Cause of Servlet's 'Response Already Committed'

Question

What are the common possibilities to encounter this exception in servlet - Response Already committed?

Solution

The response gets committed because of the following reasons:

• Because the Response buffer has reached the max buffer size. It could be because of the following reasons:

    > the bufferSize in JSP page has reached.You can increase the JSP buffer size 
      in page directive. See here, 
  
     <%@ page buffer="5kb" autoFlush="false" %>
  
    > the server default response max buffer size has reached.You can increase    
      the server default max buffer size.
  
      ServletRespnse.setBufferSize()
  

• Some part of the code has called flushed on the response , i,e, invoked the method HttpServletResponse.flushBuffer().

• Some part of the code has flushed the OutputStream or Writer, i,e, invoked the method HttpServletResponse.getOutputStream().flush() or `HttpServletResponse.getWriter().flush()

• If you have forwarded to another page, where the response is both committed and closed. For example, when response.sendRedirect() has been called, the response is committed.

Comments

[Sriram]

Thanks for the reply. Deliberately we never call any of these. But, flush="true" would cause this? So, what are the measures to consider to avoid this?

[Ramesh PVK]

Increase the buffer size of the jsp.

[Sriram]

How to do this? Can you explain with some example?

[Ramesh PVK]

You are having JSP or servlet?

[Sriram]

I actually would like to know the exact cause of this. This occurs both in servlet / jsp. You primarily focused on buffer size. Are there any other points to consider to avoid this. Anyways, your reply certainly helps me. Thanks.

[Ramesh PVK]

This can happen in several cases. Have listed all the cases. Added one more case as well.

[Sriram]

What you mean by this the response is both committed and closed ?

[Ramesh PVK]

Committed means just writing headers. Close means writing headers + writing response + close stream. Such that you cannot write any more content.

[smwikipedia]

Check this thread (stackoverflow.com/questions/34292303/…). You can still write to client even after you call HttpServletResponse.flushBuffer().

[Ramesh PVK]

Yes, Sending data is different from committing !! Committing data is just writing headers. In my discussion above committing data means writing headers.