Icecast - Aug 2004 - weird differences between stats (xml vs. admin interface)

While maintaining the Relay-Server for Radio Subether [1] the official Chaos
Communication Camp [2] Radio Station I noticed some weird behaviour.

We don’t have QoS for the Relay-Path, so the Relay started pretty soon to be 
unstable. Especially the higher bandwidth streams are very often unavailable. To
monitor this behaviour I was constantly reloading the "List
MountPoints" page AND the normal status.xsl/stats.xml [3] page. Soon I
noticed a big discrepancy between both readouts. The admin-readout was way
higher than the status.xsl-readout.

This was reproducible under following circumstances:
1. stable relay
2. increasing number of listeners (~70 on both readouts)
3. relay gets unstable
4. status.xsl shows that all mountpoints are unavailable / random mountpoints
get into available status (1-3 listeners) on repeated page-reloads &
admin-interface shows all/most mountpoints as available with much higher
listener count.

While checking the availability of each stream with Winamp I developed an
theory:
When listening to a stream on the relay it starts to rebuffer pretty often or
even takes really long to rebuffer. So maybe the code generating the stats.xml
file dumps all listeners of the stats on an "disconnected from source
event" although they seem to stay connected. This is also what is shown by
the listclients.xsl in the admin interface - many listeners have high
"connected for" counts although the stats.xml had shown this
mountpoint several times as unavailable.

Has anyone else noticed such behaviour? Is it a bug or a feature? ;)

Thomas

[1] Radio Subether: http://www.subether.de
[2] Chaos Communication Camp: http://www.ccc.de/camp/
[3] status page: http://alft.afthd.tu-darmstadt.de:8000/status.xsl
    will be available until 10.08.03

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