Tcp round trip time calculation using java

When i do traceroute from one solaris m/c to another using 10 gig network interface it takes 0.073 ms for 40 bytes packets. 开发者_如何学C

When i do the same thing in java, the time is way longer. It is longer even after 10K iteration. What could be the reason ?

Java: Sender (Snippet)

Socket sendingSocket = new Socket(address, RECEIVER_PORT);
 sendingSocket.setTcpNoDelay(true);
 OutputStream outputStream = sendingSocket.getOutputStream();
 byte[] msg = new byte[64]; // assume that it is populated. 
 for (int i = 0; i < 10000; i++) {
    long start = System.nanoTime();
    outputStream.write(msg,0,64);
    outputStream.flush();

    inputStream.read(msg,0,64);  // inputStream is initialized like outputstream 
    long end = System.nanoTime(); 
 }  

It takes way longer 69 millis and it does not even depends upon the byte size. Even if i reduce it to say 1 byte array, it still takes 69 millis. Any comment/Suggestion ?

Other Observation: 1. OutputStream.write and flush only takes 6 micros. 2. Similarly on the other end TCPReceiver side which receives and writes back, it only takes 6 micros.

Solution: Thank you all you responded for this query. I found that it was due to the socket buffer size:

Default buffer size set on solaris m/c.

Received Buffer Size 49152.

Sending Buffer Size 7552.

I increased the socket buffer size and the performance almost matches traceRoute.

You are not comparing like with like. ICMP and TCP are way different protocols.

If you want to decide if the latency is in your code, the JVM, Solaris TCP stack or the network you'll have to start with tcpdump / wireshark etc.

This is probably due to a number of factors. For starters, establishing a TCP channel takes time. There are several packets that have to be sent between both endpoints to establish the reliable medium. That's not the case with ICMP messages, they are simply single packets. In fact, because you are seeing no difference in the time it takes to transmit the data regardless of size, then you can likely assume that the amount of time required to actually transmit the data (you're talking about a very small amount of data in either case on a 10gig connection) is negligible in comparison to the time it takes to establish the channel. Also, it is entirely possible that there is some overhead associated with the fact that you're using Java (a bytecode language) rather than something like C or C++ that runs natively on the hardware.

The time it takes to connect can be about 20 ms. You need to test using an existing connection.

The TCP stack is quite slow going through the kernel. It takes about 50-100 us on many machines. You can reduce this sustantially using kernel bypass drivers/support.