Developing applications for performance

@papa_ﬁre
Developing Applications
for Performance
by Leon Fayer

@papa_ﬁre
{me}
‣ developer ++
‣ i drink and i ﬁx code
‣ vp @ OmniTI
‣ make slow go fast

@papa_ﬁre
disclaimers
1. performance is technology agnostic

@papa_ﬁre
disclaimers
2. performance != scalability

@papa_ﬁre
disclaimers
3. there is more to performance

@papa_ﬁre
disclaimers
3. there is more to performance
4. it’s (almost) all about web

@papa_ﬁre
it improves user experience

@papa_ﬁre
(and as a result)
it effects business

@papa_ﬁre
“
Just a 100-millisecond delay
in load time hurt conversion
rate by 7%
https://www.soasta.com/wp-content/uploads/2017/04/State-of-Online-Retail-Performance-Spring-2017.pdf

@papa_ﬁre
it saves money
(in production)

@papa_ﬁre
50 users/sec
served by 2 web servers
costing $300/month
x
x
$600/month

@papa_ﬁre
1000 users/sec
costing $300/month
x
x
$12,000/month

@papa_ﬁre
this is why cloud doesn’t solve
all your problems

@papa_ﬁre
only slide on scalability
‣ don’t scale instead of improving
performance
‣ keep scaling in mind during design

@papa_ﬁre
what can you optimize?

@papa_ﬁre
High Performance
Web Sites
by Steve Souders

@papa_ﬁre
SPOF
(single point of failure)

@papa_ﬁre
(in the world of web)
service integrations

@papa_ﬁre
codercruise.com
http://requestmap.webperf.tools

@papa_ﬁre
what happens when they fail?

@papa_ﬁre
http://www.webpagetest.org/

@papa_ﬁre
3rd party = no control

@papa_ﬁre
one failure is enough

@papa_ﬁre
- site implement Facebook Connect
- site implement Facebook Connect incorrectly
- site load times increase 4x
- Facebook has issues
- Facebook keeps connections open
- site load times increase 500x (until timeout)
- Facebook crashes
- site crashes
- game over

@papa_ﬁre
services can be your own
PSA

@papa_ﬁre
tips
only connect to the services you need

@papa_ﬁre
tips
avoid external connection on critical path

@papa_ﬁre
tips
make external calls asynchronously

@papa_ﬁre
tips
trap errors and timeouts

@papa_ﬁre
tips
trap errors and timeouts
have a fallback plan

@papa_ﬁre
http://use-the-index-luke.com
Markus Winand

@papa_ﬁre
$blog = new Blog(‘leon’);
$posts = $blog->get_all_posts();
foreach ($posts as $post) {
$post->comments = $post->get_comments();
}

@papa_ﬁre
$dbh = new DB(…);
$sth = $dbh->prepare("select * from posts where author = ?”);
$sth->execute(‘leon’);
$posts = array();
foreach ($sth->fetchAll() as $p) {
$post = new Post();
$post->id = $p->[‘id’];
$post->title = $p->[‘title’];
$post->author = $p->[‘author’];
$post->body = $p->[‘body’];
array_push($posts, $post);
}
$dbh2 = new DB(…);
$sth_comm = $dbh2->prepare("select * from post_comments where post_id = ?");
$sth_comm->execute($post->post_id);
foreach(sth_comm->fetchAll() as $c) {
$comment = new Comment();
$comment->id = $c->[‘id’];
$comment->author = $c->[‘author’];
$comment->body = $c->[‘body’];
array_push($post->comments, $comment);
}
}

@papa_ﬁre
$dbh = new DB(…);
$sth = $dbh->prepare("select * from blogs where username = ?”);
$posts = array();
$post = new Post();
$post->id = $p->[‘id’];
}
}
}

@papa_ﬁre
$dbh = new DB(…);
$posts = array();
$post = new Post();
$post->id = $p->[‘id’];
}
}
}

