[Icecast] Icecast locks with WARN connection/_accept_connection accept() failed with error 24: Too many open files

Joel Ebel jbebel at ncsu.edu
Wed Jun 1 21:28:33 UTC 2005

I'm running Slackware Linux 10.0, kernel 2.4.26 and icecast 2.2.  We 
usually have less than 100 clients connected, but I have as many as 13 
sources connected at once.  Only 6 are heavily used, and 6 more are just 
fallbacks only used when the primary 6 go down.  There was no suspicious 
behavior I could find in the logs.  All looked just as it normally does. 
  I suspect this happened over time since this instance of icecast has 
probably been running non-stop since early January.


Michael Smith wrote:
> On 6/1/05, Joel Ebel <jbebel at ncsu.edu> wrote:
>>My icecast server has been running happily for months now, but just
>>yesterday it locked up, chewing up all the cpu time it could find, and
>>not allowing connections.  The last snippet of the error log shows this:
> snip...
>>The error had repeated itself for almost 24 hours before I noticed it.
>>Obviously it had too many files open, but I can't account for how.  The
>>logs before the repeating errors look completely normal.  I tried
>>shutting down the streams, which didn't fix it, so I sent it some kills,
>>and it didn't die.  I had to kill -9 it.  Once it restarted it was fine.
>>  Is there some leak preventing icecast from running indefinitely?  Or
>>will I just need to restart it every few months when this happens again?
>>  Has anyone else seen this happen?
> There's at least one, and possibly two bugs here.
> One is that, when the server runs out of file descriptors, from your
> report, it looks like it spins - it should just reject
> connections/fail gracefully. That one should be straightforward to
> fix.
> The second problem is either a) you legitimately ran out of file
> descriptors (the per-process limit should be easy to change, but I
> can't suggest how since you didn't mention your OS), or b) icecast
> leaked file descriptors.
> b) is more likely, unless you had a lot of clients connected (probably
> at least several hundred), and is obviously much worse. You also
> didn't mention what version you're running - if it isn't the latest
> release, please upgrade.
> Was there any strange/suspicious behaviour just before this happened
> visible in the logs? If not, it's likely a slow leak caused in some
> unusual case, which only becomes a problem after some weeks/months
> (but might be exploitable as a DoS attack).
> Mike$

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