ok, I think I know what might be going on, I believe it is hardware
related -- Take a look at the
presentation I did with Lee Fisher at HPC on Wall Street.
Anyway, try the following and lets see if we can alter the behaviour. On
the data centre machines
run qpidd with --workerthreads 4
If that alters the results i'll expand my theory and how to resolve the
hardware side.
Carl.
Andy Li wrote:
Hi Robert and Carl,
Thank you for your response.
The behavior does not seem to depend on the network topology, or the client
machine (as long as it
is distinct from the broker machine). It depends on the broker machine. In
fact, "fast" (1)
brokers show higher performance even over a higher latency link to the
client, than the "slow" (2)
brokers with client sitting on the same switch. Publisher and subscribers
ran together on the same
machine in most tests, but we've tried running them separately today and it
didn't make a
difference.
Details:
--------------
We tested broker on 4 distinct physical machines (A,B,X,Y). Each has a
single 1 Gbit Ethernet
interface. Machines A and B are on the same switch with very low latency
between them. Same for
X,Y. Between (A,B) and (X,Y) there is an intra-city WAN link with capacity
well in excess of 1 Gbit and
latency of .5-1 ms (sync send throughput at about 700-800 msg/sec). For
both types of links, the
capacity is symmetrical. Machines A and B have fast (1) broker behavior; X
and Y - slower (2). Let A->B mean "clients on A, broker on B".
A->X and A->Y exhibit slow, synced pub/sub throughput (2). Even over low
latency link, X->Y and
Y->X exhibit (2). Vice versa, even over high latency link, X->A and X->B
have fast, out-op-sync
pub/sub behavior (1). A->B is a little bit faster than X->B and X->A, but
the difference in
throughput is nowhere near the big disparity between (1) and (2). Also, the
qualitative behavior
(publisher and subscriber throughput out of sync) is the same regardless of
whether the client is
separated by WAN or single switch.
Machine B (one of the "fast" brokers") has OpenSuse 11.1. All other machines
have have CentOS 5.
The "fast" broker machines actually have weaker hardware:
Machines X and Y ("slow" brokers, behavior (2))
Datacenter app servers
CPU: Dual Intel Xeon E5440 2.83 GHz (8 cores); FSB 1333MHz; L2 Cache 12MB
RAM: 8GB
Single 1Gbit NIC
Machines A and B ("fast" brokers, behavior (1))
Dell Optiplex 755 workstations
CPU: Intel Core 2 Quad Q6600 @ 2.4 GHz (4 cores); FSB 1066MHz; L2 Cache 8MB
RAM: 4GB
Single 1Gbit NIC
Thanks,
Andy
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