First step of Performance Tuning

by risou
at YAPC::Kansai 2017 Osaka

▸ risou
▸ ID "risouf"
▸
▸ 🤔
▸
▸ 🙏

▸ 10
▸ 10 ……
▸
▸ 10 5

▸
A
3h
B
1h
C
0.5h
D
1h
E
2h
F
1h
G
4h
H
2h

▸
my @primes = ();
for my $num (2 .. 100_000) {
if ($num == 2) {
push @primes, $num;
next;
}
my $is_prime = 1;
for (2 .. $num - 1) {
if ($num % $_ == 0) {
$is_prime = 0;
}
}
if ($is_prime == 1) {
push @primes, $num;
}
}

▸ 366.103 sec
▸ oh...
▸ 10 6
▸

▸  
my @primes = ();
for my $num (2 .. 100_000) {
if ($num == 2) {
push @primes, $num;
next;
}
my $is_prime = 1;
for (2 .. $num - 1) {
if ($num % $_ == 0) {
$is_prime = 0;
last;
}
}
push @primes, $num;
}
}

▸ 31.404 sec
▸ 1/10
▸ 5
▸ 2  
25
▸

▸
my @primes = ();
for my $num (2 .. 100_000) {
if ($num == 2) {
push @primes, $num;
next;
}
my $is_prime = 1;
for (@primes) {
if ($num % $_ == 0) {
$is_prime = 0;
last;
}
}
push @primes, $num;
}
}

▸
▸
▸ 4 = 2 x 2 60 = 2 x 2 x 3 x 5
▸ 4 2  
60 2 3 5

▸ @primes
▸
▸  
@primes
▸ 3.191 sec
▸ 1/10

▸ ……
▸
▸
▸ 91 7 13
▸ 91 13
▸ 91 13

▸ N  
√N
▸ 91 9.53...
▸ 2 9 10 90

▸ √N
my @primes = ();
for my $num (2 .. 100_000) {
if ($num == 2) {
push @primes, $num;
next;
}
my $is_prime = 1;
for (@primes) {
last if $_ > sqrt($num);
if ($num % $_ == 0) {
$is_prime = 0;
last;
}
}
push @primes, $num;
}
}

▸ 0.126 sec
▸ 1
▸ 1/3000

……
▸
my @primes = ();
for my $num (2 .. 100_000) {
if ($num == 2) {
push @primes, $num;
next;
}
my $is_prime = 1;
for (@primes) {
last if $_ > sqrt($num);
if ($num % $_ == 0) {
$is_prime = 0;
last;
}
}
push @primes, $num;
}
}

▸
my @numbers = (1) x 100_001;
$numbers[0] = 0;
$numbers[1] = 0;
for my $num (2 .. sqrt(100_000)) {
if ($numbers[$num]) {
for (2 .. (100_000 / $num)) {
$numbers[$num * $_] = 0;
}
}
}

▸ 0.026 sec
▸ ……
▸
▸
▸
▸

▸ memoization ( not memonization )
▸  
▸
▸

▸
# normal
sub fib {
my $number = shift;
return 1 if $number == 1 || $number == 2;
return fib($number - 1) + fib($number - 2);
}
# memoize
my %memo;
sub fib {
my $number = shift;
return 1 if $number == 1 || $number == 2;
return $memo{$number} if $memo{$number};
$memo{$number} = fib($number - 1) + fib($number - 2);
return $memo{$number};
}

▸ 30
▸ normal: 545.545 msec / memoize: 0.114 msec
▸
▸ is_prime
▸ is_prime

▸ Perl
▸ Memoise
▸ normal memoize('fib');
▸
▸
▸ Memoise 30 18.654 msec

List::Compare
▸ 10
▸
▸ List::Compare get_Lonly

List::Compare
▸ List::Compare
# List::Compare
my $lc = List::Compare->new(@primes, @fibs);
my @left_only = $lc->get_Lonly;
# normal
my %exists;
%exists = map { $_ => 1 } @primes;
for (@fibs) {
$exists{$_} = 0 if ($exists{$_});
}
my @left_only = grep { $exists{$_} == 1 } keys %exists;

List::Compare
▸ List::Compare: 35.733 msec / normal: 17.769 msec
▸ List::Compare  
1 List::Compare
▸ List::Compare new

▸ 1
▸ push join  
# push -> join
my @str;
for (1 .. 1_000_000) {
push @str, "The quick brown fox jumps over the lazy dog.";
}
my $result = join "", @str;
# concat
my $result;
for (1 .. 1_000_000) {
$result .= "The quick brown fox jumps over the lazy dog.";
}

▸
▸  
# multiple 2, 4 times
my @numbers;
for (1 .. 100_000_000) {
push @numbers, $_ * 2 * 2 * 2 * 2;
}
# multiple 16, 1 time
my @numbers;
for (1 .. 100_000_000) {
push @numbers, $_ * 16;
}

▸
▸
# function in loop
sub sum {
my ($x, $y) = @_;
return $x + $y;
}
my $total = 0;
for (1 .. 1_000_000) {
$total = sum($total, $_);
}
# loop in function
sub sum_list {
my ($list) = @_;
my $result;
for (@$list) {
$result += $_;
}
return $result;
}
my $total = sum_list([1 .. 1_000_000]);

▸ Function in Loop: 360.701 msec
▸ Loop in Function: 94.884 msec
▸  
Function in Loop
▸

Struct of Arrays
▸
▸ Perl
▸ Struct of Arrays (SoA) Array of Structs (AoS)
▸ AoS
▸  
SoA

Struct of Arrays
▸ SoA AoS Clone
# Array of Structs
my $aos = [];
for (1 .. 100_000) {
push @$aos, { number => $_, double => $_ * 2 };
}
my $copy = clone($aos);
# Struct of Arrays
my $soa = {};
my @numbers;
my @doubles;
my $count;
for (1 .. 100_000) {
push @numbers, $_;
push @doubles, $_ * 2;
}
$soa = { number => @numbers, double => @doubles };
my $copy = clone($soa);

Struct of Arrays
▸ AoS: 640.302 msec / SoA: 215.323 msec
▸ SoA Clone
▸
▸ AoS: 24,800,144 bytes / SoA: 6,400,424 bytes

▸
▸ ……
▸
▸ DB ……
▸
▸

▸ DB
▸
▸
▸ DB/KVS
▸
▸
▸ CDN

First step of Performance Tuning

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