvp",
"javax.portlet.display-name=VaadinHelloMvp",
"javax.portlet.name=VaadinHelloMvp",
"com.vaadin.osgi.liferay.portlet-ui=true"
},
service = UI.class,
scope = ServiceScope.PROTOTYPE
)
public class VaadinHelloMvpPortlet extends UI {
private HelloPresenter helloPresenter;
@Override
protected void init(VaadinRequest request) {
Bundle bundle = FrameworkUtil.getBundle(HelloPresenter.class);
ServiceReference<HelloPresenter> serviceReference = bundle.getBundleContext().getServiceReference(HelloPresenter.class);
ServiceObjects<HelloPresenter> serviceObjects = bundle.getBundleContext().getServiceObjects(serviceReference);
helloPresenter = serviceObjects.getService();
this.addDetachListener(event -> serviceObjects.ungetService(helloPresenter));
helloPresenter.init();
this.setContent(helloPresenter.getViewComponent());
}
}
所以我想知道为什么我的 HelloPresenter 在第一种情况下不会被 osgi 框架释放，但在第二种情况下会释放？
我的 portlet (UI) 对象也是用
serviceObjects.getService();
并发布
serviceObjects.ungetService(uiObject);
我尝试了其他场景，在我的 HelloPresenter 中设置了另一个原型引用，这也会产生一个不会被释放和垃圾收集的引用。所以我的经验是，每当您创建一个包含原型引用的服务对象时，在释放服务对象后，该引用不会被释放并卡在 jvm 堆中
所以我的想法是，要么我做错了什么，要么错过了一个参数，这使得我的原型参考永远不会被释放，或者混合 osgi 声明式服务和 serviceObjects 有问题......
你知道我怎样才能让我的第一个例子工作吗？我想使用注释并确保它们在关闭我的 portlet ui 后成为垃圾收集器。
更新
我创建了一个更多示例，其中包含一个单例组件来执行 gogo shell 命令和一个原型对象，该对象还包含一个原型引用：
@Component(
service = GogoShellService.class,
scope = ServiceScope.SINGLETON,
immediate = true,
property =
{
"osgi.command.scope=test",
"osgi.command.function=atest",
}
)
public class GogoShellService {
public String atest() {
Bundle bundle = FrameworkUtil.getBundle(APrototypeComponent.class);
ServiceReference<APrototypeComponent> serviceReference = bundle.getBundleContext().getServiceReference(APrototypeComponent.class);
ServiceObjects<APrototypeComponent> serviceObjects = bundle.getBundleContext().getServiceObjects(serviceReference);
APrototypeComponent service = serviceObjects.getService();
String s = "Hello From: " + service.sayHello();
serviceObjects.ungetService(service);
return s;
}
}
@Component(scope = ServiceScope.PROTOTYPE, service = APrototypeComponent.class, servicefactory = true)
public class APrototypeComponent {
@Reference(scope = ReferenceScope.PROTOTYPE_REQUIRED)
AProInAProComp aProInAProComp;
public String sayHello() {
String hello = "Hello From " + this.getClass().getSimpleName() + "(" + this.toString() + ") ";
if (aProInAProComp != null) {
hello += aProInAProComp.sayHello();
}
return hello;
}
}
@Component(scope = ServiceScope.PROTOTYPE, service = AProInAProComp.class)
public class AProInAProComp {
public String sayHello() {
return "Hello From " + this.getClass().getSimpleName() + "(" + this.toString() + ")";
}
}
每次我执行命令（GogoShellService#atest）时，都会创建一个新的原型实例，之后也应该将其销毁，但我仍然可以在我的堆中看到这个对象，并且运行垃圾收集并没有清理它......
osgi 调试输出如下：
[org_apache_felix_scr:94] getService {de.foo.bar.bax.gogo.GogoShellService}={osgi.command.function=atest, component.name=de.foo.bar.bax.gogo.GogoShellService, component.id=2944, osgi.command.scope=test, service.id=7827, service.bundleid=51, service.scope=bundle}: stack of references: []
APrototypeComponent(2942)] ServiceFactory.getService()
AProInAProComp(2941)] ServiceFactory.getService()
AProInAProComp(2941)] This thread collected dependencies
AProInAProComp(2941)] getService (ServiceFactory) dependencies collected.
