Hi all,

I have a software that simulates web clients and servers to create
network congestion (for the purpose of doing research in network
congestion). In our experiment, a client opens an HTTP connection
to a server, fetches a number of objects, and then closes the
connection. A problem I seem to have right now is that a client
machine cannot simulate more than 3000 connections. When my client
machine simulates more than 3000 connections, it's able to open
a socket but then connect(2) fails with errno 35 (Resource
temporarily unavailable). Another interesting notice is that the
connect(2) system call blocks for a few miliseconds before it
fails although fcntl(2) was used to make the socket non-blocking.
The OS version I am using is FreeBSD 4.3-release.

I used sysctl to bump up kern.maxfiles and kern.maxfilesperproc to
16384. I also bumped up kern.ipc.somaxconn to 8192 on the server
side. I recompiled the kernel with option NMBCLUSTERS=65536 to
increase the number of mbufs. I guess that CPU is not the bottleneck
since I have the same problem regardless whether I use a 300 MHz or
a 1 GHz machine.

Does anyone have any suggestion what kind of resources my client machine
runs out and how I can fix it?

Thanks,
Long

P.S. Please kindly email your reply to me since I am not on the list.


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