OSGi DS 原型参考未发布

Question

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带有原型范围的 osgi 声明性服务，我的引用不会被垃圾收集，但如果我这样做使用服务对象。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，它有一个对象的原型引用。如果我使用 osgi 声明性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保留在堆中：

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());
  }
}

所以我尝试以编程方式为我的 HelloPresenter 获取我的服务实例，这工作正常：

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

创建的

serviceObjects.getService();

并与

一起发布

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，这也将生成一个不会被释放和垃圾收集的引用。所以我的经验是，每当你创建一个包含原型引用的服务对象时，在释放服务对象后，引用不会被释放并卡在 jvm 堆中

所以我觉得要么我做错了什么，要么错过了一个参数，这使得我的原型引用永远不会被释放，或者混合 osgi 声明服务和 serviceObjects 有问题......

你知道我如何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 后成为垃圾收集器 ui。

更新

我创建了一个更多示例，其中包含用于执行 gogo shell 命令的单例组件和还包含原型引用的原型对象：

@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) 都会创建一个新的原型实例，之后也应该被销毁，但我仍然可以在我的堆中看到这个对象，并且运行垃圾回收没有不要清理这个...

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被垃圾回收...

Answer 1

新读者更新

从 Apache Felix SCR 2.1.14 开始，这个问题应该得到解决，原始问题中完全有效的代码将不再导致错误行为。

原答案

首先，感谢您创建一个简单的示例来演示您的问题！

您完全正确，SCR 应该在停用后释放您的组件的所有引用。对于 ReferenceScope.PROTOTYPE_REQUIRED 范围内的引用，这应该导致服务实例被释放和整理。

遗憾的是，好像 SCR 的这个功能已经有一段时间没用了。我代表你提出了 https://issues.apache.org/jira/browse/FELIX-5974，所以它应该很快被修复，但现在 "easy" 解决方法是你自己控制生命周期。

@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() + ")";
  }
}

OSGi DS 原型参考未发布

OSGi DS Prototype Reference not released

osgi

declarative-services

liferay-7

vaadin8

新读者更新

原答案