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The Correct Way To Set Up gzip with Magento

We wrote this arti­cle in response to post­ings offer­ing advice to users of Magento, an open source ecom­merce sys­tem. The advice is being given with good inten­tions, and the intent is only to assist their fel­low Magento users. But the advice being give may actu­ally have the poten­tial cause harm to the users site, or at the least a good deal of down time. The advice being offered is to help speed up Magento by enabling a server side caching sys­tem called gzip. What peo­ple don’t real­ize is that their being told to enable two sep­a­rate caching sys­tems. These two sys­tems tend not to play well together, and could cause harm to your install. While most peo­ple see pos­i­tive results, there are a rare few see­ing server side errors, data­base errors, and are stumped as to why.

The two caching sys­tems are gzip and zlib. Most rep­utable host­ing com­pa­nies include these options in their shared host­ing pack­ages. By default most of these options are dis­abled. We’re going to show you the right way to setup caching on your server, and at the same time solve the dreaded recur­ring mem­ory issues that have plagued so many Magento users. Our setup is as fol­lows. A shared host­ing account on Hostmonster.com, a fresh Magento install, cur­rently the lat­est ver­sion 1.3.2.4. and the gzip caching.

The major­ity of peo­ple read­ing this will be on a sim­i­lar shared host­ing account, so this will be our focus. If you don’t already know whether gzip is avail­able on your server, copy the fol­low­ing code to an html edi­tor, or a text edi­tor, and save it as test.php

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<?php
phpinfo();
?>

Upload the file to your server, and nav­i­gate to it with your web browser. If you see gzip any­where on the info page, you’re in luck. Remem­ber to remove this file before mov­ing on, as it does pose a secu­rity threat if left on the server.

Next you need to log into you host­ing account and access your cpanel. Keep in mind that most good host­ing com­pa­nies will help you with all of this, so never be ashamed to ask for help.

Before going any fur­ther, you should also be absolutely pos­i­tive that all your sites can run on PHP5. If not you’ll want to upgrade any scripts uti­liz­ing an older ver­sion of php. Now we need to install a sin­gle default ini, php.ini.default, via your cpanel. Nav­i­gate to the the php admin area. Choose to install a (Sin­gle php.ini) Choose save, then scroll down to the check­boxes for Ion­Cube and Source­Guardin, and click “Install php.ini Mas­ter File”. This man­u­ally directs sys­tem resources to the new loca­tion of your sin­gle php.ini file. Call your host if you need help. Now down­load the file that was just cre­ated from the root direc­tory of your server ( php.ini.default ) Rename this file to php.ini and open it.

First locate the mem­ory set­tings, cur­rently located on line 225, and dupli­cate the set­ting bel­low. Your loca­tion may vary. Note, the char­ac­ter # before a state­ment means that won’t be read by the server, and has been “com­mented out”.

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;;;;;;;;;;;;;;;;;;;
; Resource Limits ;
;;;;;;;;;;;;;;;;;;;
 
max_execution_time = 60     ; Maximum execution time of each script, in seconds
max_input_time = 120	; Maximum amount of time each script may spend parsing request data
memory_limit = 128M      ; Maximum amount of memory a script may consume (64MB)

Change the default mem­ory from the whop­ping default of 32m to a min­i­mum of 64m in a busy envi­ron­ment, or prefer­ably to some­thing like 128m, or even 256m if run­ning a siz­able store on a stand­alone server. Set­ting the ram too high can lead to sys­tem insta­bil­ity, loss of per­for­mance, and even a loss of priv­i­lege stem­ming from an inter­ven­tion by your sys­tem admins. With this ini in place, you’ve now set a global mem­ory set­ting across all fold­ers on your server. This is a sure fire way to elim­i­nate freez­ing dur­ing check­out, and other ran­dom Magento weirdness.

While here, you may also want to increase server exe­cu­tion time. While not nec­es­sary, espe­cially with our now increased Ram, our sug­ges­tion would be to dou­ble or triple the cur­rent set­tings. If you’ve got a script run­ning longer than a few min­utes, there’s prob­a­bly some­thing wrong, and a forced stop is in order.

Now that we’re uti­liz­ing more mem­ory, and have improved over­all sta­bil­ity and reli­a­bil­ity, it’s time to really make this thing boo­gie. With our default php.ini still open, search for ob_gzhandler This is also an area where you’ll see the use of either gzip or zlib, and never both. At the time of this tuto­r­ial the state­ment we’re inter­ested in uncom­ment­ing is located on line 106. Your loca­tion may vary. Note, like # in our .htac­cess, ; means that any state­ment fol­low­ing this char­ac­ter isn’t read by the server, and is “com­mented out”.

