java - Write to socket directly and get TCP ZeroWindow -

just can see, send request specific socket every 10 seconds directly( remain alive , detected ), can send twice. using wireshark, found third package send has tcp zerowindow , cannot send server. following packages. usually, window size should remain @ normal level instead of decreasing time. what's wrong source code? appreciated!

three packages got:

source code: simple

public class pediy {      public static void main(string[] args) throws ioexception {          url url = new url("http://bbs.pediy.com");         socket socket = null;         printwriter os = null;         bufferedreader = null;          while(true) {              socket = new socket(url.gethost(), 80);             os = new printwriter(socket.getoutputstream());              string request = "get / http/1.1\nhost: bbs.pediy.com\nproxy-connection: keep-alive\naccept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\nuser-agent: mozilla/5.0 (windows nt 6.1) applewebkit/537.17 (khtml, gecko) chrome/24.0.1312.56 safari/537.17 coolnovo/2.0.6.12\naccept-encoding: gzip,deflate,sdch\naccept-language: en-us;q=0.6,en;q=0.4\naccept-charset: utf-8;q=0.7,*;q=0.3\n";             try {                 while (true) {                      os.println(request);                     os.flush();                      system.out.println("finished");                     thread.sleep(1000*10);                 }              } catch (exception e) {                 system.out.println("error" + e);             } {                 closeall(socket, os);             }         }     }      private static void closeall(socket socket, printwriter os) throws ioexception {         if(socket != null) socket.close();         if(os != null) os.close();     } } 

this means other side of tcp connection not consuming (reading) data send, tcp flow control kicks in slow sender down.