@papa_ﬁre
1 post = 2 queries
10 posts = 11 queries
100 posts = 101 queries
…

@papa_ﬁre
but that’s not all

@papa_ﬁre
$dbh = new DB(…);
$posts = array();
$post = new Post();
$post->id = $p->[‘id’];
}
}
}
$dbh = new DB(…);

@papa_ﬁre
$dbh = new DB(…);
$sth = $dbh->prepare("select [list columns you need] from posts p, post_comments c
where p.id = c.post_id
and p.username = ?
order by p.id DESC”);
$posts = array();
$post = new Post();
$active_pid = 0;
if ($post->id != $active_pid) { // if this row is for the post we’re working on
if ($post->id) {
}
$active_pid = $post->id; // getting comments for this post
$post = new Post();
$post->id = $p->[‘id’];
}
}

@papa_ﬁre
$dbh = new DB(…);
$sth = $dbh->prepare("select [list columns you need] from posts p, post_comments c
and p.username = ?
$posts = array();
$post = new Post();
$active_pid = 0;
if ($post->id != $active_pid) { // if this row is for the post we’re working on
if ($post->id) {
}
$post = new Post();
$post->id = $p->[‘id’];
}
}
$dbh = new DB(…);
$sth = $dbh->prepare("select [list columns you need]
from posts p, post_comments c
and p.username = ?

@papa_ﬁre
1 post = 1 query
10 posts = 1 query
100 posts = 1 query
…

@papa_ﬁre
Common Table Expressions (CTE)
to further reduce a number of
queries
http://omniti.com/seeds/writable-ctes-improve-performance
PSA

@papa_ﬁre
$blog = new Blog(‘leon’);
$posts = $blog->get_all_posts_with_comments();

@papa_ﬁre
$posts = $blog->get_all_posts_with_comments();
$dbh = new DB(…);
$sth = $dbh->prepare("select [list columns you need]
from posts p, post_comments c
and p.username = ?
$posts = array();
$post = new Post();
$active_pid = 0;
if ($post->id != $active_pid) { // if this row is for the post we’re
if ($post->id) {
}
$post = new Post();
$post->id = $p->[‘id’];
}
}

@papa_ﬁre
that’s awesome!
(right?)

@papa_ﬁre
do you know what’s
under the hood?

@papa_ﬁre
you have no idea how they work

@papa_ﬁre
1. machine-generated
2. object construction overhead
3. false sense of control

