Singlethreadmodel in servlet
Also, note that Single Thread Model is pretty resource intensive from the server's perspective.The most serious issue however is when the number of concurrent requests exhaust the servlet instance pool.
In essence, if the servlet implements this interface, the servlet will be thread safe." Note that this is not an ideal solution, since performance may suffer (depending on the size of the instance pool), plus it's more difficult to share data across instances than within a single instance.7.
To share data across successive or concurrent requests, you can use either instance variables or class-static variables, or use Session Tracking.8.
And especially you shouldn't synchronize the service() method! A simple solution to synchronizing is to always synchronize on the servlet instance itself using synchronized (this) .
However, this can lead to performance bottlenecks; you're usually better off synchronizing on the data objects themselves.6.
Ensures that servlets handle only one request at a time. If a servlet implements this interface, you are guaranteed that no two threads will execute concurrently in the servlet's service method.