When does servlet release its thread

Question

Assuming no keep alives, when a servlet container is acting as a stand alone server, I assume that the servlet's thread is not released until the entire response is sent to the client (say a web browser). Is this a correct assumption?

But what happens if the servlet is behind a reverse proxy like Nginx? Is the thread released once the response is delivered to Nginx, or is it held until the response is sent to its final client (say a browser)?

Update: Let me try make this a bit more clear.

It takes mere milliseconds (say 2ms) for a response to be sent from servlet to proxy like nginx. But it can then take an additional 80ms (or so) for the final response to be sent from nginx to the browser. Does the servlet release the thread/stream once the response is sent to nginx, or does the servlet hold onto them until the response is sent to the browser (that is the entire 80ms)

Answer 1

Question: I assume that the servlet's thread is not released until the entire response is sent to the client (say a web browser). Is this a correct assumption?

Ans: No it is wrong. Servlet container will just write the content to the socket and return. It is not guaranteed that return from write() method will ensure that the response has reached the client.

Question: Is the thread released once the response is delivered to Nginx, or is it held until the response is sent to its final client (say a browser)?

Ans: When Nginx is behind , then the client for Servlet container is Nginx. It is not aware of actual remote client. So, the thread will be released once the response is written to Nginx.

Answer 2

The server container not being able to send a response to the client will trigger an exception that will be handled by the container. You can enclose the writing to the outputstream or writer by a try catch finally (with close()) but you don't need to, the container will manage, including the return of the thread to the pool. Regards S