关于spring xxfactory.getBeanByType

在项目开发过程中，遇到一个jvm 不能回收内存的问题 ，导致到最后old区占100%，服务器一直超时响应很慢，最后自动重启。。。。。

 

通过jstack 查看得到 线程有6-700个线程全部处于阻塞状态：BLOCKED

 

 

"resin-tcp-connection-*:8080-2401" daemon prio=10 tid=0x00002aab3df66000 nid=0x1693 waiting for monitor entry [0x00002aac50f09000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:180)
        - waiting to lock <0x00002aaabe5fd790> (a java.util.concurrent.ConcurrentHashMap)
        at org.springframework.beans.factory.support.AbstractBeanFactory.isTypeMatch(AbstractBeanFactory.java:415)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanNamesForType(DefaultListableBeanFactory.java:223)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:303)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:297)
        at org.springframework.context.support.AbstractApplicationContext.getBeansOfType(AbstractApplicationContext.java:941)
        at org.springframework.beans.factory.BeanFactoryUtils.beansOfTypeIncludingAncestors(BeanFactoryUtils.java:224)
        at org.springframework.beans.factory.BeanFactoryUtils.beanOfTypeIncludingAncestors(BeanFactoryUtils.java:309)

 

 

具体错误见上面，查看了一下spring的源代码

 

 

protected Object getSingleton(String beanName, boolean allowEarlyReference) {
		Object singletonObject = this.singletonObjects.get(beanName);
		if (singletonObject == null) {
			synchronized (this.singletonObjects) {
				singletonObject = this.earlySingletonObjects.get(beanName);
				if (singletonObject == null && allowEarlyReference) {
					ObjectFactory singletonFactory = (ObjectFactory) this.singletonFactories.get(beanName);
					if (singletonFactory != null) {
						singletonObject = singletonFactory.getObject();
						this.earlySingletonObjects.put(beanName, singletonObject);
						this.singletonFactories.remove(beanName);
					}
				}
			}
		}
		return (singletonObject != NULL_OBJECT ? singletonObject : null);
	}

 

 

 

网上这是spring的一个缺陷，但直到最新版本也没有见修复。具体见如URL:

https://jira.springsource.org/browse/SPR-6870

 

 

Spring中  获取一个spring容器管理的Bean可以通过 getBeanByName or getBeanByType 

其中能过前者获取到的beanspring是有加缓存的，而getBeanByType 每次都是重新去生成（其实我也没去深究过他的源码）

 

 

不过我做了一个测试：

 

long startTime = System.currentTimeMillis();
		User user3 = null;
		for(int i=0; i<100000; i++) {
			user3 = BeanFactory.getBean("user");
			user3.print();
		}
		
		long endTime = System.currentTimeMillis();
		
		System.out.println("getBeanByName spend time ：" + (endTime - startTime) + "ms");
		System.out.println("current momory:" + SprintTest.getUsedMemory());
		User user4 = null;
		for(int i=0; i<100000; i++) {
			user4 = BeanFactory.getBean(User.class);
			user4.print();
		}
		
		long end = System.currentTimeMillis();
		System.out.println("getBeanBytype spend time ：" + (end - endTime) + "ms");
		System.out.println("current momory:" + SprintTest.getUsedMemory());

 

 

 

 

Factory方法：

 

	@SuppressWarnings("unchecked")
	public static <T> T getBean(final String name) {
		return (T) ctx.getBean(name);
	}
	
	
	public static <T> T getBean(final Class<T> clazz) {
		return clazz.cast(BeanFactoryUtils.beanOfTypeIncludingAncestors(ctx, clazz));
	}

 

 

 

 

 

结果如下：

 

 

getBeanByName spend time ：86ms

current momory:899560

getBeanBytype spend time ：773ms

current momory:1576440

 

 

 

很震撼。。。。时间直接是数量级的差别，空间也有很大的差别。

建议大家尽量少使用getBeanByType 吧，如果一定需要用的话，可以通过人为的加缓存来解决这种性能问题 ，尽量少使用避免这种BUG出现。

 

 

此外还引出另外一个问题 ，有的同学在Util里面引用一些Sprint管理的类，一般Util的方法都是静态的，他本身不在Sprint容器的管理范围之内，那怎么解决这个方法呢，可以用Sprng工厂去获得bean

 

 

public class BeanFactory implements ApplicationContextAware {
	
	private static ApplicationContext ctx;
	
	private static BeanFactory singleton; 
	
	public BeanFactory() {
	       singleton = this;
	}
	
	public static BeanFactory getInstance(){
		return singleton;
	}
	
	public void setApplicationContext(ApplicationContext ctx)
			throws BeansException {
		BeanFactory.ctx = ctx;
	}
	
	@Autowired
	private User user;
	
	public User getUser() {
		return user;
	}
	
	@SuppressWarnings("unchecked")
	public static <T> T getBean(final String name) {
		return (T) ctx.getBean(name);
	}
	
	
	public static <T> T getBean(final Class<T> clazz) {
		return clazz.cast(BeanFactoryUtils.beanOfTypeIncludingAncestors(ctx, clazz));
	}

 

 

 

 

可以通过BeanFactory.getInstance().getBean("name") 的方法去实现

 

如果是在Spring管理的bean里面调用别的bean的话就简了 或者你通过Spring 的@Autowired注入，或者set 注入 都可以。