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ajohnstone/memcached.key.distribution.test.php

Created October 15, 2011 16:24
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memcached.key.distribution.test.php
<?php
$nodes = array_filter(explode(' ',$_SERVER['argv'][1]));
$memcache = new Memcached;
//$memcache->setOption ( Memcached::OPT_DISTRIBUTION , Memcached::DISTRIBUTION_MODULA );
$memcache->setOption ( Memcached::OPT_DISTRIBUTION , Memcached::DISTRIBUTION_CONSISTENT );
foreach($nodes AS $node) {
list($host, $port) = explode(':',$node);
$memcache->addServer($host, $port);
}
$key = "test";
$value = "test";
var_dump(
$memcache->set($key, $value, 0)
);
var_dump($memcache->get($key), $key);
//Memcached::OPT_SERIALIZER
//Memcached::SERIALIZER_PHP
//Memcached::SERIALIZER_IGBINARY
//Memcached::SERIALIZER_JSON
Raw
memcached.key.distribution.test.sh
#!/bin/bash
iface="eth0"
range="192.168.2";
server_count=10;
. /lib/lsb/init-functions
function debug_memcache() {
pid=`ps aux | grep memcache | grep "$1" | awk '{print $2}'`
strace -p $pid -o /tmp/memcached.strace.$2.log &
tcpdump -s 65535 -vv -x -n -q -tttt -i lo dst $1 and port 11211 > /tmp/memcached.tcpdump.$2.log &
}
case $1 in
start)
log_daemon_msg "Starting memcached" "memcached"
for i in $(seq 0 $server_count); do
if ! ip addr show | grep -q "$range.$i/24" > /dev/null; then
ip addr add $range.$i/24 dev eth0
fi;
memcached -l "$range.$i" -uroot -d
debug_memcache "$range.$i" $i
done;
;;
stop)
log_daemon_msg "Stopping memcached" "memcached"
for i in $(seq 0 $server_count); do
if ps aux | grep memcache | grep "$range.$i"; then
kill -9 `ps aux | grep memcache | grep "$range.$i" | awk '{print $2}'`;
fi;
if ps aux | grep tcpdump | grep "$range.$i"; then
kill -9 `ps aux | grep tcpdump | grep "$range.$i" | awk '{print $2}'`;
fi;
if ip addr show | grep -q "$range.$i/24" > /dev/null; then
ip addr del $range.$i/24 dev eth0
fi;
done;
;;
restart)
log_daemon_msg "Restarting memcached" "memcached"
./$0 stop
./$0 start
;;
test)
log_daemon_msg "Testing memcached" "memcached"
server_list="";
for i in $(seq 0 $server_count); do
server_list="$server_list $range.$i:11211";
done;
php memcached.key.distribution.test.php "$server_list"
;;
status)
;;
*)
log_success_msg "Usage: $0 {start|stop|restart|status|test}"
exit 1
;;
esac
echo "";
#echo "stats" | nc 162.31.1.9 11211
#echo "stats settings" | nc 162.31.1.9 11211
#Consistent Hashing
#Consistent Hashing is a model that allows for more stable distribution of keys given addition or removal of servers. In a normal hashing algorithm, changing the number of servers can cause many keys to be remapped to different servers, causing huge sets of cache misses. Consistent Hashing describes methods for mapping keys to a list of servers, where adding or removing servers causes a very minimal shift in where keys map to.
#So in short, with a normal hashing function, adding an eleventh server may cause 40%+ of your keys to suddenly point to different servers than normal.
#However, with a consistent hashing algorithm, adding an eleventh server should cause less than 10% of your keys to be reassigned. In practice this will vary, but it certainly helps.
#TODO: I know there's a better discussion of this that's linkable. help find it? I can never describe it well enough.
