今天遇到个Redis奇慢的问题，断点分析发现跟multi有关。
由于本人太忙不想去阅读Redis Server的源代码（其实是懒），就通过TCPDump来分析吧。
步骤：
1. 先在Redis Server上启动TCPDump: tcpdump -i eno16777736 port 6379 -X
2. 测试Multi:
<?php
$redis = new redis();
$result = $redis->connect('localhost', 6379);
//默认是Redis::MULTI
$multi = $redis->multi();
for($i=0;$i<100;$i++)
$multi->set('testkey' . (string)$i, 'helloworld' . (string)$i);
$replies = $multi->exec();
var_dump($replies);
?>
TCPDump抓包：
sudo tcpdump -i lo0 port 6379 -XX -vvv
TCPDump数据：
19:09:22.437455 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 64, bad cksum 0 (->3cb6)!)
localhost.60828 > localhost.6379: Flags [S], cksum 0xfe34 (incorrect -> 0x48c3), seq 3085749856, win 65535, options [mss 16344,nop,wscale 5,nop,nop,TS val 472321303 ecr 0,sackOK,eol], length 0
0x0000: 0200 0000 4500 0040 0000 4000 4006 0000 ....E..@..@.@...
0x0010: 7f00 0001 7f00 0001 ed9c 18eb b7ec ce60 ...............`
0x0020: 0000 0000 b002 ffff fe34 0000 0204 3fd8 .........4....?.
0x0030: 0103 0305 0101 080a 1c27 0d17 0000 0000 .........'......
0x0040: 0402 0000 ....
19:09:22.437505 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 64, bad cksum 0 (->3cb6)!)
localhost.6379 > localhost.60828: Flags [S.], cksum 0xfe34 (incorrect -> 0x8ab4), seq 934042899, ack 3085749857, win 65535, options [mss 16344,nop,wscale 5,nop,nop,TS val 472321303 ecr 472321303,sackOK,eol], length 0
0x0000: 0200 0000 4500 0040 0000 4000 4006 0000 ....E..@..@.@...
0x0010: 7f00 0001 7f00 0001 18eb ed9c 37ac 5d13 ............7.].
0x0020: b7ec ce61 b012 ffff fe34 0000 0204 3fd8 ...a.....4....?.
0x0030: 0103 0305 0101 080a 1c27 0d17 1c27 0d17 .........'...'..
0x0040: 0402 0000 ....
19:09:22.437515 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.60828 > localhost.6379: Flags [.], cksum 0xfe28 (incorrect -> 0xd2d0), seq 1, ack 1, win 12759, options [nop,nop,TS val 472321303 ecr 472321303], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 ed9c 18eb b7ec ce61 ...............a
0x0020: 37ac 5d14 8010 31d7 fe28 0000 0101 080a 7.]...1..(......
0x0030: 1c27 0d17 1c27 0d17 .'...'..
19:09:22.437525 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.6379 > localhost.60828: Flags [.], cksum 0xfe28 (incorrect -> 0xd2d0), seq 1, ack 1, win 12759, options [nop,nop,TS val 472321303 ecr 472321303], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 18eb ed9c 37ac 5d14 ............7.].
0x0020: b7ec ce61 8010 31d7 fe28 0000 0101 080a ...a..1..(......
0x0030: 1c27 0d17 1c27 0d17 .'...'..
19:09:22.437866 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 67, bad cksum 0 (->3cb3)!)
localhost.60828 > localhost.6379: Flags [P.], cksum 0xfe37 (incorrect -> 0x7d88), seq 1:16, ack 1, win 12759, options [nop,nop,TS val 472321303 ecr 472321303], length 15: RESP "MULTI"
0x0000: 0200 0000 4500 0043 0000 4000 4006 0000 ....E..C..@.@...
0x0010: 7f00 0001 7f00 0001 ed9c 18eb b7ec ce61 ...............a
0x0020: 37ac 5d14 8018 31d7 fe37 0000 0101 080a 7.]...1..7......
0x0030: 1c27 0d17 1c27 0d17 2a31 0d0a 2435 0d0a .'...'..*1..$5..
0x0040: 4d55 4c54 490d 0a MULTI..
