skaller wrote:
> 
> BTW: there is a 'performance' target in the build system 
> which builds a custom driver and spawns threads and sends 
> them messages.
> 
> This test make 500,000 threads and sends each one a message.
> On my AMD64 this takes 2 seconds: this is a transaction rate 
> of 500K/sec. This easy solves the so-called '10K' problem, in 
> fact it makes it into a joke.

Why not go for the summit, then?  ;-)

http://www.erlang.org/pipermail/erlang-questions/2005-November/017740.ht
ml

I ran 20M simultaneous Erlang processes on a 16GB Sun,
with constant-time context switch and message passing.
(After that, I ran out of memory. The hard-coded limit
is 134,217,727 processes. I've never had my hands on
a box with enough RAM to see what the practical limit
is.)

>From the Erlang camp, we expressed our frustration with
the concurrency tests in the shootout, since they didn't,
in our opininon test real scalability. The response was 
that if they had set the limit to something considerably
higher than 5000 threads, many of the entries would have
been non-starters. Well, pooh.

In our commercial systems, 5000 simultaneous processes
is considered a comfortable amount of concurrency. We
do have some concerns about building live systems with
hundreds of thousand processes - and they are mostly 
about debugging. Some popular debugging commands print
meta-data for all active processes to the tty, and 
doing so on a live system with hundreds of thousand
processes would most certainly kill it, unless we had
sufficient guards or throttles in place.

It's not (just) a bragging point. In our experience, 
people start modeling for massive concurrency only
when they feel really sure that processes/threads
are _cheap_, and that the system can handle it -
and not only on a sunny day. Until then, processes
are treated as a scarce resource, and programmers 
will jump through hoops trying to limit the 
amount of concurrency. This is practically always
a _very_ bad idea, and the main reason why
concurrency has a bad rep, IMO.

BR,
Ulf W

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