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; Output buffering allows you to send header lines (including cookies) even
; after you send body content, at the price of slowing PHP's output layer a
; bit.  You can enable output buffering during runtime by calling the output
; buffering functions.  You can also enable output buffering for all files by
; setting this directive to On.  If you wish to limit the size of the buffer
; to a certain size - you can use a maximum number of bytes instead of 'On', as
; a value for this directive (e.g., output_buffering=4096).
output_buffering = Off
 
; You can redirect all of the output of your scripts to a function.  For
; example, if you set output_handler to "mb_output_handler", character
; encoding will be transparently converted to the specified encoding.
; Setting any output handler automatically turns on output buffering.
; Note: People who wrote portable scripts should not depend on this ini
;       directive. Instead, explicitly set the output handler using ob_start().
;       Using this ini directive may cause problems unless you know what script 
;       is doing.
; Note: You cannot use both "mb_output_handler" with "ob_iconv_handler"
;       and you cannot use both "ob_gzhandler" and "zlib.output_compression". 
output_handler = ob_gzhandler
 
; Transparent output compression using the zlib library
; Valid values for this option are 'off', 'on', or a specific buffer size
; to be used for compression (default is 4KB)
; Note: Resulting chunk size may vary due to nature of compression. PHP 
;       outputs chunks that are few hundreds bytes each as a result of 
;       compression. If you prefer a larger chunk size for better 
;       performance, enable output_buffering in addition.
; Note: You need to use zlib.output_handler instead of the standard
;       output_handler, or otherwise the output will be corrupted.
zlib.output_compression = Off
 
; You cannot specify additional output handlers if zlib.output_compression
; is activated here. This setting does the same as output_handler but in
; a different order.
;zlib.output_handler =

Notice here that zlib is either com­mented out, or off. Be sure it stays this way.

Some­thing else worth men­tion­ing is the addi­tion of the fol­low­ing state­ments to your ini file. As of this tuto­r­ial, the fol­low­ing state­ments were added to our php.ini by default. But if your host­ing provider isn’t as proac­tive, they may be miss­ing. If so add them some­where near the bot­tom of your ini file as follows.

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extension=pdo.so
extension=pdo_sqlite.so
extension=sqlite.so
extension=pdo_mysql.so

We’ve now fin­ished edit­ing our PHP.ini. Upload the file back to the root of your server. This one file pro­vides the sin­gle largest per­for­mance and sta­bil­ity improve­ment you’ll find with Magento.

Next retrieve your .htac­cess file from the root of your Magento install. Dupli­cate the set­tings you see below, and again upload the file back to the root of your server.
Mem­ory settings:

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############################################
## adjust memory limit
 
#    php_value memory_limit 64M
    php_value memory_limit 128M
    php_value max_execution_time 18000
 
############################################

GZip uti­liza­tion:

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############################################
## enable apache served files compression
## http://developer.yahoo.com/performance/rules.html#gzip
 
    # Insert filter on all content
    SetOutputFilter DEFLATE
    # Insert filter on selected content types only
    AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css text/javascript
 
    # Netscape 4.x has some problems...
    BrowserMatch ^Mozilla/4 gzip-only-text/html
 
    # Netscape 4.06-4.08 have some more problems
    BrowserMatch ^Mozilla/4\.0[678] no-gzip
 
    # MSIE masquerades as Netscape, but it is fine
    BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
 
    # Don't compress images
    SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png)$ no-gzip dont-vary
 
    # Make sure proxies don't deliver the wrong content
    Header append Vary User-Agent env=!dont-vary
 
</IfModule>
 
<IfModule mod_ssl.c>
 
############################################

Also look at the top of your .htac­cess file. If you don’t see the fol­low­ing, and you’re sure you’ve setup your server to use a sin­gle php.ini by default, add the following.

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# Use PHP5 Single php.ini as default
AddHandler application/x-httpd-php5s .php
############################################
## uncomment these lines for CGI mode
## make sure to specify the correct cgi php binary file name
## it might be /cgi-bin/php-cgi
 
#    Action php5-cgi /cgi-bin/php5-cgi
#    AddHandler php5-cgi .php
 
############################################

This would be a good time to remove any extra php.ini or .htac­cess files you’ve loaded to mis­cel­la­neous direc­to­ries in an attempt to improve Magento’s sta­bil­ity, some­thing we our­selves were guilty of.

And that’s it, within a minute of upload­ing your .htac­cess file you’ll be serv­ing, gziped files with a com­pres­sion ratio of 70–90 per­cent. Be sure to check that all scripts being served prop­erly, and are func­tion­ing nor­mally. Com­pres­sion may cause some scripts to behave errat­i­cally, or even cause pages to load jum­bled con­tent. To find out exactly what your com­pres­sion ratio is, visit any of the sites below and input your web­site url.

GZip Test­ing Sites

1. GZip Dis­crim­i­na­tion Test
2. Whatsmyip

We hope this arti­cle was help­ful, and if you think we’ve missed any­thing, let us know. Thanks for stop­ping by.