1. Gazelle
Plack Handler for performance freaks
Yokohama.pm #12
Masahiro Nagano (kazeburo)
https://www.!ickr.com/photos/ckindel/424610604/

2. Me
• 長野雅広 (Masahiro Nagano)
• @kazeburo
• CPAN: KAZEBURO / github: kazeburo
• 横浜市西区在住
• ISUCON 2013,2014 優勝

3. Gazelle

4. Gazelle #とは
• Plack Handler / PSGI Server
• HTTP/1.0 Web Server
• Preforking Architecture
• Suitable for running application servers
behind a reverse proxy
• Starlet compatible / hot deploy
• Fast Fast Fast

5. “Hello World”
130,000
97,500
req/sec nginx starman Starlet Gazelle
65,000
32,500
0
106,028
62,069
33,300
127,462
3x Faster!!
than starman

6. “counter.psgi”
110,000
82,500
55,000
27,500
0
42,285
106,028
28,292
62,069
20,100
33,300
hello world counter.psgi
req/sec
starman Starlet Gazelle

7. ISUCON4 Quali!er
45,000
33,750
Score 予選通過ラインstarman Starlet Gazelle
22,500
11,250
39,776 42,813 44,764 37,808
「ISUCON4 予選でアプリケーションを変更せずに予選通過ラインを突破するの術」
に若干変更を加えたバージョン

8. Gazelle はなぜ速い
• Only Support HTTP/1.0 and does not
support KeepAlive. It make code very simple
• Mostly written in XS
• Ultra fast HTTP processing using
picohttpparser
• Use accept4(2)
• Use writev(2) for output responses

9. Simple HTTP/1.0 GET
accept4(2)
read(2)
parse_header
poll(2)
complete?
OK
execute app
writev(2)
poll(2)
written?
close(2)
No
OK No

10. Mostly written in XS
accept4(2)
read(2)
parse_header
poll(2)
complete?
OK
execute app
writev(2)
poll(2)
written?
close(2)
No
OK No
XS
XS

11. Perl code using XS
while (1) {
if ( my ($fd, $buf, $env) = accept_psgi(
fileno($listen_sock), $timeout, $listen_sock_is_tcp,
$host || 0, $port || 0
) ) {
my $guard = guard { close_client($fd) };
$res = Plack::Util::run_app $app, $env;
my $status_code = $res->[0];
my $headers = $res->[1];
my $body = $res->[2];
write_psgi_response($fd, $timeout, $status_code, $headers, $body);
}

12. Perl code using XS
while (1) {
if ( my ($fd, $buf, $env) = accept_psgi(
fileno($listen_sock), $timeout, $listen_sock_is_tcp,
$host || 0, $port || 0
) ) {
my $guard = guard { close_client($fd) };
$res = Plack::Util::run_app $app, $env;
my $status_code = $res->[0];
my $headers = $res->[1];
my $body = $res->[2];
write_psgi_response($fd, $timeout, $status_code, $headers, $body);
}

13. picohttpparser
• created by kazuho-san
• used in H2O and HTTP::Parser::XS

14. 必読
http://blog.kazuhooku.com/2014/11/the-internals-h2o-or-how-to-write-fast.html

15. accept4(2)
• Required Linux >= 2.6.28
• Set FD_CLOEXEC and O_NONBLOCK in
one system call

16. accept4(2)
int
_accept(int fileno, struct sockaddr *addr, unsigned int addrlen) {
int fd;
#ifdef SOCK_NONBLOCK
fd = accept4(fileno, addr, &addrlen, SOCK_CLOEXEC|SOCK_NONBLOCK);
#else
fd = accept(fileno, addr, &addrlen);
fcntl(fd, F_SETFD, FD_CLOEXEC);
fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);
#endif
return fd;
}

