Hello!
I would like some help with a piece of java code that i'm having problem.
I have to make simultaneous tcp socket connections every x seconds to multiple machines, in order to get something like a status update packet.
I use a Callable thread class, which creates a future task that connects to each machine, sends a query packet, and receives a reply which is returned to the main thread that creates all the callable objects.
My socket connection class is :
public class ClientConnect implements Callable<String>
{
Connection con = null;
Statement st = null;
ResultSet rs = null;
String hostipp, hostnamee;
ClientConnect(String hostname, String hostip)
{
hostnamee=hostname;
hostipp = hostip;
}
@Override
public String call() throws Exception
{
return GetData();
}
private String GetData()
{
Socket so = new Socket();
SocketAddress sa = null;
PrintWriter out = null;
BufferedReader in = null;
try
{
sa = new InetSocketAddress(InetAddress.getByName(hostipp), 2223);
}
catch (UnknownHostException e1)
{
e1.printStackTrace();
}
try
{
so.connect(sa, 10000);
out = new PrintWriter(so.getOutputStream(), true);
out.println("\1IDC_UPDATE\1");
in = new BufferedReader(new InputStreamReader(so.getInputStream()));
String [] response = in.readLine().split("\1");
out.close();in.close();so.close(); so = null;
try{
Integer.parseInt(response[2]);
}
catch(NumberFormatException e)
{
System.out.println("Number format exception");
return hostnamee + "|-1" ;
}
return hostnamee + "|" + response[2];
}
catch (IOException e)
{
try {
if(out!=null)out.close();
if(in!=null)in.close();
so.close();so = null;
return hostnamee + "|-1" ;
} catch (IOException e1) {
// TODO Auto-generated catch block
return hostnamee + "|-1" ;
}
}
}
}
And this is the way i create a pool of threads in my main class :
private void StartThreadPool()
{
ExecutorService pool = Executors.newFixedThreadPool(30);
List<Future<String>> list = new ArrayList<Future<String>>();
for (Map.Entry<String, String> entry : pc_nameip.entrySet())
{
Callable<String> worker = new ClientConnect(entry.getKey(),entry.getValue());
Future<String> submit = pool.submit(worker);
list.add(submit);
}
for (Future<String> future : list) {
try {
String threadresult;
threadresult = future.get();
//........ PROCESS DATA HERE!..........//
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}
The pc_nameip map contains <hostname, hostip> values and for every entry i create a ClientConnect thread object.
My problem is that when my list of machines contains lets say 10 pcs (which most of them are not alive), i get a lot of timeout exceptions (in alive pcs) even though my timeout limit is set to 10 seconds.
If i force the list to contain a single working pc, i have no problem.
The timeouts are pretty random, no clue what's causing them.
I also faced a complete freeze on the future.get(); line a couple of times.
Am i missing something or could it be an os network restriction problem?
I am testing this code on windows xp sp3.
p.s. all machines are in a local network
Thanks in advance!
