Last modified: 2013-01-29 18:48:15 UTC
MediaWiki 1.17.0 PHP 5.3.8-1~dotdeb.2 (cgi-fcgi) MySQL 5.1.58-1~dotdeb.1 In /includes/Webstart.php, starting at line 132: # Initialise output buffering # Check that there is no previous output or previously set up buffers, because # that would cause us to potentially mix gzip and non-gzip output, creating a # big mess. if ( !defined( 'MW_NO_OUTPUT_BUFFER' ) && ob_get_level() == 0 ) { require_once( "$IP/includes/OutputHandler.php" ); ob_start( 'wfOutputHandler' ); } The output handler is not initialized if ob_get_level() != 0. As a consequence, gzip content encoding would not be enabled. The problem is that ob_get_level() will always return 1 or more if you have output buffering enabled in php.ini (output_buffering is false by default, but PHP suggests a production value of 4096), which means that basically every PHP script starts with ob_start(). One solution to this problem would be to remove the default output buffer early when Mediawiki starts: while(ob_get_level() > 0){ ob_end_clean(); } If this is undesired, and if the conditional check in Webstart is not changed, at the least, mediawiki setup should show a warning notice that with the given output_buffering setting, its output handler (i.e. gzip handler) won't be executed.
Code has slightly changed /includes/WebStart.php , but still valid in 1.21wmf8: wfProfileIn( 'WebStart.php-ob_start' ); # Initialise output buffering # Check that there is no previous output or previously set up buffers, because # that would cause us to potentially mix gzip and non-gzip output, creating a # big mess. if ( !defined( 'MW_NO_OUTPUT_BUFFER' ) && ob_get_level() == 0 ) { if ( !defined( 'MW_COMPILED' ) ) { require_once( "$IP/includes/OutputHandler.php" ); } ob_start( 'wfOutputHandler' ); } Similar comments in http://stackoverflow.com/questions/3641598/ob-get-level-starts-at-level-1 Docs: http://php.net/manual/en/function.ob-get-level.php
