Currently, pCampbot turns off the libomv asset cache and has its own texture/mesh cache. This is currently very similar
- there's only one cache for all bots although we mere flag our receipt of the textures/mesh and don't keep the actual
data. Of course, this behaviour can change in the future.
Default agent update in libomv is currently 2 per second by default (Settings.DEFAULT_AGENT_UPDATE_INTEVAL). From
memory, I thought I observed Singularity post about 1 per second but I could be wrong (Diva may know what it really is
now). That was only a couple of observations so may change under different conditions or different viewers.
On 18/11/14 22:35, Dahlia Trimble wrote:
One issue with libomv bots (and I'm not sure if this applies to pCampbot or
not) is that running multiple bots from the
same installation of libomv results in them all sharing the same asset cache so
asset fetches by such clients will be
much lower than normal viewers, perhaps even by an order of magnitude or more.
Another issue is that libomv AgentUpdate runs at a fixed rate of 10/second but
many viewers send at a rate which is
roughly the same as frame draw rate. Bots in general don't really need a high
AgentUpdate rate and 10/second is probably
a good choice. While I agree with Diva that high rates in general are
undesirable due to the extra work they impose on
the region UDP stack, I question how much they can be reduced, or even made
"smart" without degrading user experience
while interacting in a region over a slow or lossy network connection. Some
user applications such as games or
interactive simulations may require fast response to controls and could suffer
if such needs are not considered while
engineering a networking system.
On Tue, Nov 18, 2014 at 1:51 PM, Justin Clark-Casey <[email protected]
<mailto:[email protected]>> wrote:
These are all fixable issues, either with pCampbot improvements or
distributing pCampbot instances amongst more
machines. I expect pCampbot will be built upon to address these points as
required. And this year I successfully
used 4 Amazon c2 large instances for bot running so a more realistic
network load means spinning up more cloud
instances.
I agree that unless you can reproduce an issue you are shooting in the dark
with any changes. And organizing enough
real people to reproduce issues on a regular basis and without a huge
amount of confusing other behaviour is
impossible in practice.
On 14/11/14 16:46, Maxwell, Douglas CIV USARMY ARL (US) wrote:
Classification: UNCLASSIFIED
Caveats: NONE
Dr. Lopez, thank you for sharing your paper. Can you tell me where it
was
peer reviewed and published? I would like to reference it in my
dissertation.
On the topic of bots, the MOSES team has not been able to compose a NPC
agent or bot that accurately replicate the footprint of a human agent
on the
simulator. We believe this is for many reasons:
1) Bots are usually composed on a server on the same network, not
dispersed
across the internet. The bots should be software throttled and noise
introduced into their connections to approximate random access.
2) Bots aren't using full clients, so they are not filling caches and
making the same scene requests as humans in graphical clients.
3) Bots are usually homogenous. They need to be randomly dressed, have
random attachments, and have random inventories.
4) Bots need to move randomly and collide with objects in the scene and
with each other.
5) Bots need to randomly chat with each other and broadcast locally.
We think we can create a NPC solution that satisfies these issues. Will
take some thought and development. Has anyone come close to this?
Goal: Compose bots/NPCs that can approximate the loads of humans
within 90%
certainty. Meaning if we load 100 of these artificial agents into the
MOSES, we are certain that it will accurately behave as if at least 90
humans are logged in.
IMHO, if you can't assign a reliability to a test, then you are just
wasting
your time. This is basic V&V tenants.
v/r -douglas
Douglas Maxwell, MSME
Science and Technology Manager
Virtual World Strategic Applications
U.S. Army Research Lab
Simulation & Training Technology Center (STTC)
(c) (407) 242-0209 <tel:%28407%29%20242-0209>
-----Original Message-----
From: opensim-dev-bounces@__opensimulator.org
<mailto:[email protected]>
[mailto:opensim-dev-bounces@__opensimulator.org
<mailto:[email protected]>] On Behalf Of
Diva Canto
Sent: Friday, November 14, 2014 11:05 AM
To: [email protected] <mailto:[email protected]>
Subject: Re: [Opensim-dev] Modifying the networking stack
On 11/14/2014 6:23 AM, Michael Heilmann wrote:
Thanks for the responses. I'll go into a little more detail:
We have been running several profilers against OpenSimulator on the
MOSES grid, and on my development machine. The tests were to
examine
the loading on the server under several different loads,
specifically
mesh and physics loads. What we found appears to be that no matter
what kind of load we placed on the region, even to the point of
becoming unresponsive due to physics and mesh, that scripting and
physics load were nowhere near the amount of time spent in
OpenSim.Region.ClientStack.__LindenUDP once we had more than one or
two
avatars logged in. We know from previous investigations at our
firewall that network traffic for OpenSim is not that heavy,
especially with low numbers of users.
