java Servlet IllegalStateException: Cannot call sendRedirect() after the response has been committed

Question

Why i don't know but consider the following code,

package net.collanomics.servlet.auth;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class LogoutAccess extends HttpServlet {
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException{
    checkAccess(req,res);
    HttpSession session=req.getSession(false);
    session.removeAttribute("id");
    session.removeAttribute("name");
    session.invalidate();
    res.sendRedirect("/hello-world/login");

}
public void checkAccess(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException{
    HttpSession session=req.getSession(false);
    if(session!=null){
        res.sendRedirect("/hello-world/login");
    }
}
}

I am get exception like this "HTTP Status 500 - Cannot call sendRedirect() after the response has been committed". And complete printStackTrace as follow:-

type Exception report

message Cannot call sendRedirect() after the response has been committed

description The server encountered an internal error that prevented it from fulfilling this request.

exception

java.lang.IllegalStateException: Cannot call sendRedirect() after the response has been committed
org.apache.catalina.connector.ResponseFacade.sendRedirect(ResponseFacade.java:488)
net.collanomics.servlet.auth.LogoutAccess.doGet(LogoutAccess.java:18)
javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
note The full stack trace of the root cause is available in the Apache Tomcat/8.5.9 logs.

I want to know what is the reason behind getting this error and how i can fixed that error.

Thanks...