Raw
memcached.tcp.txt
2010-06-02 07:00:35.940609 IP6 ::1.45043 > ::1.11211: tcp 0
0x0000: 6000 0000 0028 0640 0000 0000 0000 0000
0x0010: 0000 0000 0000 0001 0000 0000 0000 0000
0x0020: 0000 0000 0000 0001 aff3 2bcb a01b ce68
0x0030: 0000 0000 a002 7ff0 ee24 0000 0204 3ff8
0x0040: 0402 080a 0008 555b 0000 0000 0103 0306
2010-06-02 07:00:35.940642 IP6 ::1.11211 > ::1.45043: tcp 0
0x0000: 6000 0000 0014 0640 0000 0000 0000 0000
0x0010: 0000 0000 0000 0001 0000 0000 0000 0000
0x0020: 0000 0000 0000 0001 2bcb aff3 0000 0000
0x0030: a01b ce69 5014 0000 658b 0000
2010-06-02 07:00:35.940711 IP 127.0.0.1.57157 > 127.0.0.1.11211: tcp 0
0x0000: 4510 003c 489e 4000 4006 f40b 7f00 0001
0x0010: 7f00 0001 df45 2bcb cb4d 1dc2 0000 0000
0x0020: a002 8018 4609 0000 0204 400c 0402 080a
0x0030: 0008 555c 0000 0000 0103 0306
2010-06-02 07:00:35.940732 IP 127.0.0.1.11211 > 127.0.0.1.57157: tcp 0
0x0000: 4500 003c 0000 4000 4006 3cba 7f00 0001
0x0010: 7f00 0001 2bcb df45 cb31 4802 cb4d 1dc3
0x0020: a012 8000 dd77 0000 0204 400c 0402 080a
0x0030: 0008 555c 0008 555c 0103 0306
2010-06-02 07:00:35.940758 IP 127.0.0.1.57157 > 127.0.0.1.11211: tcp 0
0x0000: 4510 0034 489f 4000 4006 f412 7f00 0001
0x0010: 7f00 0001 df45 2bcb cb4d 1dc3 cb31 4803
0x0020: 8010 0201 c49a 0000 0101 080a 0008 555c
0x0030: 0008 555c
2010-06-02 07:00:39.184468 IP 127.0.0.1.57157 > 127.0.0.1.11211: tcp 7
0x0000: 4510 003b 48a0 4000 4006 f40a 7f00 0001
0x0010: 7f00 0001 df45 2bcb cb4d 1dc3 cb31 4803
0x0020: 8018 0201 fe2f 0000 0101 080a 0008 5887
0x0030: 0008 555c 7374 6174 730d 0a
2010-06-02 07:00:39.184508 IP 127.0.0.1.11211 > 127.0.0.1.57157: tcp 0
0x0000: 4500 0034 1d5f 4000 4006 1f63 7f00 0001
0x0010: 7f00 0001 2bcb df45 cb31 4803 cb4d 1dca
0x0020: 8010 0200 be3e 0000 0101 080a 0008 5887
0x0030: 0008 5887
2010-06-02 07:00:39.184751 IP 127.0.0.1.11211 > 127.0.0.1.57157: tcp 788
0x0000: 4500 0348 1d60 4000 4006 1c4e 7f00 0001
0x0010: 7f00 0001 2bcb df45 cb31 4803 cb4d 1dca
0x0020: 8018 0200 013d 0000 0101 080a 0008 5887
0x0030: 0008 5887 5354 4154 2070 6964 2032 3634
0x0040: 340d 0a53 5441 5420 7570 7469 6d65 2032
0x0050: 3433 310d 0a53 5441 5420 7469 6d65 2031
0x0060: 3237 3534 3538 3433 380d 0a53 5441 5420
0x0070: 7665 7273 696f 6e20 312e 342e 350d 0a53
0x0080: 5441 5420 706f 696e 7465 725f 7369 7a65
0x0090: 2033 320d 0a53 5441 5420 7275 7361 6765
0x00a0: 5f75 7365 7220 302e 3030 3030 3030 0d0a
0x00b0: 5354 4154 2072 7573 6167 655f 7379 7374
0x00c0: 656d 2030 2e30 3030 3030 300d 0a53 5441
0x00d0: 5420 6375 7272 5f63 6f6e 6e65 6374 696f
0x00e0: 6e73 2035 0d0a 5354 4154 2074 6f74 616c
0x00f0: 5f63 6f6e 6e65 6374 696f 6e73 2038 0d0a
0x0100: 5354 4154 2063 6f6e 6e65 6374 696f 6e5f
