Blocking socket is not blocking.

Question

Hello
I'm using the java.net.Socket class in JDK1.4 and hope that the read() on InputStream will block until there is data.
However, the call to read() is not blocking but return me the end-of-stream symbol (-1). Because I want it to block (no timeout set) to save CPU time, how I do. Following, please find a code-example:
public class Server implements Runnable {
private java.net.Socket clientSock;
public Server(java.net.Socket Sock) {
clientSock = Sock;
new Thread(this).start();
public void run() {
try { while (true) { clientSock.getInputStream.read(); }
} catch (Exception Ex) { /* Never occur */ }
public static final void main(String args[]) {
try {
java.net.ServerSocket servSock = new java.net.ServerSocket(54321);
while (true) { new Server(servSock.accept()); }
} catch (Exception Ex) { /* Never occur */ }
This example takes 100% CPU load on my machine as soon as there is one connection. Why? Broken JDK?

Answer 1

Try putting a sleep call in your loop...otherwise this single thread will take up all you CPU and will not yeild to the other threads. Set you SLEEP_TIME based on how long you want the thread to sleep before polling for data on the socket...
try {
while (true) {
clientSock.getInputStream.read();
Thread.sleep(SLEEP_TIME);
} catch (Exception Ex) { /* Never occur */ }
Hello
I'm using the java.net.Socket class in JDK1.4 and hope
that the read() on InputStream will block until there
is data.
However, the call to read() is not blocking but return
me the end-of-stream symbol (-1). Because I want it to
block (no timeout set) to save CPU time, how I do.
Following, please find a code-example:
public class Server implements Runnable {
private java.net.Socket clientSock;
public Server(java.net.Socket Sock) {
clientSock = Sock;
new Thread(this).start();
public void run() {
try { while (true) {
) { clientSock.getInputStream.read(); }
} catch (Exception Ex) { /* Never occur */ }
public static final void main(String args[]) {
try {
java.net.ServerSocket servSock = new
= new java.net.ServerSocket(54321);
while (true) { new Server(servSock.accept()); }
} catch (Exception Ex) { /* Never occur */ }
This example takes 100% CPU load on my machine as soon
as there is one connection. Why? Broken JDK?