Internal error while committing HTTP response

Question

I got this error when I made the stress test to our system (5 users). The error does not Occur when using only 1 user and occurs rarely if concurrent users is set to 20. But with 5 users i got about 200 errors in 10 minutes (Total calls was about 1600).
Internal error while committing HTTP response
java.lang.RuntimeException: Internal Server Error, out was null
     at com.evermind.server.http.EvermindHttpServletResponse.commit(EvermindHttpServletResponse.java:271)
     at com.evermind.server.http.EvermindServletOutputStream.flushBuffer(EvermindServletOutputStream.java:80)
     at com.evermind.server.http.EvermindServletOutputStream.flushBuffer(EvermindServletOutputStream.java:56)
     at com.evermind.server.http.EvermindServletOutputStream.flush(EvermindServletOutputStream.java:269)
     at javax.imageio.stream.FileCacheImageOutputStream.flushBefore(FileCacheImageOutputStream.java:212)
     at com.sun.imageio.plugins.png.ChunkStream.finish(PNGImageWriter.java:120)
     at com.sun.imageio.plugins.png.PNGImageWriter.write_IHDR(PNGImageWriter.java:368)
     at com.sun.imageio.plugins.png.PNGImageWriter.write(PNGImageWriter.java:1071)
     at javax.imageio.ImageWriter.write(ImageWriter.java:591)
     at javax.imageio.ImageIO.write(ImageIO.java:1434)
     at javax.imageio.ImageIO.write(ImageIO.java:1508)
     at com.genimap.map.PngFormat.getStream(PngFormat.java:40)
     at com.genimap.test.BPC_Tester.doGet(BPC_Tester.java:81)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
     at com.evermind.server.http.ServletRequestDispatcher.invoke(ServletRequestDispatcher.java:765)
     at com.evermind.server.http.ServletRequestDispatcher.forwardInternal(ServletRequestDispatcher.java:317)
     at com.evermind.server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:790)
     at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:270)
     at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:112)
     at com.evermind.util.ReleasableResourcePooledExecutor$MyWorker.run(ReleasableResourcePooledExecutor.java:192)
     at java.lang.Thread.run(Thread.java:534)
The code looks like this: (bi is BufferedImage 300*300 pixels)
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
MapParams mp=getMapParams(request);
BufferedImage bi=gm.getMap(mp,null);
PngFormat.getStream(bi,response.getOutputStream());
The class PngFormat contains only one method:
public static void getStream(BufferedImage imageData, OutputStream out) throws IOException
          ImageIO.write(imageData,"png",out);
And i have not touched the response object before call PngFormat.getStream(bi,response.getOutputStream());
The users get "Could not get data!". What should i do? This works fine with Bea WebLogic.
Regards
Rami

Answer 1

Just forget to add. The OC4J where I run this is:
C:\OC4J\j2ee\home>java -Xms256m -Xmx512m -jar oc4j.jar
04/02/18 15:33:06 Oracle Application Server Containers for J2EE 10g (9.0.4.0.1)