CODEWITHSUNDEEP
springmultithreadingcontrollerthread-safetysingleton
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Reputation: 125

Is my app's Controllers thread safe ? Spring 4.1

I am developing an app in spring 4.1 . I know that Controllers / any other bean in spring are not thread safe . ie: Singleton. That mean same instance of Controller will be used to process multiple concurrent requests. Till here I am clear . I want to confirm that do I need to explicitly set @Scope("prototype") or request in the Controller class ? I read on StackOverflow previous post that even if scope is not set as request/prototype , Spring container will be able to process each request individually based on @RequestParams passed or @ModelAttribute associated with method arguements .

So i want to confirm is my below code is safe to handle multiple request concurrently ?

@Controller

public class LogonController  {

/** Logger for this class and subclasses */
protected final Log logger = LogFactory.getLog(getClass());

@Autowired
SimpleProductManager productManager;

@Autowired
LoginValidator validator;

@RequestMapping( "logon")   
public String renderForm(@ModelAttribute("employee") Logon employeeVO)
{   
    return "logon";
}
@RequestMapping(value="Welcome", method = RequestMethod.POST) 
public ModelAndView submitForm(@ModelAttribute("employee") Logon employeeVO,
                        BindingResult result) 
{
      //Check validation errors
    validator.validate(employeeVO, result);

    if (result.hasErrors()) {
        return new ModelAndView("logon");
    }

     if(!productManager.chkUserValidation(employeeVO.getUsername(), employeeVO.getPassword())){
         return new ModelAndView("logon");
            }
    ModelAndView model = new ModelAndView("Welcome");
    return model ;

}
}

Also i have another doubt. since i am using SimpleProductManager productManager; Do i need to specify scope="prototype in its bean declaration in app-servlet.xml ?

Below is my configuration.xml

<bean id="mySessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
    <property name="dataSource"><ref bean="dataSource"/></property>
    <property name="configLocation" value="classpath:hibernate.cfg.xml" />
</bean>

<bean id="productManager" class="com.BlueClouds.service.SimpleProductManager"  >
    <property name="productDao" ref="productDao"/>
</bean> 

<bean id="productDao" class="com.BlueClouds.dao.HbmProductDao"> 
 <property name="sessionFactory"><ref bean="mySessionFactory"/></property>        
</bean>

 <bean id="loginValidator" class="com.BlueClouds.service.LoginValidator"  >
 </bean>

Being singleton single instance of validator is being shared among all request , for that do i need to add scope=request in bean configuration xml or do i need to surround validate() in synchronized block ? Please advise.

Thanks much .

Upvotes: 0

Views: 178

Answers (1)

Duncan
Duncan

Reputation: 717

You can tell your code is thread safe or not by answering following questions

  1. Are there threads might modify a static field, which is not thread safe(ex: arrayList), in the same time?

  2. Are there threads might modify a field of an instance, which is not thread safe, in the same time?

If any answer of the above is yes, then your code is not thread safe.

Since your code doesn't change any field, so it should be thread safe.

The general idea about thread safe is that if there are threads might change/access the same memory section in the same time, then it's not thread safe, which means "synchronized" is needed.

You'd better learn more about stack memory, heap memory and global memory in JAVA. So that you can understand if your code changes the same memory section in the same time or not.

Upvotes: 1

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