Read/write mysteriously high flow in a pipeline, why?

Hello people,

I'm quite new to java programming. I'm trying to implement a pipeline procedure:
client connects to server socket and starts to send a file to the server on the basic package. In my case, I use the package of 64KB for sending file of 1 GB. After each packet to the client, the server stores the package to disk. Move Server to receive the next packet.

Server:

ServerSocket ss = (socketWriteTimeout > 0)?
ServerSocketChannel.open () t:System.NET.Sockets.Socket (): new ServerSocket();
Server.bind (ss, socAddr, 0);
ss.setReceiveBufferSize(128*1024);
Taking s = ss.accept ();
s.setTcpNoDelay (true);

In DataInputStream = new DataInputStream (new buffer (NetUtils.getInputStream (s), 512));

Then, for each packet of 64 k, I get and write to disk (specifically buffer for the core, unsynchronized)

long (EDT) 1 = System.currentTimeMillis ();

While (toRead > 0) {}
toRead-= in.read (buf.array (), buf.limit (), toRead);
}

long time2 = System.currentTimeMillis ();

File f = new File (fileName);
FileOutputStream out = new FileOutputStream (new RandomAccessFile(f,_"rw").getFD ())

long Time3 = System.currentTimeMillis ();

out. Write (buf, 0, BUFFER_SIZE);
out. Flush();

long years4 = System.currentTimeMillis ();
....

Client:

Socket s = new Socket (srv, port);
s.setSendBufferSize(128*1024);

DataOutputStream sockOut = new DataOutputStream)
new BufferedOutputStream (NetUtils.getOutputStream (s, writeTimeout),
512));

long worm = 0;
While (ver < 1024 * 1024 * 1024)
{

Then get a 64 k buf
sockOut.write (buf.array (), buf.position (), buf.remaining ());
Worm = buf.remaining ();
}
...

I have record receive time and disc for each packet writing time and accumulate on them at the end.
My machine is using 1 Gbps ethernet card, which gives me 102 MB/s speed n/w testable. My written disc rate is about 70 MB/s. I use Linux 2.6.31.
The interesting thing is that, for a 1 GB file that accumulation of setting time is only 4.6 seconds.

My guess is because I put the SO_RCVBUF, SO_SNDBUF, sockOut.write () of the client immediately returns when he wrote the package of 64 KB in the send buffer, then that server side, in.read () back at once when he read 64 KB of the receive buffer. So the actual transfer is made by someone else, not the write() or read() function. This guy sends data from client to server whenever the beef on each side is available.

My guess is just? Please advice.

Elton

But that triggers the transfer of actual data?

The kernel does when the data arrives in the receive buffer.

The socket transfer is initiated by the post () write(), each recorder gave in their SO_SNDBUF or SO_RCVBUF and the other have free space.

The transfer of socket is triggered on write whenever there is sending data in buffer management and the other end has to free space in its socket receive buffer. It is triggered receive every time he's given in the socket receive buffer.

And do you have any idea where can I find the details of the implementation like this?

Stevens, TCP/IP Illustrated volumes I, II and III.

I joined just extracted from code, not full version

More reason to shoot him.

I don't have your advice to not use BufferedOutputStream on socket. Why not?

Because you don't want no latency, as I said. But I would use on the file, so that you write-aligned block drive pieces of say 8192 bytes.

Tags: Java

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