Hi Bill,
Thanks for taking the time to post your experiences.
It's a shame that so much time is spent tweaking, compiling,
testing, ferretting for bug references.
On Tue, 1 Jul 2003, Bill Marrs wrote:
>
> >That would be of my real interest to know as many details of Bill's
> >experience with mod_deflate as he can provide.
>
> Since I posted my first message, I've been snooping around the 'net to find
> more info on mod_gzip and mod_deflate. Here's what I came up with:
>
> The general recommendation seems to be migration from mod_gzip to
> mod_deflate when you switch to Apache 2.0. mod_gzip seems to have lost
> most of its support going forward while mod_deflate is part of the Apache
> source code and has active development.
>
> There is a Apache 2.0 compatible version of mod_gzip, here:
> http://www.gknw.de/development/apache/httpd-2.0/unix/modules/
>
> When I tried it, it didn't work for me. It caused my site to spit out
> blank pages and garbage. I had used my old Apache 1.3 mod_gzip config with
> it. I read that there's some odd timing issues where the Apache 2.0
> version of mod_gzip branched a long time ago and thus doesn't have some of
> the "modern" mod_gzip 1.3.x features. I didn't get config errors, though,
> just blanks and garbage. So, I decided to back away slowly for mod_gzip on
> Apache 2.0. There is more discussion of it here:
> http://freshmeat.net/projects/mod_gzip/?topic_id=90
>
> There a good mod_gzip info page here, though little is said about a 2.0
> version:
> http://www.schroepl.net/projekte/mod_gzip/index.htm
>
> The mod_gzip mailing list has some good info. Here's a 26 Jun 2003 post by
> someone who seems to know well what's going on (I think the author of the
> above page):
> Subject: [Mod_gzip] gzip vs deflate on Apache
> http://lists.over.net/pipermail/mod_gzip/2003-June/007130.html
>
>
> So, I decided to try harder to move ahead with mod_deflate. I'm using a
> built from scratch, Apache/2.0.46 mod_perl_1.99_09. Work is being done on
> mod_deflate, some recent directives has been added (I hear). One of which
> is DeflateCompressionLevel. Along with this addition in 2.0.44 came a
> better default for this compression level. It's now 6, the same thing that
> gzip and zlib uses by default. Apparently, it had been 1 before that,
> which is fast but doesn't compress very well. There's some discussion of
> this here:
> http://www.webcompression.org/deflate-compress.html
>
>
> My own personal experience with mod_deflate (in Apache/2.0.46) is that it
> tends to spike my server's load. My server (gametz.com) is dual 800Mhz,
> 1.5GB ram, Linux, doing about 70K pages/day. Last night, I happened to be
> watching it while the load jumped up a few points during my site's prime
> time, so I pulled mod_deflate out of the config file and that fixed it.
>
> So, today, I'm trying a lower DeflateCompressionLevel. I'm using 4 now
> (instead of the default 6). This seems better, though the load is still a
> little higher than it should be and I'm not quote at prime time
> yet. Still, I am getting decent compression. I'm going to keep an eye on
> it, I suspect I'll be at 3 later this evening.
>
> I never had any trouble with load when I used mod_gzip and Apache 1.3.
>
> The other odd problem I got was that if anywhere in my perl code I printed
> nothing (e.g. print "" or $foo="";print $foo), I'd get this error:
>
> error: 20014:Error string not specified yet at /my/perl/code.pl line 123
>
> This error was both blurted to the error_log and to the web page (screwing
> up the page and truncating further output).
>
> I changed my code to print " " instead of "" (HTML ignores extra
> white-space, so no biggie), and the errors all went away. So, I see this
> as an annoyance more than a serious bug.
>
> I really should try to tell the author of mod_deflate about these problems.
>
> Here's the config I'm using for mod_deflate:
>
> #####
> ## Deflate
> #####
> LoadModule deflate_module modules/mod_deflate.so
> AddOutputFilterByType DEFLATE text/*
> SetOutputFilter DEFLATE
>
> # Make sure proxies don't deliver the wrong content
> Header append Vary User-Agent env=!dont-vary
> DeflateBufferSize 8096
> # DeflateCompressionLevel 6
> DeflateCompressionLevel 4
> DeflateMemLevel 9
> DeflateWindowSize 15
> DeflateFilterNote Input instream
> DeflateFilterNote Output outstream
> DeflateFilterNote Ratio ratio
> LogFormat '"%r" %{outstream}n/%{instream}n (%{ratio}n%%) "%{User-agent}i"'
> defl\
> ate
> CustomLog /var/log/httpd/deflate_log deflate
>
> All of which I cribbed from the Apache 2.0 manual:
> http://httpd.apache.org/docs-2.0/mod/mod_deflate.html
>
>
> I sort of got forced into upgrading to Apache 2.0/mp2/etc. by RedHat. They
> announced they would pull support for old releases (all that used Apache
> 1.3) by the end of the year. Apparently, this may be an intentional
> (evil?) business move by them to motivate more customers to move to their
> Enterprise OS (which is very expensive, but has more stable software like
> good old Apache 1.3 & mp1).
>
> I did try to go back at one point, builing Apache 1.3 from source, but it
> had some other problem (maybe, because I used Perl 5.8.0?). But, then I
> waffled and decided there's also a lot of value in staying current. So,
> I'm back to 2.0 land, and I'm surviving so far.
>
> -=bill
>
>
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>
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>
--
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