NAME
Apache::VMonitor - Visual System and Apache Server Monitor
SYNOPSIS
# mod_status should be compiled in (it is by default)
ExtendedStatus On
# Configuration in httpd.conf
SetHandler perl-script
PerlHandler Apache::VMonitor
# startup file or section:
use Apache::VMonitor();
$Apache::VMonitor::Config{BLINKING} = 1;
$Apache::VMonitor::Config{REFRESH} = 0;
$Apache::VMonitor::Config{VERBOSE} = 0;
$Apache::VMonitor::Config{SYSTEM} = 1;
$Apache::VMonitor::Config{APACHE} = 1;
$Apache::VMonitor::Config{PROCS} = 1;
$Apache::VMonitor::Config{MOUNT} = 1;
$Apache::VMonitor::Config{FS_USAGE} = 1;
$Apache::VMonitor::Config{SORT_BY} = 'size';
$Apache::VMonitor::PROC_REGEX = join "\|", qw(httpd mysql squid);
DESCRIPTION
This module emulates the reporting functionalities of top(1), extended
for mod_perl processes, mount(1), and df(1) utilities. It has a visual
alerting capabilities and configurable automatic refresh mode. All the
sections can be shown/hidden dynamically through the web interface.
The are two main modes:
* Multi processes mode
All system processes and information are shown. See the detailed
description of the sub-modes below.
* Single process mode
If you need to get an indepth information about a single process,
you just need to click on its PID.
If the chosen process is a mod_perl process, the following info is
displayed:
* Process type (child or parent), status of the process
(*Starting*, *Reading*, *Sending*, *Waiting*, etc.), how long
the current request is processed or the last one was processed
if the process is inactive at the moment of the report take.
* How many bytes transferred so far. How many requests served per
child and per slot.
* CPU times used by process: "total", "utime", "stime", "cutime",
"cstime".
For all (mod_perl and non-mod_perl) processes the following
information is reported:
* General process info: UID, GID, State, TTY, Command line
arguments
* Memory Usage: Size, Share, VSize, RSS
* Memory Segments Usage: text, shared lib, date and stack.
* Memory Maps: start-end, offset, device_major:device_minor,
inode, perm, library path.
* Loaded libraries sizes.
Just like the multi-process mode, this mode allows you to
automatically refresh the page on the desired intervals.
Other available modes within 'Multi processes mode'.
refresh mode
From within a displayed monitor (by clicking on a desired refresh
value) or by setting of $Apache::VMonitor::Config{REFRESH} to a
number of seconds between refreshes you can control the refresh
rate. e.g:
$Apache::VMonitor::Config{REFRESH} = 60;
will cause the report to be refreshed every single minute.
Note that 0 (zero) turns automatic refreshing off.
top(1) emulation (system)
Just like top(1) it shows current date/time, machine uptime, 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. The color of the swap report will be changed:
swap usage report color
---------------------------------------------------------
5Mb < swap < 10 MB light red
20% < swap (swapping is bad!) red
70% < swap (almost all used!) red + blinking (if enabled)
Note that you can turn off blinking with:
$Apache::VMonitor::Config{BLINKING} = 0;
The module doesn't alert when swap is being used just a little
(<5Mb), since it happens most of the time, even when there is plenty
of free RAM.
If you don't want the system section to be displayed set:
$Apache::VMonitor::Config{SYSTEM} = 0;
The default is to display this section.
top(1) emulation (Apache/mod_perl processes)
Then just like in real top(1) there is a report of the processes,
but it shows all the relevant information about mod_perl processes
only!
The report includes the status of the process (*Starting*,
*Reading*, *Sending*, *Waiting*, etc.), process' ID, time since
current request was started, last request processing time, size,
shared, virtual and resident size. It shows the last client's IP and
Request URI (only 64 chars, as this is the maximum length stored by
underlying Apache core library).
You can sort the report by any column, see the CONFIGURATION section
for details.
The section is concluded with a report about the total memory being
used by all mod_perl processes as reported by kernel, plus extra
number, which results from an attempt to approximately calculate the
real memory usage when memory sharing is taking place. The
calculation is performed by using the following logic:
1 For each process sum up the difference between shared and total
memory.
2 Now if we add the share size of the process with maximum shared
memory, we will get all the memory that is actually used by all
mod_perl processes, but the parent process.
Please note that this might be incorrect for your system, so you
should use this number on your own risk. We have verified this
number on the Linux OS, by taken the number reported by
"Apache::VMonitor", then stopping mod_perl and looking at the system
memory usage. The system memory went down approximately by the
number reported by the tool. Again, use this number wisely!
