Apache::VMonitor -- The Visual System and Apache Server Monitor Page 2

You should load the module in httpd.conf:

  PerlModule Apache::VMonitor

Or from the the startup file:

  use Apache::VMonitor();

You can alter the monitor reporting behavior, by tweaking the following configuration arguments from within the startup file:

  ::VMonitor::Config{BLINKING} = 1;
  ::VMonitor::Config{REFRESH}  = 0;
  ::VMonitor::Config{VERBOSE}  = 0;

You can control what sections are to be displayed when the tool is first accessed via:

  ::VMonitor::Config{SYSTEM}   = 1;
  ::VMonitor::Config{APACHE}   = 1;
  ::VMonitor::Config{PROCS}    = 1;
  ::VMonitor::Config{MOUNT}    = 1;
  ::VMonitor::Config{FS_USAGE} = 1;

You can control the sorting of the mod_perl processes report. You can sort them by one of the following columns: ''pid'', ''mode'', ''elapsed'', ''lastreq'', ''served'', ''size'', ''share'', ''vsize'', ''rss'', ''client'', ''request''. For example to sort by the process size the following setting will do:

  ::VMonitor::Config{SORT_BY}  = "size";

As the application provides an option to monitor other than mod_perl processes, you may set a regular expression to match the wanted processes. For example to match the process names which include httpd_docs, mysql and squid string, the following regular expression is to be used:

  ::VMonitor::PROC_REGEX = join "\|", qw(httpd_docs mysql squid);

We will discuss all these configuration options and their influence on the application shortly.

Multi-processes and system overall status reporting mode

The first mode is the one that mainly used, since it allows you to monitor almost all important system resources from one location. For your convenience you can turn on and off different sections on the report, to make it possible for reports to fit into one screen.

This mode comes with the following features.

Automatic Refreshing Mode
You can tell the application to refresh the report every few seconds. You can preset this value at the server startup. For example to set the refresh to 60 seconds you should add the following configuration setting:
  ::VMonitor::Config{REFRESH} = 60;

A 0 (zero) value turns automatic refreshing off.

When the server is started you can always adjust the refresh rate using the application user interface.

top(1) Emulation: System Health Report
Just like top(1) it shows current date/time, machine up-time, average load, all the system CPU and memory usage: CPU load, Real memory and swap partition usage.

The top(1) section includes a swap space usage visual alert capability. As we know swapping is very undesirable on production systems. The system is said to be swapping, when it has used all of its RAM and starts to page out unused memory pages to the slow swap partition which slows the whole system down and may eventually lead to the machine crush.

This article was originally published on Dec 27, 2000

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