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
      <Location /system/vmonitor>
        SetHandler perl-script
        PerlHandler Apache::VMonitor
      </Location>

      # startup file or <Perl> 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:

      <Location /system/vmonitor>
        SetHandler perl-script
        PerlHandler Apache::VMonitor
      </Location>

    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:

      <Location /system/vmonitor>
        SetHandler perl-script
        PerlHandler Apache::VMonitor
        order deny, allow
        deny  from all
        allow from 132.123.123.3
      </Location>

    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 "<Perl>" 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 <stas@stason.org>

COPYRIGHT
    The Apache::VMonitor module is free software; you can redistribute it
    and/or modify it under the same terms as Perl itself.