Apache::VMonitor -- The Visual System and Apache Server Monitor   

It's important to be able to monitor your production system's health. You want to monitor the memory and file system utilization, the system load, how much memory the processes use. Whether you aren't running out of swap space and more. All these tasks are feasible when one has an interactive (telnet/ssh/other) access to the box the web server is running on, but it's quite a mess since different Unix tools report about different parts of the system. Which means that you cannot watch the whole system at the same time and it requires lots of typing since one has to switch from one utility to another, unless many connections are open and then each terminal is dedicated to report about something specific.

But if you are running mod_perl enabled Apache server, you are in a good company, since it allows you to run a special module called Apache::VMonitor which provides most of the desired reports at once.

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  Finding a mod_perl provider or becoming one   

In this article we will talk about the nuances of providing mod_perl services and present a few ISPs that successfully do that.

• You installed mod_perl on your box at home, and you fell in love with it. So now you want to convert your CGI scripts (which currently are running on your favorite ISPs machine) to run under mod_perl. Then you discover that your ISP has never heard of mod_perl, or he refuses to install it for you.

• You are an old sailor in the ISP business, you have seen it all, you know how many ISPs are out there and you know that the sales margins are too low to keep you happy. You are looking for some new service almost no one else provides, to attract more clients to become your users and hopefully to have a bigger slice of the action than your competitors.

So if you are planning to become an ISP that provides mod_perl services or are just looking for such a provider this article is for you.

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  Getting Started with mod_perl in 30 minutes   

In the previous article, I've shown quite amazing web performance reports from companies that have deployed mod_perl heavily. You might be surprised but you can quite easily get similarly amazing results if you move your service to mod_perl as well. In fact, getting started with mod_perl shouldn't take you more than 30 minutes, the time it takes to compile and configure the server on a decent machine and get it running.

In this article I'll show step by step installation and configuration scenarios, and chances are you will be able to run the basic statically compiled mod_perl setup without reading any other documents. Of course you will want and need to read the documentation later, but I think you will agree with me that it's ultimately cool to be able to get your feet wet without knowing much about the new technology up-front.

The mod_perl installation was tested on many mainstream Unix platforms, so unless you have some very non-standard system you shouldn't have any problems when building the basic mod_perl server.

If you are a Windows user, the easiest way is to use the binary package available from http://perl.apache.org/distributions.html. From the same location you can download the Linux RPM version and CVS snapshots. However I recommend to always build the mod_perl from source, and as you will see in a moment, it's an easy thing to do.

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  Improving mod_perl Driven Site's Performance - Part 1: Choosing OS & Hardware   

In the next series of articles we are going to talk about mod_perl performance issues. We will try to look at as many aspects of the mod_perl driven service as possible. Hardware, software, Perl coding and finally the mod_perl specific aspects.

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  Improving mod_perl Driven Site's Performance - Part 2: Benchmarking Applications   

In this article we will talk about tools that we need to get armed with before we can start working on the performance of our service.

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  Improving mod_perl Driven Site's Performance - Part 3: Code Profiling & Memory Measurement Technique   

In this article we will continue the topic started in the previous article. This time we talk about tools that help us with code profiling and memory usage measuring.

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  Improving mod_perl Driven Site's Performance - Part 4: Forking & Executing Subprocesses from mod_per   

It's desirable to avoid forking under mod_perl. Since when you do, you are forking the entire Apache server, lock, stock and barrel. Not only is your Perl code and Perl interpreter being duplicated, but so is mod_ssl, mod_rewrite, mod_log, mod_proxy, mod_speling (it's not a typo!) or whatever modules you have used in your server, all the core routines, etc.

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  Improving mod_perl Driven Site's Performance - Part 4: Sharing Memory   

If your OS supports sharing of memory (and most sane systems do), you might save a lot of RAM by sharing it between child processes. This will allow you to run more processes and hopefully better satisfy the client, without investing extra money into buying more memory.

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  Improving mod_perl Driven Site's Performance - Part 5: Sharing Memory (continued)   

As we have learned in the previous article sharing memory helps us to save memory with mod_perl, which gives us a huge speed up but we pay with price of big memory foot print. I presented a few techniques to save memory by trying to share more of it. In this article we will see other techniques allowing you to save even more memory.

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  Improving mod_perl Driven Site's Performance - Part 7: Performance Tuning by Tweaking Apache Configu   

Correct configuration of the MinSpareServers, MaxSpareServers, StartServers, MaxClients, and MaxRequestsPerChild parameters is very important. There are no defaults. If they are too low, you will under-use the system's capabilities. If they are too high, the chances are that the server will bring the machine to its knees.

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