While playing with memcached I wanted to find a way to monitor what was getting set. You see, we are trying to pre-warm our cache with lots of colours. (roughly 16.5 million of them 
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Anyway, I remembered I’d had a play a (long) while ago with expect and decided it would be just the thing…
So here we are – a status report from memcached every 5 minutes.
#!/bin/bash
# script to monitor memcached
expect << EOF
set timeout 1
spawn telnet localhost 11211
while 1 {
send "stats\n";
expect #
send "stats slabs\n";
expect #
puts "sleeping for 5 mins"
sleep 300;
}
# ends
Our pre_warming script has been running for almost an hour and has warmed the cache with 319116 items – so about 52 hours to go….
In terms of memory usage, I am running memcached with a Gig of Ram, and after the hour we are only using 4.7 meg of that . So my estimate is that we would need approximately 250MB.
Target = 16,581,375 items (colours) 1 hour = 319,116 items 1 hour = 5,005,741 bytes written so 16,581,375/319,116 = 51.96 Hours so 5,005,741*51.96 = 260,098,302 bytes = 248.05 MB
And now I’ve done these calculations, something makes me want to revist my memcache monitor script so that I pass it a target and then get a “time left” estimate
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).