[Icecast-dev] icecast relay server performance testing

Popov, Zahar zahar.popov1978 at yandex.com
Fri Jun 10 11:00:15 UTC 2016

Hi Philipp
Thank you for chiming in.

The only reason i use the -kh fork is because it seemed to be more recent. I had this performance issue with the regular version and tried the fork.

I realize that the problem can be with the TCP stack parameters. I had no problem getting about 800Mbps between these machines when using iperf. Certainly, the workload completely different, but at least i know that the TCP stack is somewhat operational.

Do you happen to know specifically what’s broken?

I don’t have access to a physical data center this is why i would like to use either EC2 or Azure.


> On Jun 10, 2016, at 7:09 PM, Philipp Schafft <lion at lion.leolix.org> wrote:
> Good noon,
> On Fri, 2016-06-10 at 12:50 +0900, Zahar Popov wrote:
>> Hello
>> I'm trying to measure the performance of the icecast relay server on
>> 64kbps streams.
>> The server is running in AWS [...]. I'm using the icecast-kh fork.
>> [...]
>> I'm able to go up to around 9K simultaneous connections to the server
>> (from two machines). [...]
> First: -kh is a independent fork. So I can hardly speak for it. This
> answer is completely based on the (often wrong) assumption that in this
> case behaves exactly like the official Icecast2 in any stable and
> supported version.
>> It doesn't matter if i run one or more instances of the relay server,
>> the limit seems to be OS global so when one instance is running with
>> 5K connections and the other instance is getting close to 4K
>> connections they both start dropping connections.
>> I assume that there is some other setting of the stack that i didn't
>> configure so i was wondering if anybody was able to run a few dozens
>> of thousands of connections on one server. 
> This should give you the hint: It's not a problem of Icecast2 as it
> doesn't depend on the processes.
> Basically: AWS is well known for their broken TCP stack. There is no
> reason to run Icecast2 on AWS. Just use a normal server and be fine.
> What you see above is just AWS's maximum connection limit per instance
> or something. (But there are more problems known with AWS's TCP stack
> that affect real world deployments of Icecast2.)
> Have a nice day!
> -- 
> Philipp.
> (Rah of PH2)

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