19:09:22.437885 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.6379 > localhost.60828: Flags [.], cksum 0xfe28 (incorrect -> 0xd2c2), seq 1, ack 16, win 12758, options [nop,nop,TS val 472321303 ecr 472321303], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 18eb ed9c 37ac 5d14 ............7.].
0x0020: b7ec ce70 8010 31d6 fe28 0000 0101 080a ...p..1..(......
0x0030: 1c27 0d17 1c27 0d17 .'...'..
19:09:22.437979 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 57, bad cksum 0 (->3cbd)!)
localhost.6379 > localhost.60828: Flags [P.], cksum 0xfe2d (incorrect -> 0x5259), seq 1:6, ack 16, win 12758, options [nop,nop,TS val 472321303 ecr 472321303], length 5: RESP "OK"
0x0000: 0200 0000 4500 0039 0000 4000 4006 0000 ....E..9..@.@...
0x0010: 7f00 0001 7f00 0001 18eb ed9c 37ac 5d14 ............7.].
0x0020: b7ec ce70 8018 31d6 fe2d 0000 0101 080a ...p..1..-......
0x0030: 1c27 0d17 1c27 0d17 2b4f 4b0d 0a .'...'..+OK..
19:09:22.437993 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.60828 > localhost.6379: Flags [.], cksum 0xfe28 (incorrect -> 0xd2bc), seq 16, ack 6, win 12759, options [nop,nop,TS val 472321303 ecr 472321303], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 ed9c 18eb b7ec ce70 ...............p
0x0020: 37ac 5d19 8010 31d7 fe28 0000 0101 080a 7.]...1..(......
0x0030: 1c27 0d17 1c27 0d17 .'...'..
19:09:22.438224 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 97, bad cksum 0 (->3c95)!)
localhost.60828 > localhost.6379: Flags [P.], cksum 0xfe55 (incorrect -> 0x6423), seq 16:61, ack 6, win 12759, options [nop,nop,TS val 472321303 ecr 472321303], length 45: RESP "SET" "testkey0" "helloworld0"
0x0000: 0200 0000 4500 0061 0000 4000 4006 0000 ....E..a..@.@...
0x0010: 7f00 0001 7f00 0001 ed9c 18eb b7ec ce70 ...............p
0x0020: 37ac 5d19 8018 31d7 fe55 0000 0101 080a 7.]...1..U......
0x0030: 1c27 0d17 1c27 0d17 2a33 0d0a 2433 0d0a .'...'..*3..$3..
0x0040: 5345 540d 0a24 380d 0a74 6573 746b 6579 SET..$8..testkey
0x0050: 300d 0a24 3131 0d0a 6865 6c6c 6f77 6f72 0..$11..hellowor
0x0060: 6c64 300d 0a ld0..
19:09:22.438245 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.6379 > localhost.60828: Flags [.], cksum 0xfe28 (incorrect -> 0xd291), seq 6, ack 61, win 12757, options [nop,nop,TS val 472321303 ecr 472321303], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 18eb ed9c 37ac 5d19 ............7.].
0x0020: b7ec ce9d 8010 31d5 fe28 0000 0101 080a ......1..(......
0x0030: 1c27 0d17 1c27 0d17 .'...'..
19:09:22.438291 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 61, bad cksum 0 (->3cb9)!)
localhost.6379 > localhost.60828: Flags [P.], cksum 0xfe31 (incorrect -> 0xae97), seq 6:15, ack 61, win 12757, options [nop,nop,TS val 472321303 ecr 472321303], length 9: RESP "QUEUED"
0x0000: 0200 0000 4500 003d 0000 4000 4006 0000 ....E..=..@.@...
0x0010: 7f00 0001 7f00 0001 18eb ed9c 37ac 5d19 ............7.].
0x0020: b7ec ce9d 8018 31d5 fe31 0000 0101 080a ......1..1......
0x0030: 1c27 0d17 1c27 0d17 2b51 5545 5545 440d .'...'..+QUEUED.
0x0040: 0a .
19:09:22.438307 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.60828 > localhost.6379: Flags [.], cksum 0xfe28 (incorrect -> 0xd287), seq 61, ack 15, win 12758, options [nop,nop,TS val 472321303 ecr 472321303], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 ed9c 18eb b7ec ce9d ................
