[vlc-devel] VLC Scalability

Rémi Denis-Courmont rdenis at simphalempin.com
Thu Feb 5 11:56:36 CET 2009

On Thu, 5 Feb 2009 11:03:12 +0100, Philip Frey1 <PHF at zurich.ibm.com> wrote:
> we are running an experiment to evaluate the scalability of the VLC in
> mode.
> For some reason we find that the server does not scale beyond 330 clients
> no matter what bitrate our movie is (we are streaming Quicktime content).

Increase the process open files limit.

> When streaming Full HD content (~9Mbps), the number of clients is limited
> by the CPU power of the server. When using Standard Definition content
> and ~3Mbps), the CPU load increases up to about 330 connected client and
> then dropps suddenly to almost 0 and the clients no longer receive any

You typically need 2 sockets per elementary stream (one for RTP and one for
RTCP), plus one socket per client (for RTSP). The default file limit is
1024 on Linux. You do the math...

Admittedly, we could stick to a single pair of RTP/RTCP sockets for all
clients. But that would potentially cause disasters with kernel-level
socket buffering.

Rémi Denis-Courmont

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