Servlet buffering response despite calls to flush()

Question

We have a system where a client makes an HTTP GET request, the system does some processing on the backend, zips the results, and sends it to the client. Since the processing can

Answer 1

I entirely can't reproduce your problem. Below is your code, slightly altered, running in an embedded Jetty server. I ran it in IntelliJ and requested http://localhost:8080 from Firefox. As expected, the "Save or Open" dialog popped up after 1 second. Selecting "save" and waiting for 20 seconds results in a zip file which can be opened and contains 20 separate entries, named foo each containing a single line 100 characters wide and ending with . This is on Windows 7 Premium 64 with JDK 1.6.0_26. Chrome acts the same way. IE, on the other hand, seems to normally wait for 5 seconds (500 bytes), though once it showed the dialog immediately, and another time it seemed to wait for 9 or 10 seconds. Try it in different browsers:

import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHolder;

import javax.servlet.ServletException;
import javax.servlet.http.*;
import java.io.IOException;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

public class ZippingAndStreamingServlet {
    public static void main(String[] args) throws Exception {
        Server server = new Server(8080);
        ServletContextHandler context = new ServletContextHandler(ServletContextHandler.SESSIONS);
        context.setContextPath("/");
        server.setHandler(context);
        context.addServlet(new ServletHolder(new BufferingServlet()), "/*");
        server.start();
        System.out.println("Listening on 8080");
        server.join();
    }

    static class BufferingServlet extends HttpServlet {
        protected void doGet(HttpServletRequest request,
                             HttpServletResponse response) throws ServletException, IOException {
            ZipOutputStream _zos = new ZipOutputStream(response.getOutputStream());
            ZipEntry _ze;
            long startTime = System.currentTimeMillis();
            long _lByteCount = 0;
            int count = 1;
            response.setContentType("application/zip");
            response.setHeader("Content-Disposition", "attachment; filename=my.zip");
            while (_lByteCount < 2000) {
                _ze = new ZipEntry("foo" + count);
                _zos.putNextEntry(_ze);
                byte[] bytes = String.format("%100d", count++).getBytes();
                System.out.println("Sending " + bytes.length + " bytes");
                _zos.write(bytes);
                _lByteCount += bytes.length;
                sleep(1000);
                System.out.println("Zip: " + _lByteCount + " Time: " + ((System.currentTimeMillis() - startTime) / 1000));
                _zos.flush();
            }
            _zos.close();
        }

        private void sleep(int millis) {
            try {
                Thread.sleep(millis);
            } catch (InterruptedException e) {
                throw new IllegalStateException("Unexpected interrupt!", e);
            }
        }
    }
}