0x0020: 37ac 5d22 8010 31d6 fe28 0000 0101 080a 7.]"..1..(......
0x0030: 1c27 0d17 1c27 0d17 .'...'..
19:09:22.438362 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 97, bad cksum 0 (->3c95)!)
localhost.60828 > localhost.6379: Flags [P.], cksum 0xfe55 (incorrect -> 0x61ee), seq 61:106, ack 15, win 12758, options [nop,nop,TS val 472321303 ecr 472321303], length 45: RESP "SET" "testkey1" "helloworld1"
0x0000: 0200 0000 4500 0061 0000 4000 4006 0000 ....E..a..@.@...
0x0010: 7f00 0001 7f00 0001 ed9c 18eb b7ec ce9d ................
0x0020: 37ac 5d22 8018 31d6 fe55 0000 0101 080a 7.]"..1..U......
0x0030: 1c27 0d17 1c27 0d17 2a33 0d0a 2433 0d0a .'...'..*3..$3..
0x0040: 5345 540d 0a24 380d 0a74 6573 746b 6579 SET..$8..testkey
0x0050: 310d 0a24 3131 0d0a 6865 6c6c 6f77 6f72 1..$11..hellowor
0x0060: 6c64 310d 0a ld1..
19:09:22.438378 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.6379 > localhost.60828: Flags [.], cksum 0xfe28 (incorrect -> 0xd25c), seq 15, ack 106, win 12756, options [nop,nop,TS val 472321303 ecr 472321303], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 18eb ed9c 37ac 5d22 ............7.]"
0x0020: b7ec ceca 8010 31d4 fe28 0000 0101 080a ......1..(......
0x0030: 1c27 0d17 1c27 0d17 .'...'..
19:09:22.438396 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 61, bad cksum 0 (->3cb9)!)
localhost.6379 > localhost.60828: Flags [P.], cksum 0xfe31 (incorrect -> 0xae62), seq 15:24, ack 106, win 12756, options [nop,nop,TS val 472321303 ecr 472321303], length 9: RESP "QUEUED"
0x0000: 0200 0000 4500 003d 0000 4000 4006 0000 ....E..=..@.@...
0x0010: 7f00 0001 7f00 0001 18eb ed9c 37ac 5d22 ............7.]"
0x0020: b7ec ceca 8018 31d4 fe31 0000 0101 080a ......1..1......
0x0030: 1c27 0d17 1c27 0d17 2b51 5545 5545 440d .'...'..+QUEUED.
0x0040: 0a .
19:09:22.438407 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.60828 > localhost.6379: Flags [.], cksum 0xfe28 (incorrect -> 0xd250), seq 106, ack 24, win 12758, options [nop,nop,TS val 472321304 ecr 472321303], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 ed9c 18eb b7ec ceca ................
0x0020: 37ac 5d2b 8010 31d6 fe28 0000 0101 080a 7.]+..1..(......
0x0030: 1c27 0d18 1c27 0d17 .'...'..
19:09:22.438444 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 97, bad cksum 0 (->3c95)!)
localhost.60828 > localhost.6379: Flags [P.], cksum 0xfe55 (incorrect -> 0x5fb7), seq 106:151, ack 24, win 12758, options [nop,nop,TS val 472321304 ecr 472321303], length 45: RESP "SET" "testkey2" "helloworld2"
0x0000: 0200 0000 4500 0061 0000 4000 4006 0000 ....E..a..@.@...
0x0010: 7f00 0001 7f00 0001 ed9c 18eb b7ec ceca ................
0x0020: 37ac 5d2b 8018 31d6 fe55 0000 0101 080a 7.]+..1..U......
0x0030: 1c27 0d18 1c27 0d17 2a33 0d0a 2433 0d0a .'...'..*3..$3..
0x0040: 5345 540d 0a24 380d 0a74 6573 746b 6579 SET..$8..testkey
0x0050: 320d 0a24 3131 0d0a 6865 6c6c 6f77 6f72 2..$11..hellowor
0x0060: 6c64 320d 0a ld2..
