In this issue

Tarballs were created this week for a 2.0.37 release, but at the last minute a problem in the handling of HEAD requests was discovered, causing the server to hang rather than sending the response (on some operating systems). A fix was quickly committed, and the 2.0.37 release was abandoned; testing is now underway for a 2.0.38 release.

Discussion continued from last week on PHP performance issues in Apache 2.0, a major concern being the buffering of script output. In 1.3, the output of a PHP script was buffered internally by Apache before being sent to the client, meaning that a smaller number of system calls were used to send the data. Currently in 2.0 the PHP filter module uses the non-buffering interface to the filter stack, resulting in a large number of system calls each writing small amounts of data. A workaround for this problem is to enable PHP's internal buffering setting the output_buffering configuration variable; a proposal was made to change the PHP filter to use the buffered write interface by default.

In this section we highlight some of the articles on the web that are of interest to Apache users.

Developer Shed explores a significant facet of the Apache web server in "Using Apache As A Proxy Server". It kicks off by explaining about the functions of a proxy server, and then provides the instructions for compiling, installing, and configuring both Apache 1.3 and Apache 2.0 as a proxy server and also as a reverse proxy server. It also shows you how to enable the proxy caching feature.

In "Parsing and Summarizing a Logfile", Randal L. Schwartz walks you through a tool which he wrote using Perl, for analysing how many hits are being cached and delivered by a stripped-down Apache server which acts as a caching reverse proxy server. For this to work, the access log file need to store caching information. This is implemented by using the CustomLog and LogFormat directives.

This article looks at another custom caching solution which is used to scale a dynamic content management system. It uses ColdFusion Web Application Server 5.0, and Apache as the Web server on Windows 2000 to illustrate its points but the underlying technique could be applied to any platform and software.

Chapter 4 ("Performance Monitoring") of the book, "Web Performance Tuning, 2nd Edition" by Patrick Killelea defines the parameters of performance and shows you a few methods on measuring and monitoring it. Apache is used in the example for setting up a version of ps that can be accessed from the Web.