I have following problem...I created a Process via ProcessBuilder in this way :
private ProcessBuilder processBuilder;
private Process process;
public void init() {
processBuilder = new ProcessBuilder(
"java", "-jar",
"bam.jar",
host,
);
processBuilder.redirectOutput(ProcessBuilder.Redirect.INHERIT);
processBuilder.redirectError(ProcessBuilder.Redirect.INHERIT);
try {
process = processBuilder.start();
} catch (IOException e) {
e.printStackTrace();
}
}
and I have function who should a kill process :
public void stop() {
process.destroy();
try {
process.waitFor(5, TimeUnit.SECONDS);
} catch (InterruptedException e) {
e.printStackTrace();
}
if (process.isAlive()) {
try {
Thread.sleep(5000L);
} catch (InterruptedException e) {
e.printStackTrace();
}
process.destroyForcibly();
}
}
But killing process sometimes work, but sometimes doesn't work. Any idea?
had similar problem, resolved it by replacing processBuilder.start() with
java.lang.Process process = java.lang.Runtime.getRuntime().exec("command java -jar some.jar");
proccess.destroy();
Since I am stuck for this for a week now and still haven't firgured it out I try to express what I want as cleary as possible.
I have a Server which can handle Multiple Clients and communicates with them.
Whenever a client connects, the server passes the Client's request to my class RequestHandler, in which the clients commands are being processed.
If one of the clients says "SHUTDOWN", the server is supposed to cut them loose and shut down.
It doesn't work.
If only one client connects to the server, the server seems to be stuck in the accept() call and I do not know how to fix this.
THERE is already one response, but please do not take note of it, it was on a different topic which is outdated
I have two approaches and both don't seem to work.
1)If the client writes "SHUTDOWN", the shutdownFlag is set to true (in hope to exit the while loop)
2)If the client writes "SHUTDOWN", the static method shutdown() is called on the Server, which should shut him down
Below you see the implementation of my Server class, the other two classes involved are Client(all he does is connect to the Socket) and RequestHandler (this class processes the Input and writes it) .
I am 98% sure the problem lies within the Server class.
Below this is an even shorter version of the Server with just the methods without any Console outputs which might help understanding it in case you want to copy the code
public class Server {
public static final int PORTNUMBER = 8540;
public static final int MAX_CLIENTS = 3;
public static boolean shutdownFlag = false;
public static ExecutorService executor = null;
public static ServerSocket serverSocket = null;
public static void main(String[] args) {
ExecutorService executor = null;
try (ServerSocket serverSocket = new ServerSocket(PORTNUMBER);) {
executor = Executors.newFixedThreadPool(MAX_CLIENTS);
System.out.println("Waiting for clients");
while (!shutdownFlag) {
System.out.println("shutdown flag ist : " + shutdownFlag);
Socket clientSocket = serverSocket.accept();
Runnable worker = new RequestHandler(clientSocket);
executor.execute(worker);
System.out.println("Hallo");
}
if (shutdownFlag) {
System.out.println("Flag is on");
try {
executor.awaitTermination(10, TimeUnit.SECONDS);
} catch (InterruptedException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
//Stop accepting requests.
serverSocket.close();
} catch (IOException e) {
System.out.println("Error in server shutdown");
e.printStackTrace();
}
serverSocket.close();
}
System.out.println("shutting down");
} catch (IOException e) {
System.out
.println("Exception caught when trying to listen on port "
+ PORTNUMBER + " or listening for a connection");
System.out.println(e.getMessage());
} finally {
if (executor != null) {
executor.shutdown();
}
}
}
public static void shutdown(){
if (shutdownFlag) {
System.out.println("Flag is on");
try {
executor.awaitTermination(10, TimeUnit.SECONDS);
} catch (InterruptedException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
//Stop accepting requests.
