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From Ryan Bloom <...@raleigh.ibm.com>
Subject Re: Shared memory in APR. (fwd)
Date Mon, 12 Jul 1999 11:08:27 GMT
> Hmmm.... you perhaps now that the reason why MM doesn't provide such shared
> memory segment _attachments_ from independent processes (a fork+exec according
> to shared memory is actually a independent process) is for portability
> reasons. Because MM uses 5 different shared memory implementations in the
> background and not all of them allow such attachments through unique ids from
> unrelated processes.

Yes, I know what the problem is.  That's why I am having a hard time
figuring out how to do it.

> 
> OTOH can you describe it in more detail why APR needs a shared memory model
> which works over fork/exec, Ryan? I've to admit that currently I'm wondering
> why this is really necessary...

This is necessary, because ANY non-unix-like platform requires it.
Windows doesn't have fork, it only has spawn.  The AS/400 doesn't have
fork.  OS/2 has fork, but it is really expensive, and it MIGHT make sense
to have OS/2 use spawn instead of fork.  APR is also supposed to be a
general Portable runtime, not an Apache-specific portable runtime.  It is
possible other programs might want a method for doing this.  I know, the
second argument isn't great, but it is ancillary.  The REAL reason we need
to be able to do this, is the platforms we are going to support which
don't have the option of using fork, or those where using fork is the
wrong decision.

Ryan

_______________________________________________________________________
Ryan Bloom		rbb@raleigh.ibm.com
4205 S Miami Blvd	
RTP, NC 27709		It's a beautiful sight to see good dancers 
			doing simple steps.  It's a painful sight to
			see beginners doing complicated patterns.	


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