[aprssig] So long.... APRS-IS officially has lost 1/2 it's servers.

Dave Anderson KG4YZY dave at aprsfl.net
Sun Mar 2 03:02:49 EST 2008

> design, but it sounds like there's been more trash talk than real
> attempts to resolve the problem through open communication.

It's not trash talk, Scott.    I tried open communication about this in the
past, and the powers to be involved wanted to keep it under wraps.  That's
not my fault.  I would have preferred an open exchange on this.

The current architecture simply cannot grow much more.    In my opinion
we've found a glass ceiling of what Java can do for server code when it
comes to packet per second processing.  The band-aids put in place will only
hold so much longer.

My 8 core box on fourth with 300 connects ran 45% CPU load!!!!    The 4 core
box at third ran 90-95% load.     These are pure simple facts, anyone
wanting to dispute them I can gladly post the MRTG graphs showing just how
much bandwidth and CPU power these boxes ran on for the past year. 

Every packet that flows thru a javaprsrvr has 6 hash tables to flow thru,
and with filtering, that takes processor power.    At the core level, it's
insanely higher as srvr-to-server links mean each server is sent what each
other server is heard, so that quadruples the packet count right there per
second with 4 servers.

The server code also only has one input queue thread that -everything- has
to flow thru on the core servers before it can be processed, and is why the
input queues were backing up on the servers and causing the crashes with the
sudden inrush of CWOP stations - remember these CWOP  stations are almost
all using NTP synchronized time to all poll at the -exact- same second on
the 5's.  

Anyone here reading this - if you don't believe me, watch your process load
on the 5's with javaprsrvr.  You'll see it spike when all the CWOP guys hit,
no matter where you are and if you take a full feed.

Finally I mentioned nothing about Tier2 in this, this is a CWOP issue, not a
Tier2 issue.  I only mention it as it was a mistake for the core to take on
the CWOP stations, that all.

Personally I have always felt that a multi tier system was the best option,
but unfortunately politics prevented the best implementation of that from


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