Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!haven!decuac!felix!martin
From: martin@felix.UUCP (Martin McKendry)
Newsgroups: comp.unix.questions
Subject: Shared Libraries -- experiences etc.
Message-ID: <81584@felix.UUCP>
Date: 31 Jan 89 00:05:21 GMT
Sender: daemon@felix.UUCP
Reply-To: martin@felix.UUCP (Martin McKendry)
Organization: FileNet Corp., Costa Mesa, CA
Lines: 36


I have a couple of questions about System V implementations
and other Unix systems that implement shared libraries.  Since
the answers will reflect system dependencies, and we are 
designing for maximum portability, I'd be interested in
answers for any systems, but particularly for the better known
ones -- Suns, 3B2's, Unisys boxes (Convergent?), etc.

    o) What is the maximum size of a process?  Text space
       and data space.

    o) How many semaphores are allowed?

    o) What tools exist for allocating portions of the address
       space among shared libraries?  How much space is there?

    o) How useful have shared libraries proven in practice for
       implementing complex applications?  Are other techniques
       or combinations of features more useful?

    o) Are semaphores the only appropriate technique for implementing
       mutual exclusion on small objects?  For example, if I had a
       large number (say, 2000) of objects that were small (say, 20 bytes),
       and I wanted to put locks on each object.  Assume that there
       are many processes active in the total structure, but they
       tend not to interfere with one another.  Are semaphores the
       mechanism of choice for this problem?  It seems like a lot
       of overhead to allocate one semaphore per record.

Any answers or input appreciated.

Martin McKendry

--
Martin S. McKendry;    FileNet Corp;	{hplabs,trwrb}!felix!martin
Strictly my opinion; all of it