Rails Performance Michael Koziarski michael@koziarski.com Rails - - PowerPoint PPT Presentation

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Rails Performance Michael Koziarski michael@koziarski.com Rails - - PowerPoint PPT Presentation

May 31, 2023 306 likes •1.73k views

Rails Performance Michael Koziarski michael@koziarski.com Rails Performance Relax Programmers Love Optimisation Science Based Objective Provable Opportunity Cost Is this optimisation really the best use of your time? Two Justifications

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Rails Performance

Michael Koziarski michael@koziarski.com

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Rails Performance

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Relax

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Programmers Love Optimisation

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Science Based

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Objective

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Provable

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Opportunity Cost

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Is this optimisation really the best use of your time?

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Two Justifications

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Hardware Costs

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Responsiveness

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Hardware Costs

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Profits = Revenue - Costs

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Hardware isn’t all of your costs

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Hardware costs are not continuous

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Hardware costs are not continuous

Unless you’re huge

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Hardware costs are not continuous

Unless you’re huge You’re not huge

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Hardware is basically free

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Hardware is basically free

Compared to staff

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Hardware Cost Driven Optimisation

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Example.com

  • 4 Servers at $299/mo
  • Total hosting of ~ $1,200/mo
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SLIDE 23

Example.com

  • 10% performance improvement across the

board!

  • Leads to a $120/mo saving...
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SLIDE 24

Example.com

  • Staff costing 60-80k/yr
  • $28-$38/hr
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It almost certainly wasn’t worth it

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Responsiveness

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Much more Important

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Slow applications are no fun to use

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No Users

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No Revenue

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No Business

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Not about requests per second

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Seconds per request

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Perceived Performance

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853ms

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3:00

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PHP is 0.4% of the total

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Assume it gets 50% faster

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The net saving is 0.2%

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Not Noticeable

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Frontend Performance should be your Priority

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YSlow

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Fix all of these

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I’ve done all that!

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Optimisation Procedure

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Optimisation Procedure

  • 1. Figure out what’s slow
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Optimisation Procedure

  • 1. Figure out what’s slow
  • 2. Figure out why it’s slow
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SLIDE 56

Optimisation Procedure

  • 1. Figure out what’s slow
  • 2. Figure out why it’s slow
  • 3. Make it faster
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  • 1. Find What’s Slow
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Choose your target

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Choose your target

  • Slower than the rest
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Choose your target

  • Slower than the rest
  • Heavily used
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Grep your Logs

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Grep your Logs

Completed in 220ms (View: 72, DB: 5)

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Grep your Logs

Completed in 220ms (View: 72, DB: 5) X-Runtime: 0.00783

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PL Analyze

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  • 1b. Cheat
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Caching!

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HTTP Caching

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ETags

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ETags

ETag: b4c2fedde6926a5ee6ed8cd5cc995592

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ETags

ETag: b4c2fedde6926a5ee6ed8cd5cc995592 If-None-Match: b4c2fedde6926a5ee6ed8cd5cc995592

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ETags

ETag: b4c2fedde6926a5ee6ed8cd5cc995592 If-None-Match: b4c2fedde6926a5ee6ed8cd5cc995592





def
handle_etag 





etag!
[@user.id,
@user.updated_at] 



end

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Last-Modified

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Last-Modified

Last-Modified: Sun, 28 Sep 2008 19:38:05 GMT

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Last-Modified

Last-Modified: Sun, 28 Sep 2008 19:38:05 GMT If-Not-Modified-Since: Sun, 28 Sep 2008 19:38:05 GMT

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Last-Modified

Last-Modified: Sun, 28 Sep 2008 19:38:05 GMT If-Not-Modified-Since: Sun, 28 Sep 2008 19:38:05 GMT





def
handle_last_modified 





last_modified!
@user.updated_at 



end

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SLIDE 83

Expires





def
add_expires 





response.headers["Expires"]
=
@user.updated_at
+
1.hour 



end

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SLIDE 84

Rails Caching

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Fragment Caching

<%
cache
[@user,
"dashboard"]
do
%> 

<%=
render
:partial=>"complex_expensive_dashboard"
%> <%
end
%>

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SLIDE 86

Action Caching

caches_action
:index

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Model Caching

class
Comment
<
ActiveRecord::Base 

acts_as_cached
:ttl=>1.hour end

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Memcache

  • Seriously Fast
  • Seriously Scalable
  • LRU Cache Expunging
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Cache Generations