serverSocket.close();
} catch (IOException e) {
System.out.println("Error in server shutdown");
e.printStackTrace();
}
try {
serverSocket.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public class Server {
public static final int PORTNUMBER = 8540;
public static final int MAX_CLIENTS = 3;
public static boolean shutdownFlag = false;
public static ExecutorService executor = null;
public static ServerSocket serverSocket = null;
public static void main(String[] args) {
ExecutorService executor = null;
try (ServerSocket serverSocket = new ServerSocket(PORTNUMBER);) {
executor = Executors.newFixedThreadPool(MAX_CLIENTS);
while (!shutdownFlag) {
Socket clientSocket = serverSocket.accept();
Runnable worker = new RequestHandler(clientSocket);
executor.execute(worker);
}
if (shutdownFlag) {
try {
executor.awaitTermination(10, TimeUnit.SECONDS);
} catch (InterruptedException e1) {
e1.printStackTrace();
}
try {
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
serverSocket.close();
}
} catch (IOException e) {
} finally {
if (executor != null) {
executor.shutdown();
}
}
}
public static void shutdown() {
if (shutdownFlag) {
try {
executor.awaitTermination(10, TimeUnit.SECONDS);
} catch (InterruptedException e1) {
e1.printStackTrace();
}
try {
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
If you move the code in main into an instance method on Server (we'll say run here) you can just do new Server().run() inside main. That way you have an instance (this) to work with inside your run method.
Something like this:
class Server {
private boolean shutdownFlag = false; // This can't be static anymore.
public static final Server SERVER = new Server();
public static void main(String[] args) {
SERVER.run();
}
private void run() {
// Here goes everything that used to be inside main...
// Now you have the Server.SERVER instance to use outside the class
// to shut things down or whatever ...
}
}
This pattern isn't actually that great but better would be too long for here. Hopefully this gets you off to a good start.
I have a little problem with my Client-Server Application. When I want to connect more than 1 Client and send smth, or I make logout in my Client and try to connect one more time I got Exception:
"java.io.StreamCorruptedException: invalid type code: 04"
What's the problem? Thank's for help.
Server Code:
class ClientCommunication implements Runnable {
private Socket incoming;
public ClientCommunication(Socket clientSocket) {
incoming = clientSocket;
}
public void run() {
try {
synchronized (this) {
serverObjectOutput = new ObjectOutputStream(
incoming.getOutputStream());
serverObjectInput = new ObjectInputStream(
incoming.getInputStream());
}
} catch (IOException e) {
e.printStackTrace();
}
int operation = -1;
synchronized(this) {
while (true) {
try{
if(serverObjectInput.available() > 0){
operation = serverObjectInput.readInt();
switch(operation) {
case 1:
Employee employee = (Employee) serverObjectInput.readObject();
//CHECK LOGGING DATA
// SEND RESULT = 1 OR RESULT = -1
break;
}
}
} catch(IOException | ClassNotFoundException | SQLException ex)
{
ex.printStackTrace();
}
}
}
}
}
class ServerStart implements Runnable {
private int portNumber;
public ServerStart(int portNumber) {
this.portNumber = portNumber;
}
public void run() {
try {
conn = getConnection();
stat = conn.createStatement();
} catch (SQLException e1) {
e1.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
try {
serverSocket = new ServerSocket(portNumber);
} catch (IOException e) {
e.printStackTrace();
}
try {
while (true) {
Socket incoming = serverSocket.accept();
Runnable r = new ClientCommunication(incoming);
Thread t = new Thread(r);
t.start();
}
} catch (IOException e) {
e.printStackTrace();
}
}
Client Function:
public void actionPerformed(ActionEvent e) {
if (isConnected == false) {
String ServerIP = ip.getText().trim();
int ServerPort = Integer
.parseInt(port.getText().trim());
try {
ClientSocket = new Socket(ServerIP, ServerPort);
clientObjectInput = new ObjectInputStream(
ClientSocket.getInputStream());
clientObjectOutput = new ObjectOutputStream(
ClientSocket.getOutputStream());
isConnected = true;
} catch (IOException ex) {
ex.printStackTrace();
}
synchronized (this) {
try {
ClientLoginFrame login = new ClientLoginFrame();
Employee employee = login.getEmployee();
clientObjectOutput.writeInt(1);
clientObjectOutput.flush();
clientObjectOutput.writeObject(employee);
int result = clientObjectInput.readInt();
if(result == 1)
{
// DO SMTH
}
else {
isConnected = false;
ClientSocket.close();
}
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
}
});
I suspect your problem is that you are sharing the singletons serverInputStream and serverOutputStream between connections. This isn't a problem until you have more than one at which point using the same stream in multiple threads at once corrupts the stream (or makes reading it invalid)
