Conference bulova::decw_jan-89_to_nov-90

What's your SYSGEN parameter MAXPROCESSCNT set to?  The default
is 32.

		Steve

    When you are using the DECNET transport, be aware of the NCP parameter
    MAXLINKS.  I think it defaults to 32.  
    
    Of course, MAXLINKS doesn't come into play when you are using the LOCAL
    transport...
    
    
    John B.

    I think the V1 Xlib has a restriction to 32 connections, and that it's
    been relaxed in V2.  Maybe Vince or Burns will confirm it for me.

    I think that the limitation is actually in the server.  There are
    certainly places where a longword is used with one bit per connection,
    and given that we're using 32 bit machines, that limits things to 32
    connections.
    
    James

James is correct, the limitation in both DECwindows V1.0 and V2.0 is
32 connections for the server.  This means that at most 32 independent
applications can access the server, no matter what type of transport
is used.  Note that once an application opens a display, it can create
as many windows with that same display as it wants (subject to memory
contraints of course).

We can certainly consider raising this limit in the next version.
Could you tell me what 32 applications you are running?  How many
simultaneous application invocations do you eventually want to run?

    Well, I'm  not  really  sure  if  there  should  be  a  MAXIMUM number,
    expecially if it  is  less  than  100.  By the time you get DECterms on
    four or five systems, bookreader, fileview,  mail, the other OOTBs that
    are  useful  and who knows what other  applications  (session  manager,
    xload,  window  manger, banner, xfish, xrn, and DECwrite  all  come  to
    mind)  you've eaten quite a few connections to the  server.    I  count
    seventeen different applications  (with  independent connections) on my
    screen right now.
    
    The bottom line is that the customer can't tell us up front the maximum
    number of connections - he'll eventually hit any limit we impose.
    
    I  understand  there  are  most  likely  tradeoffs  that  must  be made
    regarding  resource  usage.    Perhaps this limit needs to be a tunable
    sysgen parameter?
    
    James McCartney
    DECforms
    

I understand that eventually customers will want to exceed the 32
connections per server limit.  The limit is not there because of
resource issues.  The limit is because of a design restriction in
the server, which can be removed by a (relatively) small redesign.

However, there may be a resource issue once the restriction is lifted:
each connection will use 171 global pages per local connection.  If
you hit the limit of 32 connections today, you will be using 32*171
global pages, or 5472 pages.

So to rephrase my questions, how soon will customers want to exceed
the 32 connection per server limit in practice?  And here's a harder
question: for a given CPU speed and memory size, how many connections
should the server support at a minimum?

If you have any good rules of thumb, please post them... thanks!

It appears that local transport connections are limited
to 16 (15 plus my session manager?).  Is there any way
to increase this to a higher value?  Also, is there a
way to redefine the default transport to LOCAL or 
specify the preferred transport? I have noticed that
the default transport logical nolonger is defined.  

I have a customer who is using atleast 17 connections
of his own. So with V2, we must do some of the connects
with DECnet.  This is very expensive when it comes to
performance.  Although we are trying to convince the
customer to use many less connections, they currently
are going their own direction. I'm sure as time goes
on, they will want even more connections.

As far as limits go,  if we lift the upper limit and
document the cost per connection, this would help the
field recommend better solutions to our customers, yet
allow the customers to still do it thier way.  With the
limits, the customers preceive that we are once again
trying to force them into our way of thinking, even 
when we have a better solution.

    While LOCAL transport doesn't place a limit on the maximum number of
    connections, it does use a resource, locks, which are limited by a
    quota.  In particular, it uses two per connection.
    
    The ENQLM quota has a default value of 30, and this is not currently
    overridden in SYS$MANAGER:DECW$STARTSERVER.COM.  Thus, we have an
    effective limit of 15 local connections.
    
    If you need to fix this immediately (i.e. before I fix it on the master
    pack and it ships), then you should probably add a line that looks like
    
    	/ENQUEUE_LIMIT = 64 -
    
    to SYS$MANAGER:DECW$STARTSERVER.COM where the RUN/DETACHED is (at the
    end of the file).
    
    
    James