Hi Bill, Thank you very much for the story. It makes sense. Just a couple of questions:
1. Are you using any Cascaded Stile Sheets and/of JavaScript libraries linked to your main web pages? 2. If yes, how do you turn compression off for those files in case of Netscape-4 originated request? Thanks, Slava ----- Original Message ----- From: "Bill Marrs" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, July 01, 2003 2:33 PM Subject: Re: Best compression for mod_perl application? > > >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 > > > > > > > > >
