Redis的Multi的内幕真相

今天遇到個Redis奇慢的問題，斷點分析發現跟multi有關。

由于本人太忙不想去閱讀Redis Server的源代碼（其實是懶），就通過TCPDump來分析吧。

步驟：

1. 先在Redis Server上啟動TCPDump: tcpdump -i eno16777736 port 6379 -X

2. 測試Multi:

<?php

$redis = new redis();
$result = $redis->connect('localhost', 6379);
//預設是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資料：

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. 　　（加入隊列）
	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..          （執行3次請求後批量傳回3個結果）
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. 測試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資料分析:

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，批量發送、執行）
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，傳回結果）      

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)!)      

總結一下：

1. Multi:

　　1.1. 每發送一條指令，都需要單獨發給伺服器，伺服器再單獨傳回“該條指令已加入隊列”這個消息。這是比Pipeline慢的原因之一。

　　1.2. Multi執行的時候會先暫停其他指令的執行，類似于加了個鎖，直到整個Multi結束完成再繼續其他用戶端的請求。這是Multi能保證一緻性的原因，也是比Pipeline慢的原因之二。（需要讀Redis Server的代碼，從TCPDump上看不出）

2. Pipeline:

　　2.1. 将所有指令打包一次性發送。發送成功後，服務端不用傳回類似“指令已收到”這樣的消息，而是一次性批量執行所有指令，成功後再一次性傳回所有處理結果。

　　2.2. 服務端處理指令的時候，不需要加鎖，而是與其他用戶端的指令混合在一起處理，是以無法保證一緻性。

适用場景：

1. 如果要順序執行一組指令（既網上所謂的“Redis事務”），Multi很合适。

2. 如果要往Redis裡批量插入Log, 或者使用Redis List做為隊列并插入很多消息的話，Pipleline是挺合适的。 

3. 網絡不好，又順序性不強的資料，适合Pipleline 

性能：

without pipelining 1.185238 seconds
with pipelining 0.250783 seconds （有時能快一個數量級）           

參考：https://redis.io/topics/pipelining

謀膽并重