Question: How Do I Make My Spring Controller Thread Safe?

What is spring bean life cycle?

A “Spring bean” is just a Spring managed instantiation of a Java class.

The Spring IoC container is responsible for instantiating, initializing, and wiring beans.

The container also manages the life cycle of beans.

Spring provides several ways through which you can tap into the bean lifecycle..

Is spring service a singleton?

Yes, they should be of scope singleton . Services should be stateless, and hence they don’t need more than one instance. … singleton is the default scope in spring, so just leave your bean definitions as they are, without explicitly specifying the scope attribute. You can read more about scopes in the spring docs.

Is spring rest controller thread safe?

In Spring’s approach to building RESTful web services, HTTP requests are handled by a controller. … Controller is, thread-safe class, capable of handling multiple HTTP requests throughout the lifecycle of an application.

Is HashMap thread safe?

HashMap is non synchronized. It is not-thread safe and can’t be shared between many threads without proper synchronization code whereas Hashtable is synchronized. … HashMap allows one null key and multiple null values whereas Hashtable doesn’t allow any null key or value.

Is @service thread safe?

No, for the default the scope of the @Service is Singleton. So it`s not thread-safe. If a bean is Singleton, there is one instance for all the application. So when 5 thread pass there, the value will change after each call.

How spring Singleton works in multi threading applications?

2.In Spring every request is executed in separate thread. For example,when 2 users want to login at the same time, JVM creates 2 threads: one thread for first user, another one for second user. And these threads work with singleton bean separately. … That is why, every thread can access objects in heap.

What is the difference between Singleton and prototype scope in spring?

Singleton: Only one instance will be created for a single bean definition per Spring IoC container and the same object will be shared for each request made for that bean. Prototype: A new instance will be created for a single bean definition every time a request is made for that bean.

How do you make a class thread safe?

The best way to achieve thread safety is to avoid shared state. For the state, you need to share you can either use message parsing together with immutable classes or the concurrent data structures together with synchronized blocks and volatile fields.

Is StringBuffer thread safe?

StringBuffer is thread-safe meaning that they have synchronized methods to control access so that only one thread can access StringBuffer object’s synchronized code at a time.

How do I make an ArrayList thread safe?

A thread-safe variant of ArrayList in which all mutative operations (e.g. add, set, remove..) are implemented by creating a separate copy of underlying array. It achieves thread-safety by creating a separate copy of List which is a is different way than vector or other collections use to provide thread-safety.

Is servlet thread safe?

By default, servlets are not thread-safe. … To make a servlet or a block within a servlet thread-safe, do one of the following: Synchronize write access to all instance variables, as in public synchronized void method() (whole method) or synchronized(this) {…} (block only).

Is @component a singleton?

2 Answers. Yes, that is correct, @Component is a Spring bean and a Singleton. About singletons – spring beans are all in singleton scope by default. The only thing you have to have in mind is that you should not store state in field variables (they should only hold dependencies).

What is difference between Java Singleton and Spring Singleton?

In summation, Spring guarantees exactly one shared bean instance for the given id per IoC container, unlike Java Singletons, where the Singleton hardcodes the scope of an object such that one and only one instance of a particular class will ever be created per ClassLoader.

How can we make singleton class thread safe in spring?

Spring will create a Singleton , but if its mutable then it might not be thread safe. IT’S programmer responsibility to take care the spring bean class such way it should be thread safe. In Spring, singleton beans will not have any state (stateless). Singleton bean scope ensures that single instance per BeanFactory.

Is Singleton bean thread safe in spring?

Spring singleton beans are NOT thread-safe just because Spring instantiates them. Sorry. Spring just manage the life cycle of singleton bean and maintains single instance of object. Thread safety has nothing to do with it.

Does spring create a new thread for each request?

In Spring, every request is executed in a separate thread. For example, when two users want to log in at the same time, the JVM creates two threads: one thread for the first user and another one for the second user.

How do I make a HashMap thread safe?

ConcurrentHashMap. get() is thread safe. You can make HashMap thread safe by wrapping it with Collections. synchronizedMap() .

Is ArrayList thread safe?

Any method that touches the Vector ‘s contents is thread safe. ArrayList , on the other hand, is unsynchronized, making them, therefore, not thread safe. With that difference in mind, using synchronization will incur a performance hit. So if you don’t need a thread-safe collection, use the ArrayList .

Why Singleton is not thread safe?

Thread Safe Singleton: A thread safe singleton in created so that singleton property is maintained even in multithreaded environment. To make a singleton class thread-safe, getInstance() method is made synchronized so that multiple threads can’t access it simultaneously. Pros: … It is also thread safe.

How do I make a spring bean thread safe?

If you want to make sure your bean is thread-safe, you should go for the @RequestScope. As the name suggests, Spring binds such bean to a particular web request. Request beans aren’t shared between multiple threads, hence you don’t have to care about concurrency. But hang on a minute.

Why Spring controller is Singleton?

By default, Spring beans are singletons. Spring suggests to use singletons for stateless beans like controllers and DAOs, and prototype scope for stateful beans. The Struts2 Actions are not singletons because they carry state. … The controller itself doesn’t hold state, so a singleton makes sense.