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From: jonathan@speedy.cs.pitt.edu (Jonathan Eunice)
Newsgroups: comp.unix.questions
Subject: Re: Is there a limit to create sockets on UNIX??
Message-ID: <8307@pitt.UUCP>
Date: 3 Aug 90 15:20:22 GMT
Sender: news@pitt.UUCP
Reply-To: jonathan@speedy.cs.pitt.edu (Jonathan Eunice)
Organization: University of Pittsburgh Computer Science
Lines: 31

Oops! 

In my recent comments on UNIX resource allocation, I said:

   While not widely delivered today, the clear trend is making UNIX
   resource allocation dynamically scalable.  A widespread interim
   solution is increasing the maximum limits. 

This much is true.  

Unfortunately, whilst upon my soapbox, I failed to see that I had
chosen precisely the wrong time/example to make the point.  The
per-process open file table is one that must be static, given the
necessary constraint of maintaining a fixed size u area (the area of 
user memory the kernel keeps to manage per-process data, such as open
files and sockets).  Other system resources (processes, shared memory
segments, per-system open files, etc) are controlled by tables that
live in memory that can be much more flexibly controlled.

The correct approach to per-process open files is indeed increasing the
maximum, static number.  SunOS, with its 256 limit, and especially AIX
3.1, with its 2,000 limit, have begun to move the figure above most any
potential problem.

Thanks to observant readers Carl Witty (cwitty@cs.stanford.edu) and Eduardo 
Krell (ekrell@ulysses.att.com) for their corrections.

Btw, I believe, but do not know, that Apollo's DomainOS has scalability
in the number of per-process open files.  DomainOS is built on an
internally-developed, production-oriented operating system base.  It
avoids many scalability problems common in traditional UNIX designs.