0x0110: 7374 7275 6374 7572 6573 2036 0d0a 5354
0x0120: 4154 2063 6d64 5f67 6574 2031 0d0a 5354
0x0130: 4154 2063 6d64 5f73 6574 2030 0d0a 5354
0x0140: 4154 2063 6d64 5f66 6c75 7368 2030 0d0a
0x0150: 5354 4154 2067 6574 5f68 6974 7320 300d
0x0160: 0a53 5441 5420 6765 745f 6d69 7373 6573
0x0170: 2031 0d0a 5354 4154 2064 656c 6574 655f
0x0180: 6d69 7373 6573 2030 0d0a 5354 4154 2064
0x0190: 656c 6574 655f 6869 7473 2030 0d0a 5354
0x01a0: 4154 2069 6e63 725f 6d69 7373 6573 2030
0x01b0: 0d0a 5354 4154 2069 6e63 725f 6869 7473
0x01c0: 2030 0d0a 5354 4154 2064 6563 725f 6d69
0x01d0: 7373 6573 2030 0d0a 5354 4154 2064 6563
0x01e0: 725f 6869 7473 2030 0d0a 5354 4154 2063
0x01f0: 6173 5f6d 6973 7365 7320 300d 0a53 5441
0x0200: 5420 6361 735f 6869 7473 2030 0d0a 5354
0x0210: 4154 2063 6173 5f62 6164 7661 6c20 300d
0x0220: 0a53 5441 5420 6175 7468 5f63 6d64 7320
0x0230: 300d 0a53 5441 5420 6175 7468 5f65 7272
0x0240: 6f72 7320 300d 0a53 5441 5420 6279 7465
0x0250: 735f 7265 6164 2036 330d 0a53 5441 5420
0x0260: 6279 7465 735f 7772 6974 7465 6e20 3136
0x0270: 3133 0d0a 5354 4154 206c 696d 6974 5f6d
0x0280: 6178 6279 7465 7320 3637 3130 3838 3634
0x0290: 0d0a 5354 4154 2061 6363 6570 7469 6e67
0x02a0: 5f63 6f6e 6e73 2031 0d0a 5354 4154 206c
0x02b0: 6973 7465 6e5f 6469 7361 626c 6564 5f6e
0x02c0: 756d 2030 0d0a 5354 4154 2074 6872 6561
0x02d0: 6473 2034 0d0a 5354 4154 2063 6f6e 6e5f
0x02e0: 7969 656c 6473 2030 0d0a 5354 4154 2062
0x02f0: 7974 6573 2030 0d0a 5354 4154 2063 7572
0x0300: 725f 6974 656d 7320 300d 0a53 5441 5420
0x0310: 746f 7461 6c5f 6974 656d 7320 300d 0a53
0x0320: 5441 5420 6576 6963 7469 6f6e 7320 300d
0x0330: 0a53 5441 5420 7265 636c 6169 6d65 6420
0x0340: 300d 0a45 4e44 0d0a
2010-06-02 07:00:39.184765 IP 127.0.0.1.57157 > 127.0.0.1.11211: tcp 0
0x0000: 4510 0034 48a1 4000 4006 f410 7f00 0001
0x0010: 7f00 0001 df45 2bcb cb4d 1dca cb31 4b17
0x0020: 8010 0219 bb11 0000 0101 080a 0008 5887
0x0030: 0008 5887
2010-06-02 07:00:43.096977 IP 127.0.0.1.57157 > 127.0.0.1.11211: tcp 0
0x0000: 4510 0034 48a2 4000 4006 f40f 7f00 0001
0x0010: 7f00 0001 df45 2bcb cb4d 1dca cb31 4b17
0x0020: 8011 0219 b73e 0000 0101 080a 0008 5c59
0x0030: 0008 5887
2010-06-02 07:00:43.097280 IP 127.0.0.1.11211 > 127.0.0.1.57157: tcp 0
0x0000: 4500 0034 1d61 4000 4006 1f61 7f00 0001
0x0010: 7f00 0001 2bcb df45 cb31 4b17 cb4d 1dcb
0x0020: 8011 0200 b384 0000 0101 080a 0008 5c59
0x0030: 0008 5c59
2010-06-02 07:00:43.097303 IP 127.0.0.1.57157 > 127.0.0.1.11211: tcp 0
0x0000: 4510 0034 48a3 4000 4006 f40e 7f00 0001
0x0010: 7f00 0001 df45 2bcb cb4d 1dcb cb31 4b18
0x0020: 8010 0219 b36b 0000 0101 080a 0008 5c59
0x0030: 0008 5c59
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