19:09:22.438457 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.6379 > localhost.60828: Flags [.], cksum 0xfe28 (incorrect -> 0xd226), seq 24, ack 151, win 12754, options [nop,nop,TS val 472321304 ecr 472321304], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 18eb ed9c 37ac 5d2b ............7.]+
0x0020: b7ec cef7 8010 31d2 fe28 0000 0101 080a ......1..(......
0x0030: 1c27 0d18 1c27 0d18 .'...'..
19:09:22.438484 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 61, bad cksum 0 (->3cb9)!)
localhost.6379 > localhost.60828: Flags [P.], cksum 0xfe31 (incorrect -> 0xae2c), seq 24:33, ack 151, win 12754, options [nop,nop,TS val 472321304 ecr 472321304], length 9: RESP "QUEUED"
0x0000: 0200 0000 4500 003d 0000 4000 4006 0000 ....E..=..@.@...
0x0010: 7f00 0001 7f00 0001 18eb ed9c 37ac 5d2b ............7.]+
0x0020: b7ec cef7 8018 31d2 fe31 0000 0101 080a ......1..1......
0x0030: 1c27 0d18 1c27 0d18 2b51 5545 5545 440d .'...'..+QUEUED. （加入队列）
0x0040: 0a .
19:09:22.438493 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.60828 > localhost.6379: Flags [.], cksum 0xfe28 (incorrect -> 0xd219), seq 151, ack 33, win 12758, options [nop,nop,TS val 472321304 ecr 472321304], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 ed9c 18eb b7ec cef7 ................
0x0020: 37ac 5d34 8010 31d6 fe28 0000 0101 080a 7.]4..1..(......
0x0030: 1c27 0d18 1c27 0d18 .'...'..
19:09:22.438534 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 66, bad cksum 0 (->3cb4)!)
localhost.60828 > localhost.6379: Flags [P.], cksum 0xfe36 (incorrect -> 0xd1e4), seq 151:165, ack 33, win 12758, options [nop,nop,TS val 472321304 ecr 472321304], length 14: RESP "EXEC"
0x0000: 0200 0000 4500 0042 0000 4000 4006 0000 ....E..B..@.@...
0x0010: 7f00 0001 7f00 0001 ed9c 18eb b7ec cef7 ................
0x0020: 37ac 5d34 8018 31d6 fe36 0000 0101 080a 7.]4..1..6......
0x0030: 1c27 0d18 1c27 0d18 2a31 0d0a 2434 0d0a .'...'..*1..$4..
0x0040: 4558 4543 0d0a EXEC..
19:09:22.438546 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.6379 > localhost.60828: Flags [.], cksum 0xfe28 (incorrect -> 0xd20f), seq 33, ack 165, win 12754, options [nop,nop,TS val 472321304 ecr 472321304], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 18eb ed9c 37ac 5d34 ............7.]4
0x0020: b7ec cf05 8010 31d2 fe28 0000 0101 080a ......1..(......
0x0030: 1c27 0d18 1c27 0d18 .'...'..
19:09:22.438582 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 71, bad cksum 0 (->3caf)!)
localhost.6379 > localhost.60828: Flags [P.], cksum 0xfe3b (incorrect -> 0x3d7e), seq 33:52, ack 165, win 12754, options [nop,nop,TS val 472321304 ecr 472321304], length 19: RESP "OK" "OK" "OK"
0x0000: 0200 0000 4500 0047 0000 4000 4006 0000 ....E..G..@.@...
0x0010: 7f00 0001 7f00 0001 18eb ed9c 37ac 5d34 ............7.]4
0x0020: b7ec cf05 8018 31d2 fe3b 0000 0101 080a ......1..;......
0x0030: 1c27 0d18 1c27 0d18 2a33 0d0a 2b4f 4b0d .'...'..*3..+OK.
0x0040: 0a2b 4f4b 0d0a 2b4f 4b0d 0a .+OK..+OK.. （执行3次请求后批量返回3个结果）
19:09:22.438593 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.60828 > localhost.6379: Flags [.], cksum 0xfe28 (incorrect -> 0xd1f9), seq 165, ack 52, win 12757, options [nop,nop,TS val 472321304 ecr 472321304], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 ed9c 18eb b7ec cf05 ................
