More than 2 tcp connections to a server
I am developing a multi-threaded client that connects to a server and downloads the file specified by a URL. After 2 connections are made, each in a different thread, there is no improvement in download speed. I think this is because a limit of 2 connections is being imposed, I think at the OS level.
Can anyone provide a solution to work around this limitation? In .Net one can specify a ConnectionGroupName for a WebRequest, which "tricks" the system into seeing connections from different clients, even though they originate from the same client. Is there an equivalent to this property in Java?
Thanks for reading.
[640 byte] By [
ecruz3a] at [2007-10-2 4:46:52]
> I am developing a multi-threaded client that connects
> to a server and downloads the file specified by a
> URL. After 2 connections are made, each in a
> different thread, there is no improvement in download
> speed. I think this is because a limit of 2
> connections is being imposed, I think at the OS
> level.
It is more likely you are saturating the available bandwidth.
I know I'm not saturating the available bandwidth. I can monitor the network usage in the Windows Task Manager. My Java code tops out at 50%, but using the .NET code mentioned in the original post, I can max out at 100%. The issue is with the number of concurrent connections the client is making.
> I am developing a multi-threaded client that connects
> to a server and downloads the file specified by a
> URL. After 2 connections are made, each in a
> different thread, there is no improvement in download
> speed. I think this is because a limit of 2
> connections is being imposed, I think at the OS
> level.
> I know I'm not saturating the available bandwidth. I
> can monitor the network usage in the Windows Task
> Manager.
You could test your assumption that Windows limits you to 2 connections by running your app on Linux.
> I think this is because a limit of 2
> connections is being imposed, I think at the OS
> level.
Well iIf that was true you would expect to be unable to form the third connection, so obviously that has nothing to do with it. Unless you're trying to convince yourself that the OS will let you form N >> 2 connections but only use two at a time, which doesn't make any kind of sense. A single browser will use more than that on a single Web page.
I would try larger buffers when reading, and I would also try upping the socket receive buffers to around 60k. If you are on Windows this will make a large difference as the default is 8k, which might have been a lot in about 1989, pathetically underpowered now.
EJP
ejpa at 2007-7-16 0:51:40 >
