The following reply was made to PR general/1428; it has been noted by GNATS.
From: Marc Slemko <[EMAIL PROTECTED]>
To: Apache bugs database <[EMAIL PROTECTED]>
Cc: Subject: Re: general/1428: Increasing number of non-IP virtual hosts
drastically increases memory demands (fwd)
Date: Tue, 18 Nov 1997 14:43:08 -0700 (MST)
---------- Forwarded message ----------
Date: Tue, 18 Nov 1997 16:28:32 -0500
From: Brian Atkins <[EMAIL PROTECTED]>
To: Marc Slemko <[EMAIL PROTECTED]>
Subject: Re: general/1428: Increasing number of non-IP virtual hosts
drastically increases memory demands
Marc Slemko wrote:
>
> On 18 Nov 1997, Brian Atkins wrote:
>
> > A followup on this critical bug: The same behavior has been
> > observered in 1.3b2. Both grow to over 50MEGs of malloc'ed
> > mem when using 1250 or so non-IP virtual hosts. After about
> > that many, neither of them will even start up (even with all
> > shell limits unlimited), failing with the error:
> > "Ouch! malloc failed in malloc_block()"
>
> Most of that memory is shared between processes on any reasonable OS, ie.
> you only have one copy of it. Many systems, however, still expect you to
> have enough swap to allocate swap so that you would have enough if they
> were all different.
>
> >
> > As long as this problem remains, the promise of non-IP hosting
> > will not be realized, and ISPs will remain shackled to having
> > a small number of virtual domains per physical NIC/server.
> > Steps should be taken to fix the problem, and to allow Apache
> > to host a minimum of 10,000 non-IP domains.
>
> Say you needed 2k of data structures for each virtual domain. That is
> perfectly reasonable. Then you will still need 20 megs per process for
> 10000 non-IP virtual hosts. You are likely using it in a very
> specialized application: you probably have nearly identical config
> settings for each vhost. There is going to be overhead per virtual host.
> You would need to modify Apache specifically for your setup if you wanted
> to
Well, I know a little C but am by no means good enough to modify
the Apache source... I really don't see where all the mem is going
though- we have very minimal virtual host definitions, just a
server name, IP, document root, and a cgi-bin scriptalias. Seems
like all that together would be less than 500 bytes?
>
> A virtual server is just that: a virtual server, configurable nearly as
> much as the main server. That takes overhead. Hostnames aren't really
> good substitutions for directories.
Well, would it be possible to create something like "lite" virtual
hosts that could be a lot more memory efficient?
>
> You may be able to scrap all the vhosts, keep the hostnames, then use
> mod_rewrite to internally rewrite user.domain to domain/user or
> domain/~user or whatever. Would have to think about that one.
That really would be unacceptable...
>
> There are a few more things to be said about this WRT how copy on write is
> working in this situation, how it would be nice if it worked, and what
> Apache could do to work around it, but I don't have time right now. I
> will comment more later.
I'd appreciate any help or further advice you might have. Thanks
--
The future has arrived; it's just not evenly distributed.
-William Gibson
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