0x0020: 37ac 5d47 8010 31d5 fe28 0000 0101 080a 7.]G..1..(......
0x0030: 1c27 0d18 1c27 0d18 .'...'..
3. 测试Multi PIPELINE:
<?php
$redis = new redis();
$result = $redis->connect('localhost', 6379);
$multi = $redis->multi(Redis::PIPELINE);
for($i=0;$i<100;$i++)
$multi->set('testkey' . (string)$i, 'helloworld' . (string)$i);
$replies = $multi->exec();
var_dump($replies);
TCPDUMP数据分析:
19:21:38.905913 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 64, bad cksum 0 (->3cb6)!)
localhost.63949 > localhost.6379: Flags [S], cksum 0xfe34 (incorrect -> 0x21b4), seq 3990454584, win 65535, options [mss 16344,nop,wscale 5,nop,nop,TS val 473055013 ecr 0,sackOK,eol], length 0
0x0000: 0200 0000 4500 0040 0000 4000 4006 0000 ....E..@..@.@...
0x0010: 7f00 0001 7f00 0001 f9cd 18eb edd9 8138 ...............8
0x0020: 0000 0000 b002 ffff fe34 0000 0204 3fd8 .........4....?.
0x0030: 0103 0305 0101 080a 1c32 3f25 0000 0000 .........2?%....
0x0040: 0402 0000 ....
19:21:38.905963 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 64, bad cksum 0 (->3cb6)!)
localhost.6379 > localhost.63949: Flags [S.], cksum 0xfe34 (incorrect -> 0x077e), seq 3128427605, ack 3990454585, win 65535, options [mss 16344,nop,wscale 5,nop,nop,TS val 473055013 ecr 473055013,sackOK,eol], length 0
0x0000: 0200 0000 4500 0040 0000 4000 4006 0000 ....E..@..@.@...
0x0010: 7f00 0001 7f00 0001 18eb f9cd ba78 0455 .............x.U
0x0020: edd9 8139 b012 ffff fe34 0000 0204 3fd8 ...9.....4....?.
0x0030: 0103 0305 0101 080a 1c32 3f25 1c32 3f25 .........2?%.2?%
0x0040: 0402 0000 ....
19:21:38.905975 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.63949 > localhost.6379: Flags [.], cksum 0xfe28 (incorrect -> 0x4f9a), seq 1, ack 1, win 12759, options [nop,nop,TS val 473055013 ecr 473055013], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 f9cd 18eb edd9 8139 ...............9
0x0020: ba78 0456 8010 31d7 fe28 0000 0101 080a .x.V..1..(......
0x0030: 1c32 3f25 1c32 3f25 .2?%.2?%
19:21:38.905985 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.6379 > localhost.63949: Flags [.], cksum 0xfe28 (incorrect -> 0x4f9a), seq 1, ack 1, win 12759, options [nop,nop,TS val 473055013 ecr 473055013], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 18eb f9cd ba78 0456 .............x.V
0x0020: edd9 8139 8010 31d7 fe28 0000 0101 080a ...9..1..(......
0x0030: 1c32 3f25 1c32 3f25 .2?%.2?%
19:21:38.914905 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 187, bad cksum 0 (->3c3b)!)
localhost.63949 > localhost.6379: Flags [P.], cksum 0xfeaf (incorrect -> 0x09c9), seq 1:136, ack 1, win 12759, options [nop,nop,TS val 473055022 ecr 473055013], length 135: RESP "SET" "testkey0" "helloworld0" "SET" "testkey1" "helloworld1" "SET" "testkey2" "helloworld2"
0x0000: 0200 0000 4500 00bb 0000 4000 4006 0000 ....E.....@.@...
0x0010: 7f00 0001 7f00 0001 f9cd 18eb edd9 8139 ...............9
0x0020: ba78 0456 8018 31d7 feaf 0000 0101 080a .x.V..1.........
0x0030: 1c32 3f2e 1c32 3f25 2a33 0d0a 2433 0d0a .2?..2?%*3..$3..
