backlog problem?

Joanne Wing Yan Lai joannelai at yahoo.com
Tue Dec 6 07:12:34 UTC 2005


I even tested a similar program of Client Socket in C++ to connect to port
3306, but the exception "Could not bind to port." was caught after 5 or 6
sockets. So I am quite sure it's sth wrong with the OS (RedHat Linux).

--- Joanne Wing Yan Lai <joannelai at yahoo.com> wrote:

> Hi,
> 
> I have implemented a simple java application (J2SE 1.4.2) in which
> contains a server and a client.
> 
> The server side has a ServerSocket to listen to the client messages and
> the client side has a for loop to create many socket to a specific port.
> 
> When I run the client, the following stack trace was printed after 4 or
> 5
> sockets are created successfully.
> 
> java.net.ConnectException: Connection refused
>         at java.net.PlainSocketImpl.socketConnect(Native Method)
>         at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:305)
>         at
> java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:171)
>         at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:158)
>         at java.net.Socket.connect(Socket.java:426)
>         at java.net.Socket.connect(Socket.java:376)
>         at java.net.Socket.<init>(Socket.java:291)
>         at java.net.Socket.<init>(Socket.java:119)
>         at Client.main(Client.java:12)
> 
> I have tested this on both RedHat linux 7.2 and RHEL 3.0 AS and both
> fail.
> However I run on Windows XP, it runs without any error.
> 
> I have increased the ServerSocket backlog parameter on the server side
> to
> a bigger number (default is 50) but it makes no difference. Besides, I
> have modified /usr/include/linux/socket.h in which the constant
> SOMAXCONN
> is changed from 128 to 1024, but it doesn't help as well.
> 
> It seems to be there's some controls or limitations in RedHat Linux
> which
> causes the program to throw exception when the clients connect faster
> than
> the server can accept.
> 
> Any help is appreciated.
> 
> 
> 
> 		
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