@papa_ﬁre
“
think about ORM as the
most junior developer you’ve
ever worked with

@papa_ﬁre
select * from
(
select bannerid, caption, client_url, image_file, sponsorid, weight from
(
select V.bannerid, V.impressions, B.caption, B.client_url, B.image_file, s.sponsorid,
s.weight,
row_number() over (partition by s.sponsorid order by s.weight desc) ranking
FROM
(
-- This level gives me a list of banners sorted by least seen,and then by highest
weight
select valid.bannerid, valid.totalweight, count(I.timestamp) as impressions FROM
(
-- This level gets me a list of banners that are valid for display
select b.bannerid,
-- Add up the weight from 4 sources. Banner weight, and weight for
each data item they match
decode( decode(bitand(u.STATE_BM1,b.STATE_BM1),0,0,1) +
decode(bitand(u.STATE_BM2,b.STATE_BM2),0,0,1) +
decode(bitand(u.STATE_BM3,b.STATE_BM3),0,0,1),
0,0,b.STATE_WT
) +
decode(bitand(u.AGE_BM,b.AGE_BM),0,0,b.AGE_WT)+
decode(bitand(u.GENDER_BM,b.GENDER_BM),0,0,b.GENDER_WT)+
b.weight as totalweight
from tgif.tbl_users u, tgif.tbl_banners b, tgif.tbl_bannerstats bs
where
-- I only care about ME!
u.userid= 1
-- Don't show inactive banners
and b.inactive != 1
-- Only show banners that are currently running
and sysdate < b.end_date and sysdate >=b.start_date
-- Only get the type of banner i'm looking for
and b.type= 3
-- Join on the total stats, and only display banners that
haven't reached their per banner maximums
and b.bannerid = bs.bannerid
and ( b.max_impressions IS NULL OR bs.total_impressions
< b.max_impressions )
and ( b.max_clicks IS NULL OR bs.total_clicks <
b.max_clicks )
and ( b.max_conversions IS NULL OR bs.total_conversions
< b.max_conversions )
-- Ignore any banners that don't match their demographics (ie,
male banner won't go to females)
and ( b.AGE_BM IS NULL OR b.AGE_BM = 0 OR
bitand(u.AGE_BM, b.AGE_BM) != 0 )
and ( b.GENDER_BM IS NULL OR b.GENDER_BM =0 OR
bitand(u.GENDER_BM, b.GENDER_BM) != 0 )
and ( b.STATE_BM1 IS NULL OR b.STATE_BM1 =0 OR
bitand(u.STATE_BM1, b.STATE_BM1) != 0 )
-- But don't show me any banners that I have already signed up
and b.bannerid NOT IN (
SELECT B.bannerid FROM tgif.tbl_bannerconversions C,
tgif.tbl_banners B, tgif.tbl_sponsors sp
WHERE C.USERID=1
AND C.bannerid=B.bannerid
AND B.sponsorid=sp.sponsorid
-- unless they have a conversion interval, and that
interval has expired
AND ( sp.conversion_interval = 0 OR sysdate >
C.timestamp+sp.conversion_interval )
)
-- Don't show me any banners that have SPONSORS that have
reached their maximums
and b.sponsorid NOT IN (
-- I believe this would be better done using HAVING
clauses, but I can't figure it out
-- Take the banners for a sponsor in the bannerstats
table, and get the totals per sponsor
-- return anything that has reached it's maximum
select sponsorid FROM
(
SELECT S.sponsorid, S.max_impressions,
S.max_conversions, S.max_clicks,
sum(total_impressions) as imps,
sum(total_conversions) as convs, sum(total_clicks)
as clicks
FROM tgif.tbl_sponsors S, tgif.tbl_banners B,
tgif.tbl_bannerstats bs
WHERE S.sponsorid=B.sponsorid
AND B.bannerid=bs.bannerid
GROUP BY S.Sponsorid, S.max_impressions,
S.max_conversions, S.max_clicks
) exclude
WHERE ( imps > max_impressions OR convs >=
max_conversions OR clicks > max_clicks )
)
) valid, tgif.tbl_bannerimpressions I
where
valid.bannerid=I.bannerid(+)
and I.userid(+)=1
group by valid.bannerid, valid.totalweight
-- I want to see banners I haven't seen yet, sorted by highest weight, so we sort by number
-- of times that this user has seen this particular banner, then we sort by weight
order by impressions, totalweight DESC
) V, tgif.tbl_banners B, tgif.tbl_sponsors S
where B.bannerid=V.bannerid
and B.sponsorid=S.sponsorid
and S.inactive != 1
and s.sponsorid not in (
) valid, tgif.tbl_bannerimpressions I
where
valid.bannerid=I.bannerid(+)
and I.userid(+)=1
group by valid.bannerid, valid.totalweight
-- I want to see banners I haven't seen yet, sorted by highest weight, so we sort by number
-- of times that this user has seen this particular banner, then we sort by weight
order by impressions, totalweight DESC
) V, tgif.tbl_banners B, tgif.tbl_sponsors S
where B.bannerid=V.bannerid
and B.sponsorid=S.sponsorid
and S.inactive != 1
and s.sponsorid not in (
-- Check the user impression cap to make sure it hasn't been passed by the user
select s.sponsorid from tgif.tbl_banners b, tgif.tbl_sponsors s,
tgif.TBL_BANNERIMPRESSIONS i
where s.sponsorid = b.sponsorid
and b.bannerid = i.bannerid
and i.timestamp >= sysdate - nvl(user_impression_cap_days,100)
and userid = 1
group by s.sponsorid
having count(*) >= max(nvl(user_impression_cap,1000000000))
)
-- Make sure the sponsor is still in the valid table. This table is updated hourly
-- and contains the sponsors that have not gone over their sponsor level frequencies for
-- impressions/conversions/clicks
and s.sponsorid in (select sponsorid from tgif.tbl_active_sponsors)
)
where ranking=1
--Order the banners by sponsor weight, which is handled by the ranking
--order by S.weight
order by impressions, weight desc
)
where rownum <= 10;
would you trust
a junior with
this query?