I want to do following operation in ordered wise
1. Stop jetty server
2. Delete used resource from jetty
3. Restart jetty server.
I have done this above using shutdownhook in java as below :
<code>
Thread restartThread = new Thread(){
public void run(){
try {
sleep(5000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String osName = System.getProperty("os.name");
logger.debug("OS name:" + osName);
if (osName != null
&& osName.toUpperCase().startsWith("WINDOWS")) {
Runtime.getRuntime().addShutdownHook(new Thread() {
public void run() {
try {
List<String> cmdLine = new ArrayList<String>();
cmdLine.add("cmd.exe");
cmdLine.add("/C");
cmdLine.add("start");
cmdLine.add("\"\"");
cmdLine.add(getBaseDir() + File.separator + "restart.bat");
final ProcessBuilder pb = new ProcessBuilder(cmdLine);
Process process = pb.start();
if (process.exitValue() == 0) {
// after stopping server delete stores
deleteCertificates();
// restores files
restoreFiles(tmpdir, backupfilelist);
}
//p.waitFor();
} catch (IOException e) {
logger.error("Failed to restart:" + e.getMessage(), e);
}
}
});
System.exit(0);
} else {
try {
Runtime.getRuntime().exec("service appservice restart");
} catch (IOException e) {
logger.error("Failed to restart:" + e.getMessage(), e);
}
}
}
};
restartThread.start();
<code>
my concern is will it do it sequentially execution, otherwise application will fail to restore.
I'm really confused by this: some of my code is not working when i run my program normally in eclipse, but it does wok when i run through each step separately using the debug mode.
Code:
public void showConnectDialog() {
ConnectDialog connectDialog = new ConnectDialog();
connectDialog.setVisible(true);
//Until here, code runs
while(! connectDialog.getConnected()) {};
//The next line does only run in debug
JOptionPane.showMessageDialog(connectDialog, "Connected", "Connected", JOptionPane.INFORMATION_MESSAGE);
}
The connector (is started (as a thread) as soon as the user hits 'connect' in the dialog):
private class ServerConnector implements ActionListener, Runnable {
#Override
public void actionPerformed(ActionEvent e) {
if (! IP_field.getText().equals("")) {
if (! isConnecting) {
new Thread(new ServerConnector(), "ServerConnector").start();
}
}
else {
JOptionPane.showMessageDialog(dialog,
"Enter an IP address",
"Enter IP",
JOptionPane.WARNING_MESSAGE);
}
}
#Override
public void run() {
try {
setConnecting(true);
Socket socket = connect();
if (socket != null) {
ObjectOutputStream oOut = new ObjectOutputStream(socket.getOutputStream());
ObjectInputStream oIn = new ObjectInputStream(socket.getInputStream());
if (login(oOut, oIn)) {
isConnected = true;
setConnecting(false);
}
else {
socket.close();
}
setConnecting(false);
}
}
catch (RSPException e) {
e.printStackTrace();
System.exit(1);
}
catch (Exception e) {
//If an exception occurs, setConnecting() will be true. This
//not good, so it has to be set to false
e.printStackTrace();
setConnecting(false);
}
}
private boolean login(ObjectOutputStream oOut, ObjectInputStream oIn)
throws ClassNotFoundException, IOException, RSPException {
//Send login request action:
oOut.writeObject(new LoginAction(ActionSender.CLIENT, getID(),
getPassword()));
Object obj = oIn.readObject();
if (obj instanceof LoginActionResult) {
LoginActionResult result = (LoginActionResult) obj;
if (result.getResult() == LoginResults.SUCCES) {
return true;
}
else if (result.getResult() == LoginResults.FAIL_ON_ID) {
JOptionPane.showMessageDialog(dialog,
"Invalid password or ID",
"Can't login",
JOptionPane.ERROR_MESSAGE);
return false;
}
else if (result.getResult() == LoginResults.FAIL_ON_PASSWORD) {
JOptionPane.showMessageDialog(dialog,
"Invalid password or ID",
"Can't login",
JOptionPane.ERROR_MESSAGE);
return false;
}
else if (result.getResult() == LoginResults.SERVER_FULL) {
JOptionPane.showMessageDialog(dialog,
"Couldn't connect: \n" +
"Server is full",
"Failed to connect",
JOptionPane.WARNING_MESSAGE);
return false;
}
else {
return false;
}
}
else {
System.out.println(obj);
throw new RSPException("Server is not following the protocol.");
}
}
private void setConnecting(boolean connecting) {
if (connecting) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
connectButton.setEnabled(false);
}
});
