SpringMVC默认单例的,高并发情况下,如何保

2024-12-02 18:03:32
推荐回答(1个)
回答1:

实质上这种理解是错误的,Java里有个API叫做ThreadLocal,spring单例模式下用它来切换不同线程之间的参数。用ThreadLocal是为了保证线程安全,实际上ThreadLoacal的key就是当前线程的Thread实例。单例模式下,spring把每个线程可能存在线程安全问题的参数值放进了ThreadLocal。这样虽然是一个实例在操作,但是不同线程下的数据互相之间都是隔离的,因为运行时创建和销毁的bean大大减少了,所以大多数场景下这种方式对内存资源的消耗较少,而且并发越高优势越明显。

总的来说就是,单利模式因为大大节省了实例的创建和销毁,有利于提高性能,而ThreadLocal用来保证线程安全性。

另外补充说一句,单例模式是spring推荐的配置,它在高并发下能极大的节省资源,提高服务抗压能力。spring IOC的bean管理器是“绝对的线程安全”。
web项目本身支持多进程
每个请求都是单独的线程,即时同时访问同一个Controller对象,因为并没有修改Controller对象,相当于针对Controller对象而言,只是读操作,没有写操作,不需要做同步处理。

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