IO delay causes buffered streams to hang

Question

I'm writing an application that uses the network and in order to test under slow conditions I created custom input/output streams that just puts in a delay in the basic read() and write(int b) methods before calling the method for the stream passed in the constructor. This allows me to find problems where the interface hangs under slow conditions etc. very quickly.
The problem is that on buffered streams (I have specifically had trouble with BufferedReader and BufferedOutputStream) it causes the stream to just hang. It works fine without the stream with the delay but with it something is causing a hang. I think it may have something to do with the network because I don't have the problem with File IO. Does anybody know why a delay would cause a buffered stream to hang?

Answer 1

Well the I know the socket has not timed out. I usually set the delay about 1 to 3 milliseconds. This will happen everytime a read() or write(int b) occurs so it is enough to slow things down.
This is a code sample that shows the basic idea for reading in a file:
import java.io.*;
public class Example
static class SlowInputStream extends InputStream
private InputStream in;
public SlowInputStream(InputStream i)
in=i;
public int read() throws IOException
try { Thread.sleep(3); }
catch(InterruptedException e) {}
return in.read();
public static void main(String[] args)
throws IOException
if(args.length==0)
System.out.println("Need filename.");
System.exit(0);
SlowInputStream sis=new SlowInputStream(
new FileInputStream(args[0]));
BufferedReader in=new BufferedReader(
new InputStreamReader(sis));
String text;
StringBuffer temp=new StringBuffer();
while((text=in.readLine())!=null)
temp.append(text);
temp.append("\n");
System.out.println(temp.toString());
I would have posted a networking example but I create a subclass of PlainSocketImpl to so I can wrap all the streams networking streams and this requires to set the bootclasspath, but the above shows the basic technique.
Thanks