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
connectButton.setText("Connecting...");
}
});
}
else {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
connectButton.setText("Connect");
}
});
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
connectButton.setEnabled(true);
}
});
}
isConnecting = connecting;
}
private String getAddressFromTextField() {
return IP_field.getText();
}
private InetAddress getInetAddress(String fullAddress) {
try {
if (fullAddress.contains(":")) {
String[] splitAddress = fullAddress.split(":");
return InetAddress.getByName(splitAddress[0]);
}
else {
return InetAddress.getByName(fullAddress);
}
}
catch (UnknownHostException e) {
return null;
}
}
private int getPort(String fullAddress) {
try {
String[] splittedAddress = fullAddress.split(":");
return Integer.valueOf(splittedAddress[1]);
}
catch (NumberFormatException ex) {
return -1;
}
catch (NullPointerException
| ArrayIndexOutOfBoundsException
| PatternSyntaxException ex) {
//Returning default port value: 25566, because no port was given
return 25566;
}
}
#SuppressWarnings("resource")
private Socket connect() {
Socket socket = null;
InetAddress address = null;
if ((address = getInetAddress(getAddressFromTextField())) == null) {
return null;
}
int port = getPort(getAddressFromTextField());
try {
socket = new Socket(address, port);
}
catch (ConnectException e ) {
Socket retrySocket = null;
if ((retrySocket = retryConnect(address, port)) == null) {
JOptionPane.showMessageDialog(dialog,
"Connection timed out",
"Failed to connect",
JOptionPane.ERROR_MESSAGE);
setConnecting(false);
}
else {
socket = retrySocket;
}
}
catch(IOException e) {
e.printStackTrace();
}
return socket;
}
private Socket retryConnect(InetAddress address, int port) {
Thread waitThread = new Thread(new Runnable() {
#Override
public void run() {
try {
//Will wait 15(000) (milli)seconds before stopping with
//trying to connect.
//One second (1000 millis) is for debugging and testing
Thread.sleep(1000);
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
});
waitThread.start();
while (waitThread.isAlive()) {
try {
return new Socket(address, port);
}
catch (ConnectException e) {
//Do nothing, will re-attempt to connect.
}
catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
private String getID() {
return ID_field.getText();
}
private String getPassword() {
if (getID().equals("master")) {
return "masterPassword";
}
else {
return new String(passwordField.getPassword());
}
}
}
getConnected() returns true as soon as it's connected to the server. The connector is running on a separate thread.
EDIT: I tried to put code in the getConnected() while block, and then it works. Why does it works then and not else?
I had the same Problem, but with some more specification. The code was working fine in 32bit but I had this issue in 64bit (I am using native library so I need to maintain both).
The solution I found is to add Thread.sleep() in the while loop. I don't know why it works, so your guess is as good as mine.
A better solution would probably to implement an Observer Pattern instead of having an infinite loop. But that would require some re-factoring.
Using Thread.sleep(), as the other answers have suggested, should solve the problem but it is not a very good approach. Instead, we should be using Thread.yield().
Why yield and not sleep?
Refer:
Difference between Thread.Sleep(0) and Thread.Yield() and Are Thread.sleep(0) and Thread.yield() statements equivalent?
Why this works?
When we just run the threads, the OS puts them to "idle" state and when it is expected to "wake-up", it does not. On the other hand, in debug mode, we have a controlled environment. The OS has little control over it as everything goes on step-by-step, slowly. If we run the debug a few times without any break-points, after a few successful runs, we should see the same effect.
I had a very similar problem with a "while" loop that wouldn't run and that loop was my main routine. How I got the loop to run was that the very first thing that was done in the loop was a sleep:
try
{Thread.sleep(0);}
catch (Exception e)
{e.printStackTrace();}
This was enough to get everything going.
I had same problem in UIAutomator with UiObject2 wait(Until.findObject(),20) .
Thread.yield() - works for me