@papa_ﬁre
object construction is very expensive

@papa_ﬁre
METHOD REAL USER SYS PCPU
Base ORM 6.330 5.771 0.212 94.51

@papa_ﬁre
Base ORM 6.330 5.771 0.212 94.51
SQL without
objects
0.664 0.274 0.120 59.35

@papa_ﬁre
Base ORM 6.330 5.771 0.212 94.51
SQL without
objects
0.664 0.274 0.120 59.35
SQL with ORM
objects
6.354 5.797 0.197 94.34

@papa_ﬁre
get_all_* are the worst

@papa_ﬁre
# return a collection with all articles
articles = Article.all

@papa_ﬁre
# return a collection with all articles
articles = Article.all
# class/object definition
class Article
has_many :authors
has_many :images,
has_many :comments
has_many :related_articles
end

@papa_ﬁre
ORMs are bad
for high-trafﬁc production
for replacing SQL skills

@papa_ﬁre
“
I have yet to ﬁnd a tool built to
avoid using SQL that doesn’t
become more complicated to use
than just learning SQL
John Simone (@j_simone)

@papa_fire
ORMs are not bad
for prototyping
for low-traffic systems
for non-public traffic

@papa_ﬁre
PSA
lazy loading doesn’t solve
all your problems

@papa_ﬁre
if you can’t optimize the problem
hide the problem

@papa_ﬁre
“
there are only two hard
things in Computer Science:
cache invalidation and
naming things Phil Karlton

@papa_ﬁre
is stale content > slow content?

@papa_ﬁre
how valuable is 1 minute?

@papa_ﬁre
100 request/sec
1 minute cache (60 seconds)
x
x
11,998 “cheap” reqs/min
2 “expensive” reqs/min

@papa_ﬁre
① browser
② on-disk
③ in-memory

@papa_ﬁre
cache-control header

@papa_ﬁre
.htaccess
# cache all pages for one month
Header set Cache-Control "max-age=2628000, public"

@papa_ﬁre
.htaccess
# cache static assets for one month
<filesMatch ".(jpg|jpeg|png|gif|js|ico)$">
Header set Cache-Control "max-age=2628000, public"
</filesMatch>

@papa_ﬁre
php
# cache this page for one minute
<? header("Cache-Control: max-age=60"); ?>

@papa_ﬁre
you don’t control browsers

@papa_ﬁre
progressive web applications
(service workers)
https://www.youtube.com/watch?v=3ol3-kvCNeQ
Patrick Meenan, Velocity

@papa_ﬁre
read content from ﬁle

@papa_ﬁre
… external source (API, database)
… processing content again
read content from ﬁle
instead of …

@papa_ﬁre
returnContent() {
return generateContent();
}

@papa_ﬁre
returnContent() {
if (has_cache($cache_file, $cache_ttl)) {
return _read_cache($cache_file);
} else {
return _write_cache($cache_file);
}
}

@papa_ﬁre
###### FS caching
sub _read_cache {
my $cache_file = shift;
open (my $fh, '<', $cache_file)
or die "Can't open file doe reading $!";
read $fh, my $cache_content, -s $fh;
close $fh;
return $cache_content;
}
sub _write_cache {
my $content = generateContent();
open(my $fh, '>', $cache_file)
or die "Could not open file '$cache_file' $!";
print $fh $content;
close $fh;
return $cache_content;
}

@papa_ﬁre
have to manage your own ttl

@papa_ﬁre
sub has_cache {
my $cache_ttl = shift; #in seconds
if (-f $cache_file) {
# in seconds
my $last_updated = (stat($cache_file))[9];
my $now = int (gettimeofday);
my $diff = $now - $last_updated;
return 1 if ($now - $last_updated <= $cache_ttl);
}
return 0;
}