17. accept4(2)
13:51:26.755628 accept(4, {sa_family=AF_INET, sin_port=htons(42828),
sin_addr=inet_addr("127.0.0.1")}, [16]) = 5
13:51:27.324951 fcntl(5, F_SETFD, FD_CLOEXEC) = 0
13:51:27.325014 fcntl(5, F_GETFL) = 0x2 (flags O_RDWR)
13:51:27.325067 fcntl(5, F_SETFL, O_RDWR|O_NONBLOCK) = 0
13:51:27.325117 read(5, "GET / HTTP/1.1rnUser-Agent:"..., 16384) = 155
13:51:27.325200 setsockopt(5, SOL_TCP, TCP_NODELAY, [1], 4) = 0
13:52:17.946622 accept4(4, {sa_family=AF_INET, sin_port=htons(42835),
sin_addr=inet_addr("127.0.0.1")}, [16], SOCK_CLOEXEC|SOCK_NONBLOCK) = 5
13:52:18.505428 read(5, "GET / HTTP/1.1rnUser-Agent:”..., 16384) = 155
13:52:18.505519 setsockopt(5, SOL_TCP, TCP_NODELAY, [1], 4) = 0

18. writev
• write multiple buffer to a fd in one
system call
• reduce memory copy or system calls

19. ex. memory copy
#perl
my $header = ["Server"=>"gazelle","Content-Type"=>"text/plain",...];
#xs
char buf[512];
while ( i < av_len(headers) + 1 ) {
key = SvPV_nolen(*av_fetch(headers,i++,0));
strcat(buf, key);
strcat(buf, ": ");
val = SvPV_nolen(*av_fetch(headers,i++,0));
strcat(buf, val);
strcat(buf, "rn");
}
write(fd, buf, sizeof(buf)-1);
Too many
memory copy
cause system
overhead

20. ex. write write write
#perl
my $header = ["Server"=>"gazelle","Content-Type"=>"text/plain"];
#xs
while ( i < av_len(headers) + 1 ) {
key = SvPV(*av_fetch(headers,i++,0),&len);
write(fd, key, len);
write(fd, ": ", sizeof(“: ”) - 1);
val = SvPV(*av_fetch(headers,i++,0),&len);
write(fd, val, len);
write(fd, "rn", sizeof(“rn”) - 1);
}
Too many
write(2)
increase latency
of network

21. writev(2)
#perl
my $header = ["Server"=>"gazelle","Content-Type"=>"text/plain"];
#xs
struct iovec v[av_len(headers)+1)*2 + 10];
iovcnt = 0;
while ( i < av_len(headers) + 1 ) {
key = SvPV(*av_fetch(headers,i++,0),&len);
iovcnt++;
v[iovcnt].iov_base = key;
v[iovcnt].iov_len = len;
iovcnt++;
v[iovcnt].iov_base = “: ”;
no memory copy
v[iovcnt].iov_len = sizeof(“: ”) - 1;
one system call
...
}
writev(fd, v, iovcnt);

22. writev(2)
plackup -s Gazelle -e 'sub{[200,["Content-Type"=>"text/plain"],
["xxx","xxx","yyy","yyy","zzzz","n"]]}'
writev(5, [{"HTTP/1.0 200 OKrnConnection: closernServer: gazeller
n", 53}, {"Content-Type", 12}, {": ", 2}, {"text/plain", 10}, {"rn",
2}, {"Date: Fri, 28 Nov 2014 04:38:08 GMTrnrn", 39}, {"xxx", 3},
{"xxx", 3}, {"yyy", 3}, {"yyy", 3}, {"zzzz", 4}, {"n", 1}], 12) = 135

23. 高速なサーバを書くには
• write XS, minimize Perl code
• reduce system calls
• Zero Copy

24. 高速なAppサーバって必要なの？
• ISUCON :)
• Social Games, AdTech, SNS
• High optimized applications
• few msec ~ few tens of msec
• Several hundreds of request/sec/host
• 1PVあたりの利益が小さいサービス

25. Gazelleの実績
• livedoor Blog
• 2500万req/day/host
• Starletからの移行でCPU使用率
1%~3%さがった

26. ぜひお使い下さい
https://www.!ickr.com/photos/superformosa/9057428400/