AProInAProComp(2941)] Querying state active
AProInAProComp(2941)] Changed state from active to active
APrototypeComponent(2942)] This thread collected dependencies
APrototypeComponent(2942)] getService (ServiceFactory) dependencies collected.
APrototypeComponent(2942)] Querying state satisfied
APrototypeComponent(2942)] For dependency aProInAProComp, optional: false; to bind: [[MultiplePrototypeRefPair: ref: [{de.foo.bar.bax.checkosgi.AProInAProComp}={component.name=de.foo.bar.bax.checkosgi.AProInAProComp, component.id=2941, service.id=7823, service.bundleid=51, service.scope=prototype}] has service: [true]]]
APrototypeComponent(2942)] Changed state from satisfied to active
APrototypeComponent(2942)] ServiceFactory.ungetService()
APrototypeComponent(2942)] DependencyManager: aProInAProComp close component unbinding from org.apache.felix.scr.impl.manager.ComponentContextImpl@3927bc1d at tracking count 1 refpairs: [[MultiplePrototypeRefPair: ref: [{de.foo.bar.bax.checkosgi.AProInAProComp}={component.name=de.foo.bar.bax.checkosgi.AProInAProComp, component.id=2941, service.id=7823, service.bundleid=51, service.scope=prototype}] has service: [true]]]
APrototypeComponent(2942)] Querying state active
APrototypeComponent(2942)] Changed state from active to satisfied
我不明白为什么我的原型实例无法收集垃圾......
解决方案
新读者更新
从 Apache Felix SCR 2.1.14 开始，这个问题应该得到修复，原始问题中完全有效的代码将不再导致错误行为。
原始答案
首先，感谢您创建一个简单的示例来演示您的问题！
SCR 在停用后应该释放所有组件的引用，这绝对是正确的。对于ReferenceScope.PROTOTYPE_REQUIRED作用域引用，这应该导致服务实例被释放和整理。
可悲的是，似乎 SCR 的这个功能已经有一段时间没有工作了。我代表您提出了https://issues.apache.org/jira/browse/FELIX-5974，因此它应该很快得到修复，但目前“简单”的解决方法是自己控制生命周期。
@Component(
service = GogoShellService.class,
scope = ServiceScope.SINGLETON,
immediate = true,
property =
{
"osgi.command.scope=test",
"osgi.command.function=atest",
}
)
public class GogoShellService {
public String atest() {
Bundle bundle = FrameworkUtil.getBundle(APrototypeComponent.class);
ServiceReference<APrototypeComponent> serviceReference = bundle.getBundleContext().getServiceReference(APrototypeComponent.class);
ServiceObjects<APrototypeComponent> serviceObjects = bundle.getBundleContext().getServiceObjects(serviceReference);
APrototypeComponent service = serviceObjects.getService();
String s = "Hello From: " + service.sayHello();
serviceObjects.ungetService(service);
return s;
}
}
@Component(scope = ServiceScope.PROTOTYPE, service = APrototypeComponent.class, servicefactory = true)
public class APrototypeComponent {
@Reference(scope = ReferenceScope.PROTOTYPE_REQUIRED)
ComponentServiceObjects<AProInAProComp> cso;
AProInAProComp aProInAProComp
@Activate
void start() {
aProInAProComp = cso.getService();
}
@Deactivate
void stop() {
cso.ungetService(aProInAProComp);
aProInAProComp = null;
}
public String sayHello() {
String hello = "Hello From " + this.getClass().getSimpleName() + "(" + this.toString() + ") ";
if (aProInAProComp != null) {
hello += aProInAProComp.sayHello();
}
return hello;
}
}
@Component(scope = ServiceScope.PROTOTYPE, service = AProInAProComp.class)
public class AProInAProComp {
public String sayHello() {
return "Hello From " + this.getClass().getSimpleName() + "(" + this.toString() + ")";
}
}
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