@papa_ﬁre
local or distributed

@papa_ﬁre
function returnContent($article_id) {
$memcache = new Memcache;
$cacheAvailable = $memcache->connect(MEMCACHED_HOST, MEMCACHED_PORT);
if ($cacheAvailable) {
$cached_article = $memcache->get(‘article-’.$article_id);
if (!$cached_article) {
$article = getArticle($article_id);
$memcache->set(‘article-‘.$article_id, $article);
return $article;
} else {
return $cached_article;
}
}
}

@papa_ﬁre
function returnContent($article_id) {
$cacheAvailable = $memcache->connect(MEMCACHED_HOST, MEMCACHED_PORT);
if ($cacheAvailable) {
$article = getArticle($article_id);
$memcache->set(‘article-‘.$article_id, $article);
return $article;
} else {
return $cached_article;
}
}
}
$memcache->set(‘article-‘.$p->[‘article_id’], $article);

@papa_ﬁre
returnContent() {
$content = read_cache($cache_key);
if (!$content) {
$content = generateContent();
write_cache($cache_key, $content);
}
return $content;
}

@papa_ﬁre
remember /get/articles/all ?
(multi-nested ORM function)

@papa_ﬁre
METHOD BASE LOAD
20x TRAFFIC
SPIKE
Base call 5.782 s 12.127 s

@papa_ﬁre
METHOD BASE LOAD
20x TRAFFIC
SPIKE
Base call 5.782 s 12.127 s
Base call with memcache 0.867 s 0.922 s

@papa_ﬁre
not just for db results

@papa_ﬁre
$memcache->set($uri, $html);

@papa_ﬁre
doesn’t have to be 100% static

@papa_ﬁre
don’t forget to purge

@papa_ﬁre
careful what you cache

@papa_ﬁre
“pretty” urls
/my/proﬁle

@papa_ﬁre
“ugly” urls
/prodlist.php?SID=a3e9590a-6598-11e7-907b-a6006ad3dba0

@papa_ﬁre
reverse HTTP proxy

@papa_ﬁre
Apache Trafﬁc Server, Varnish

@papa_ﬁre
CDN
Akamai, Fastly

@papa_ﬁre
rule-based controls

@papa_ﬁre
use as many or as few

@papa_ﬁre
remember the part about critical path?

@papa_ﬁre
anything not related
to the immediate outcome
should not be
in the critical path

@papa_ﬁre
router.post('/register', function(req, res){
var user = new User(req.body);
user.save( function(err) {
if (!err) {
user.savePreferences(req.pref);
user.sendWelcomeEmail();
res.render(‘first_time_welcome',
{ title: 'Welcome' + user.name,
errors: [err] });
}
});
});

@papa_ﬁre
if (!err) {
errors: [err] });
}
});
});

@papa_ﬁre
User.sendWelcomeEmail = function(callback){
if (!do_not_email(user.email) {
var email = new Email();
email.subject = "Welcome " + user.firstname;
email.cta = getDealoftheDay();
email.secondary = getOffers(user);
email.generateBody(user, function() {
email.send();
});
}
};

@papa_ﬁre
does it have to be done now?

@papa_ﬁre
if (!err) {
sendToQueue(‘welcome email’,user);
errors: [err] });
}
});
});
sendToQueue(‘welcome email’,user);

@papa_ﬁre
queueing (v.) - putting things
somewhere else
to deal with later

@papa_ﬁre
where?
1. in-memory (RabbitMQ, SQS)
2. persistant (database)

@papa_ﬁre
optimize everything
(right?)

@papa_ﬁre
“premature optimization
is the root of all evil
Donald Knuth

@papa_ﬁre
improvements should be …
1. needed

@papa_ﬁre
1. needed
2. incremental

@papa_ﬁre
1. needed
2. incremental
3. measurable

@papa_ﬁre
always think about
performance

@papa_ﬁre
there is an exception
to every rule
parting tip

@papa_ﬁre
thank you
questions?

Developing applications for performance

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