If you don't want the mod_perl processes section to be displayed
set:
$Apache::VMonitor::Config{APACHE} = 0;
The default is to display this section.
top(1) emulation (any processes)
This section, just like the mod_perl processes section, displays the
information in a top(1) fashion. To enable this section you have to
set:
$Apache::VMonitor::Config{PROCS} = 1;
The default is not to display this section.
Now you need to specify which processes are to be monitored. The
regular expression that will match the desired processes is required
for this section to work. For example if you want to see all the
processes whose name include any of these strings: *http*, *mysql*
and *squid*, the following regular expression is to be used:
$Apache::VMonitor::PROC_REGEX = join "\|", qw(httpd mysql squid);
mount(1) emulation
This section reports about mounted filesystems, the same way as if
you have called mount(1) with no parameters.
If you want the mount(1) section to be displayed set:
$Apache::VMonitor::Config{MOUNT} = 1;
The default is NOT to display this section.
df(1) emulation
This section completely reproduces the df(1) utility. For each
mounted filesystem it reports the number of total and available
blocks (for both superuser and user), and usage in percents.
In addition it reports about available and used file inodes in
numbers and percents.
This section has a capability of visual alert which is being
triggered when either some filesystem becomes more than 90% full or
there are less than 10% of free file inodes left. When this event
happens the filesystem related report row will be displayed in the
bold font and in the red color. A mount point directory will blink
if the blinking is turned on. You can turn the blinking on with:
$Apache::VMonitor::Config{BLINKING} = 1;
If you don't want the df(1) section to be displayed set:
$Apache::VMonitor::Config{FS_USAGE} = 0;
The default is to display this section.
abbreviations and hints
The monitor uses many abbreviations, which might be knew for you. If
you enable the VERBOSE mode with:
$Apache::VMonitor::Config{VERBOSE} = 1;
this section will reveal all the full names of the abbreviations at
the bottom of the report.
The default is NOT to display this section.
CONFIGURATION
To enable this module you should modify a configuration in httpd.conf,
if you add the following configuration:
SetHandler perl-script
PerlHandler Apache::VMonitor
The monitor will be displayed when you request
http://localhost/system/vmonitor or alike.
You probably want to protect this location, from unwanted visitors. If
you are accessing this location from the same IP address, you can use a
simple host based authentication:
SetHandler perl-script
PerlHandler Apache::VMonitor
order deny, allow
deny from all
allow from 132.123.123.3
Alternatively you may use the Basic or other authentication schemes
provided by Apache and various extensions.
You can control the behavior of this module by configuring the following
variables in the startup file or inside the "" section.
Module loading:
use Apache::VMonitor();
Monitor reporting behavior:
$Apache::VMonitor::Config{BLINKING} = 1;
$Apache::VMonitor::Config{REFRESH} = 0;
$Apache::VMonitor::Config{VERBOSE} = 0;
Control over what sections to display:
$Apache::VMonitor::Config{SYSTEM} = 1;
$Apache::VMonitor::Config{APACHE} = 1;
$Apache::VMonitor::Config{PROCS} = 1;
$Apache::VMonitor::Config{MOUNT} = 1;
$Apache::VMonitor::Config{FS_USAGE} = 1;
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:
$Apache::VMonitor::Config{SORT_BY} = 'size';
A regex to match processes for 'PROCS' section:
$Apache::VMonitor::PROC_REGEX = join "\|", qw(httpd mysql squid);
Read the DESCRIPTION section for a complete explanation of each of these
variables.
DYNAMIC RECONFIGURATION
"Apache::VMonitor" allows you to dynamically turn on and off all the
sections and enter a verbose mode that explains each section and the
used abbreviations. These dynamic settings stored in the URI and not on
the server side.
PREREQUISITES
You need to have Apache::Scoreboard installed and configured in
*httpd.conf*, which in turn requires mod_status to be installed. You
also have to enable the extended status for mod_status, for this module
to work properly. In *httpd.conf* add:
ExtendedStatus On
Notice that turning the "ExtendedStatus" mode *On* is not recommended
for high-performance production sites, as it adds an overhead to the
request response times.
You also need Time::HiRes and GTop to be installed.
And of course you need a running mod_perl enabled apache server.
BUGS
TODO
I want to include a report about open file handlers per process to track
file handlers leaking. It's easy to do that by just reading them from
"/proc/$pid/fd" but you cannot do that unless you are root. "libgtop"
doesn't have this capability - if you come up with solution, please let
me know. Thanks!
SEE ALSO
Apache, mod_perl, Apache::Scoreboard, GTop
AUTHORS
Stas Bekman
COPYRIGHT
The Apache::VMonitor module is free software; you can redistribute it
and/or modify it under the same terms as Perl itself.