Random Transfer Behavior / Problem
Status: Alpha
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Hi,
I am using a UDT-Java server and client to transmit large files; at present I am just trying to get it to work on localhost. I have run into an issue where file transfers are randomly interrupted mid-transfer, always at different locations. To start out I am just transferring a 5 MB PDF test file. Transmission ends randomly anywhere after 19 KB to about 3 MB.
If I place breakpoints at the beginning of the code and step through it (using Netbeans) the transfer usually completes without any problem. Just running the compiled jar causes interrupted transmissions. This happens both in Linux and Windows environments.
The basic client/test code looks like this:
int port = 10057;
UDT_Server the_server = new UDT_Server(port);
Thread x = UDTThreadFactory.get().newThread(the_server);
x.start();
UDTClient the_client = UDTClient(InetAddress.getLocalHost(), (port+1));
the_client.connect("127.0.0.1", port);
File file = new File("received.pdf");
FileOutputStream fout = new FileOutputStream(file);
UDTInputStream in = the_client.getInputStream();
InputStream in_ = in;
byte xx = new byte; int yy = 0;
while ((yy = in_.read(xx)) > 0) {
fout.write(xx, 0, yy);
}
fout.close();
the_client.shutdown();
And the relevant server code is:
UDTSocket clientSocket = null;
clientSocket = this.socket.accept();
OutputStream out = clientSocket.getOutputStream();
File file=new File("Newcomers_brochure.pdf");
FileInputStream fis = FileInputStream(file);
long size=file.length();
Util.copy(fis, out, size, true);
fis.close();
clientSocket.close();
As far as I can tell, what seems to happen is that the receiver thread closes down before before the entire file is transferred, leaving in the end one sender thread hanging indefinitely. In the sender thread it basically hangs at the flush() method in Util.copy(.
This is a typical execution log generated by an interrupted transmission:
run:
Creating Server on Port: 10057
07-Jul-2011 10:54:33 udt.UDTServerSocket <init>
INFO: Created server endpoint on port 10057
UDT Server Socket Created. 0.0.0.0
Server thread started!
07-Jul-2011 10:54:33 udt.UDPEndPoint start
INFO: UDTEndpoint started.
07-Jul-2011 10:54:33 udt.UDTClient <init>
INFO: Created client endpoint on port 10058
07-Jul-2011 10:54:33 udt.UDTSession <init>
INFO: Using udt.UDTCongestionControl
07-Jul-2011 10:54:33 udt.ClientSession <init>
INFO: Created udt.ClientSession@1749757
07-Jul-2011 10:54:33 udt.UDPEndPoint addSession
INFO: Storing session <96>
07-Jul-2011 10:54:33 udt.UDPEndPoint start
INFO: UDTEndpoint started.
07-Jul-2011 10:54:33 udt.ClientSession sendHandShake
INFO: Sending ConnectionHandshake , mySocketID=96, initialSeqNo=1052671622, packetSize=1400, maxFlowWndSize=10240, socketType=1, destSocketID=0]
07-Jul-2011 10:54:33 udt.UDTSession <init>
INFO: Using udt.UDTCongestionControl
07-Jul-2011 10:54:33 udt.ServerSession <init>
INFO: Created udt.ServerSession@1960f05 talking to /127.0.0.1:10058
07-Jul-2011 10:54:33 udt.UDPEndPoint addSession
INFO: Storing session <97>
07-Jul-2011 10:54:33 udt.ServerSession received
INFO: Received ConnectionHandshake
07-Jul-2011 10:54:33 udt.UDTSession setState
INFO: udt.ServerSession@1960f05 connection state CHANGED to <1>
07-Jul-2011 10:54:33 udt.ServerSession handleHandShake
INFO: Sending reply ConnectionHandshake , mySocketID=97, initialSeqNo=1052671622, packetSize=1400, maxFlowWndSize=10240, socketType=1, destSocketID=96]
07-Jul-2011 10:54:33 udt.UDTSession setState
INFO: udt.ServerSession@1960f05 connection state CHANGED to <2>
07-Jul-2011 10:54:33 udt.ClientSession received
INFO: Received connection handshake from Destination
ConnectionHandshake
07-Jul-2011 10:54:33 udt.UDTSession setState
INFO: udt.ClientSession@1749757 connection state CHANGED to <2>
UDT Socket Accepted!
07-Jul-2011 10:54:33 udt.UDTSender start
INFO: Starting sender for udt.ServerSession@1960f05
07-Jul-2011 10:54:34 udt.ClientSession connect
INFO: Connected, 1 handshake packets sent
07-Jul-2011 10:54:34 udt.UDTClient connect
INFO: The UDTClient is connected
Client connected! - udt.UDTClient@1b1aa65
07-Jul-2011 10:54:34 udt.UDTSession setState
INFO: udt.ServerSession@1960f05 connection state CHANGED to <4>
07-Jul-2011 10:54:34 udt.ServerSession received
INFO: Connection shutdown initiated by the other side.
07-Jul-2011 10:54:34 udt.UDPEndPoint doReceive
INFO: SocketException: socket closed
07-Jul-2011 10:54:34 udt.UDTReceiver$1 run
INFO: STOPPING RECEIVER for udt.ServerSession@1960f05
07-Jul-2011 10:54:34 udt.UDTSender$1 run
INFO: STOPPING SENDER for udt.ServerSession@1960f05
07-Jul-2011 10:54:34 udt.UDTReceiver$1 run
INFO: STOPPING RECEIVER for udt.ClientSession@1749757
BUILD STOPPED (total time: 5 seconds)
Any help is greatly Appreciated!
Alex
OK - in retrospect, this was obvious: the receiving buffer is depleted faster than it is filled, so it reaches a length of 0 ocasionally, which causes this code to exit prematurely:
while ((yy = in_.read(xx)) > 0) {
fout.write(xx, 0, yy);
}
Solution: check for ">-1" in the loop; what I actually implemented is to send the size of the data to be expected first, and then read from the input stream until that number is reached.