[ADMIN] pg-watchdog

[Mark Harrison]

Here is the final version of my script that will watch for disconnected
client machines and kill their associated server side processes.
If I'm doing anything really stupid I would appreciate hearing about it.
If it's useful to anyone, feel free to pass it along.
Thanks,
Mark
#!/bin/sh
# the next line restarts using wish \
exec tclsh8.3 "$0" "$@"
# pg-watchdog -- make sure postgres clients are reachable.
#
# This program is a watchdog for postgresql.  It monitors all
# postgresql client processes and kills them if the host upon
# which they are running becomes inaccessible over the network.
#
# This is necessary because if a machine goes down "hard" or
# if a network cable becomes disconnected, it can be several
# hours before postgres will be informed of this (for details,
# see chapter 23 of W. Richard Steven's TCP/IP Illustrated,
# volume 1).  If a postgres client on that machine has a
# transaction lock, all other clients will be blocked waiting
# for that lock to be released.
#
# This program uses the Scotty package available at:
#     http://wwwhome.cs.utwente.nl/~schoenw/scotty
# If you do not wish to install Scotty you can change
# the icmp command to instead use whatever flavor of
# ping is available on your system.
#
# Please send feedback, improvements, etc, to
# Mark Harrison, [EMAIL PROTECTED]
package require Tnm

proc doit {} {
    after 60000 doit
    set pids("") ""
    unset pids("")
    set lines [exec ps auxww | awk {$11=="postgres:" {print $2 "/" $14}}]
    foreach s [split $lines \n] {
        set x [split $s /]
        set pid [lindex $x 0]
        set ip  [lindex $x 1]
        if {[regexp {[0-9]+[.][0-9]+[.][0-9]+[.][0-9]+} $ip]} {
            lappend pids($ip) $pid
        }
    }
    if {[array size pids] > 0} {
        set times [icmp -timeout 20 echo [lsort [array names pids]]]
        foreach pair $times {
            set ip [lindex $pair 0]
            set time  [lindex $pair 1]
            if {$time == -1} {
                foreach pid $pids($ip) {
                    puts "killing $pid from $ip"
                    exec kill $pid
                }
            }
        }
    }
}
after 0 doit
vwait forever
--
Mark Harrison
Pixar Animation Studios
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