If this is a problem, and you are running a recent-ish version of core
OpenSim, it sounds like some misconfiguration somewhere. Back in the
summer
of 2013 we had a problem with the server running OSCC'13; the kernel was
configured to run in some sort of special mode that was making
everything
run badly and unpredictably. We fixed the kernel configuration, and
suddenly
things started running much more smoothly-- I don't remember the
details,
but Nebadon may clarify things.
OpenSim these days can handle 50 people on a single simulator without
much
trouble. If you look at figure 7 of my paper
(http://www.ics.uci.edu/~__lopes/documents/summersim14/__gabrielova_lopes_prepri
<http://www.ics.uci.edu/~lopes/documents/summersim14/gabrielova_lopes_prepri>
nt.pdf)
you will see the quantification of "without much trouble." I suggest
that
you reproduce my experimental conditions with pCamBot and check whether
your
numbers are very different from ours. If they are very different, then
there's definitely something odd in your setup, as we were able to
reproduce
these numbers in several machines. Feel free to contact me directly for
details about pCamBot configuration.
Bots aren't real viewers, but they are much better for measuring things
systematically and detecting problems and bottlenecks than relying on
real
users driven by real people. The performance you get with pCamBot will
be
correlated with the performance you get with real users.
I ran several Wireshark captures against a Firestorm viewer logging
into the MOSES public grid ABWIS region, where we hold our office
hours. I saw that with our current configuration, all traffic
between
the server and my client, with the exception of http CAPS and fsapi
calls, were UDP traffic. This is not immediately concerning, as we
have simian serve our mesh and textures directly. The messages are
mostly binary information, so I could not examine closely, but I did
see a lot of messages containing identical ASCII strings, such as
the
name of my avatar.
Hard to say what you saw, but I bet those are the AgentUpdate messages
that
I mentioned before. The viewer sends at least 10/sec. At points, the
viewer
sends much more than 10/sec, up to 60/sec. Again, take a look at my
paper
for understanding what those are, and how OpenSim deals with them since
OSCC'13.
As I said before, it would be nice to understand why the viewer is so
eager
to blabber its status to the server when nothing is going on.
My primary concern is the amount of time spent handling networking,
not necessarily the networking its-self. But there is at least a
portion of messages on the UDP pipeline that are either reliable, or
perhaps should be; and re-implementing a reliable transport over udp
introduces load at the application layer, instead of letting a
low-level reliable transport such as tcp handle it. I went to
university with a guy who implemented a java networking library
completely over UDP, believing that it was faster than a normal TCP
socket; but he was neglecting that the networking hardware handles
the
ACK and retransmission transparently, and without needing for the
messages to be handled manually by the application.
This may just be my opinion, but since I was going to be ecamining
the
network stack anyways, and typically in a client-server scenario the
ability to maintain a persistent reliable connection where the
server
can push important events to the client, that it would be a good
idea. The points about network throttling and QoS are taken, but
wouldn't they also typically affect the UDP stream? Working on
MOSES I
have plenty of problems dealing with external users who operate on
restricted networks, and they cannot see traffic aside from 80 and
443
without dealing with their own IT personnel. The fact that it is
HTTP
over TCP instead of raw TCP makes no difference once it is on a
non-standard HTTP port.
I agree that it would be more prudent to look at improving the
websocket code and the http server, rather than replace it with a
raw
TCP socket, especially given that there are multiple plugins, such
as
jsonsimstats, that use the http functionality directly.
I hope that explains my position a little better. I would love to
hear if there are other plans/ideas in the community to address
time-sinks like this one, networking simply appears to us as a good
starting point to increase performance and scalability of the
system.
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OSVW Consulting
http://justincc.org
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http://justincc.org
http://twitter.com/justincc
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