By Default Servlet is Single or Multi-Thread Model

[bikash]

Hi all Friends,

I want to clear my doubts By Default Servlet is Single-Thread Model or Multi-Thread Model.Can any one please explain it.

Thanks & Regards
Bikash

[Martyn]

By default servelts are intrinsically multithreaded, which means that a single instance can can be accessed by more than one thread.

Go to www.google.com and search on "servlet multithreded".


Cheers

Martyn

[Yashraj Chauhan]

Hi
By default a Servlet is Multithreaded and to make a servlet singlethreaded one has to implement the SingleThreadModel interface.

Regards

Yashraj Chauhan
Java\J2EE Specialist
Wiley Support Team

[khilansingh]

There is no such interface as MultiThreadedModel. Servlets are intrinsically multithreaded. This means a single instance can be accessed by more than one thread.

If the container receives multiple requests for one servlet simultaneously, the service () method of that servlet will be executed concurrently in multiple threads

If a servlet implements the SingleThreadModel interface, the container will not execute the service () method in more than one thread simultaneously.
The servlet container may synchronize access to a single instance of the servlet.
However, servicing requests sequentially seriously hurts performance. To avoid the performance problem, a servlet container may create multiple instances of the servlet class.



Different variables in both models thread safe or not:-
1. Single Thread Model:-
Local variables:- are defined within the body of a method. [Levi] Always thread-safe.

Instance variables:- Instance variables are defined within the class body and are separately assigned to each instantiated object. Thread-safe only for SingleThreadModel

Class or static variables:- Only one copy of a class variable exists across all the instances of the object belonging to the class for which it is declared.
Class variables , or static variables, are shared among all instances of a servlet. NEVER thread-safe
(No, not even if servlet implements SingleThreadModel.)

Request attributes :- Always thread-safe
Session attributes:- NEVER thread-safe
Context attributes :- NEVER thread-safe

Regards
Khilan Singh Raghuwanshi
Java Developer


Thanks & Regards
Khilan Singh

[infantprabu]

i agree with Khilan. it is good answer.

Regards,
Infant Prabu

[murugesanggg]

I also agreed with Khilan Singh .

Can i get some more clarifications regarding to avoid the performance problem, a servlet container may create multiple instances of the servlet class.

For(a servlet container may create multiple instances) that, anything we want do in programmatically?

[dipak2704]

Originally Posted by khilansingh

There is no such interface as MultiThreadedModel. Servlets are intrinsically multithreaded. This means a single instance can be accessed by more than one thread.

If the container receives multiple requests for one servlet simultaneously, the service () method of that servlet will be executed concurrently in multiple threads

If a servlet implements the SingleThreadModel interface, the container will not execute the service () method in more than one thread simultaneously.
The servlet container may synchronize access to a single instance of the servlet.
However, servicing requests sequentially seriously hurts performance. To avoid the performance problem, a servlet container may create multiple instances of the servlet class.



Different variables in both models thread safe or not:-
1. Single Thread Model:-
Local variables:- are defined within the body of a method. [Levi] Always thread-safe.

Instance variables:- Instance variables are defined within the class body and are separately assigned to each instantiated object. Thread-safe only for SingleThreadModel

Class or static variables:- Only one copy of a class variable exists across all the instances of the object belonging to the class for which it is declared.
Class variables , or static variables, are shared among all instances of a servlet. NEVER thread-safe
(No, not even if servlet implements SingleThreadModel.)

Request attributes :- Always thread-safe
Session attributes:- NEVER thread-safe
Context attributes :- NEVER thread-safe

Regards
Khilan Singh Raghuwanshi
Java Developer


Thanks & Regards
Khilan Singh

Hi Thilan

Its really good way to put info about thread safe variables/attributes.

Best Regards

Dipak S