0x0040: 5345 540d 0a24 380d 0a74 6573 746b 6579 SET..$8..testkey
0x0050: 300d 0a24 3131 0d0a 6865 6c6c 6f77 6f72 0..$11..hellowor
0x0060: 6c64 300d 0a2a 330d 0a24 330d 0a53 4554 ld0..*3..$3..SET
0x0070: 0d0a 2438 0d0a 7465 7374 6b65 7931 0d0a ..$8..testkey1..
0x0080: 2431 310d 0a68 656c 6c6f 776f 726c 6431 $11..helloworld1
0x0090: 0d0a 2a33 0d0a 2433 0d0a 5345 540d 0a24 ..*3..$3..SET..$
0x00a0: 380d 0a74 6573 746b 6579 320d 0a24 3131 8..testkey2..$11
0x00b0: 0d0a 6865 6c6c 6f77 6f72 6c64 320d 0a ..helloworld2.. （一次性，批量发送、执行）
19:21:38.914935 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
localhost.6379 > localhost.63949: Flags [.], cksum 0xfe28 (incorrect -> 0x4f05), seq 1, ack 136, win 12755, options [nop,nop,TS val 473055022 ecr 473055022], length 0
0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@...
0x0010: 7f00 0001 7f00 0001 18eb f9cd ba78 0456 .............x.V
0x0020: edd9 81c0 8010 31d3 fe28 0000 0101 080a ......1..(......
0x0030: 1c32 3f2e 1c32 3f2e .2?..2?.
19:21:38.915037 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 67, bad cksum 0 (->3cb3)!)
localhost.6379 > localhost.63949: Flags [P.], cksum 0xfe37 (incorrect -> 0xf1b4), seq 1:16, ack 136, win 12755, options [nop,nop,TS val 473055022 ecr 473055022], length 15: RESP "OK" "OK" "OK"
0x0000: 0200 0000 4500 0043 0000 4000 4006 0000 ....E..C..@.@...
0x0010: 7f00 0001 7f00 0001 18eb f9cd ba78 0456 .............x.V
0x0020: edd9 81c0 8018 31d3 fe37 0000 0101 080a ......1..7......
0x0030: 1c32 3f2e 1c32 3f2e 2b4f 4b0d 0a2b 4f4b .2?..2?.+OK..+OK
0x0040: 0d0a 2b4f 4b0d 0a ..+OK.. （一次性，返回结果）
19:21:38.915060 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!) localhost.63949 > localhost.6379: Flags [.], cksum 0xfe28 (incorrect -> 0x4ef3), seq 136, ack 16, win 12758, options [nop,nop,TS val 473055022 ecr 473055022], length 0 0x0000: 0200 0000 4500 0034 0000 4000 4006 0000 ....E..4..@.@... 0x0010: 7f00 0001 7f00 0001 f9cd 18eb edd9 81c0 ................ 0x0020: ba78 0465 8010 31d6 fe28 0000 0101 080a .x.e..1..(...... 0x0030: 1c32 3f2e 1c32 3f2e .2?..2?. 19:21:38.916018 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->3cc2)!)
总结一下：
1. Multi:
1.1. 每发送一条指令，都需要单独发给服务器，服务器再单独返回“该条指令已加入队列”这个消息。这是比Pipeline慢的原因之一。
1.2. Multi执行的时候会先暂停其他命令的执行，类似于加了个锁，直到整个Multi结束完成再继续其他客户端的请求。这是Multi能保证一致性的原因，也是比Pipeline慢的原因之二。（需要读Redis Server的代码，从TCPDump上看不出）
2. Pipeline:
2.1. 将所有命令打包一次性发送。发送成功后，服务端不用返回类似“命令已收到”这样的消息，而是一次性批量执行所有命令，成功后再一次性返回所有处理结果。
2.2. 服务端处理命令的时候，不需要加锁，而是与其他客户端的命令混合在一起处理，所以无法保证一致性。
适用场景：
1. 如果要顺序执行一组命令（既网上所谓的“Redis事务”），Multi很合适。
2. 如果要往Redis里批量插入Log, 或者使用Redis List做为队列并插入很多消息的话，Pipleline是挺合适的。
3. 网络不好，又顺序性不强的数据，适合Pipleline
性能：
without pipelining 1.185238 seconds
with pipelining 0.250783 seconds （有时能快一个数量级）
参考：https://redis.io/topics/pipelining
作者：sunsky303