Threads are facing deadlock in socket program [migrated]
- by ankur.trapasiya
I am developing one program in which a user can download a number of files. Now first I am sending the list of files to the user. So from the list user selects one file at a time and provides path where to store that file. In turn it also gives the server the path of file where does it exist.
I am following this approach because I want to give stream like experience without file size limitation.
Here is my code..
1) This is server which gets started each time I start my application
public class FileServer extends Thread {
private ServerSocket socket = null;
public FileServer() {
try {
socket = new ServerSocket(Utils.tcp_port);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public void run() {
try {
System.out.println("request received");
new FileThread(socket.accept()).start();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
2) This thread runs for each client separately and sends the requested file to the user 8kb data at a time.
public class FileThread extends Thread {
private Socket socket;
private String filePath;
public String getFilePath() {
return filePath;
}
public void setFilePath(String filePath) {
this.filePath = filePath;
}
public FileThread(Socket socket) {
this.socket = socket;
System.out.println("server thread" + this.socket.isConnected());
//this.filePath = filePath;
}
@Override
public void run() {
// TODO Auto-generated method stub
try
{
ObjectInputStream ois=new ObjectInputStream(socket.getInputStream());
try {
//************NOTE
filePath=(String) ois.readObject();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
File f = new File(this.filePath);
byte[] buf = new byte[8192];
InputStream is = new FileInputStream(f);
BufferedInputStream bis = new BufferedInputStream(is);
ObjectOutputStream oos = new ObjectOutputStream(
socket.getOutputStream());
int c = 0;
while ((c = bis.read(buf, 0, buf.length)) > 0) {
oos.write(buf, 0, c);
oos.flush();
// buf=new byte[8192];
}
oos.close();
//socket.shutdownOutput();
// client.shutdownOutput();
System.out.println("stop");
// client.shutdownOutput();
ois.close();
// Thread.sleep(500);
is.close();
bis.close();
socket.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
NOTE: here filePath represents the path of the file where it exists on the server. The client who is connecting to the server provides this path. I am managing this through sockets and I am successfully receiving this path.
3) FileReceiverThread is responsible for receiving the data from the server and constructing file from this buffer data.
public class FileReceiveThread extends Thread {
private String fileStorePath;
private String sourceFile;
private Socket socket = null;
public FileReceiveThread(String ip, int port, String fileStorePath,
String sourceFile) {
this.fileStorePath = fileStorePath;
this.sourceFile = sourceFile;
try {
socket = new Socket(ip, port);
System.out.println("receive file thread " + socket.isConnected());
} catch (IOException ex) {
ex.printStackTrace();
}
}
@Override
public void run() {
try {
ObjectOutputStream oos = new ObjectOutputStream(
socket.getOutputStream());
oos.writeObject(sourceFile);
oos.flush();
// oos.close();
File f = new File(fileStorePath);
OutputStream os = new FileOutputStream(f);
BufferedOutputStream bos = new BufferedOutputStream(os);
byte[] buf = new byte[8192];
int c = 0;
//************ NOTE
ObjectInputStream ois = new ObjectInputStream(
socket.getInputStream());
while ((c = ois.read(buf, 0, buf.length)) > 0) {
// ois.read(buf);
bos.write(buf, 0, c);
bos.flush();
// buf = new byte[8192];
}
ois.close();
oos.close();
//
os.close();
bos.close();
socket.close();
//Thread.sleep(500);
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
NOTE : Now the problem that I am facing is at the first time when the file is requested the outcome of the program is same as my expectation. I am able to transmit any size of file at first time. Now when the second file is requested (e.g. I have sent file a,b,c,d to the user and user has received file a successfully and now he is requesting file b) the program faces deadlock at this situation. It is waiting for socket's input stream. I put breakpoint and tried to debug it but it is not going in FileThread's run method second time. I could not find out the mistake here. Basically I am making a LAN Messenger which works on LAN. I am using SWT as UI framework.