There are only two hard things in Computer Science: cache invalidation and naming things

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Cache Generations

There are only two hard things in Computer Science: cache invalidation and naming things So let’s not explicitly invalidate anything

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Cache Generations

cache
["user",
@user.id]

cache
["user_profile",
@user.id]


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Cache Generations

cache
["user",
@user.id,
@user.generation]

cache
["user_profile",
@user.id,
@user.generation]


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Cache Generations

class
User
<
ActiveRecord::Base 

before_save
:increment_generation 

 

def
increment_generation 



self.generation
+=
1
 

end end

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Cache Generations

class
Friendship
<
ActiveRecord::Base 

belongs_to
:owner,
:class_name=>"User" 

belongs_to
:friend,
:class_name=>"User" 

before_save
:increment_both_users 

 

def
increment_both_users 



[owner,
friend].map
&:increment_generation 

end end

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  • 2. Figure out why it’s

slow

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Never Guess

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You’re never right

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Slow Trac

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Slow Trac

  • Use a new PostgreSQL driver
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Slow Trac

  • Use a new PostgreSQL driver
  • Use mod_python, not tracd
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Slow Trac

  • Use a new PostgreSQL driver
  • Use mod_python, not tracd
  • It’s spammers, add a better spam plugin
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Slow Trac

@project.head_revision

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Slow Trac

SELECT
max(rev)
FROM
rev;

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Slow Trac

SELECT
rev
FROM
rev
 ORDER
BY
‐LENGTH(rev),
rev
 LIMIT
1;

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Slow Trac

SELECT
max(rev::integer)
FROM
rev;

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SLIDE 106

Slow Trac

CREATE
INDEX
rev_as_INT
 ON
rev(rev::integer);

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SLIDE 107

Performance Tests

New in 2.2

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SLIDE 108

Performance Tests

require
'performance/test_helper' class
SessionActionsTest
<
ActionController::PerformanceTest

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SLIDE 109

Performance Test



def
test_fetching_index 



get
"/sessions" 

end 

def
test_fetching_index_all 



get
"/sessions?all=true" 

end

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SLIDE 110

Performance Test

rake test:benchmark

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Performance Test

rake test:benchmark

SessionActionsTest#test_fetching_index
(54
ms
warmup) 







process_time:
70
ms 













memory:
0.00
KB 












objects:
0 












gc_runs:
0 












gc_time:
0
ms

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SLIDE 112

Performance Test



def
setup 



u
=
users(:koz) 



post
authenticate_url,
... 



50.times
do
|i| 





u.sessions.create! 



end 

end

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Performance Tests

SessionActionsTest#test_fetching_index
(254
ms
warmup) 







process_time:
270
ms 













memory:
0.00
KB 












objects:
0 












gc_runs:
0 












gc_time:
0
ms

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Performance Tests

rake test:profile

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Performance Tests

SessionActionsTest#test_fetching_index_process_time_graph.html

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Performance Tests

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Performance Tests

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Performance Tests

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Performance Tests

SessionActionsTest#test_fetching_index_all_objects_graph.html

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Performance Tests

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Performance Tests

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Performance Tests

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Performance Tests

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  • 3. Make it Faster
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<%=
image_tag
"red.png"
%>

<img
src="/images/red.png?1212215830"
/>

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<%=
image_tag
"onepixel.gif"
%>

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Route Generation

<p>Have
you
considered
<%=
link_to
"Paying
me
money",
 


































awesome_consultant_url
%></p>

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Route Generation

<p>Have
you
considered
<%=
link_to
"Paying
me
money",
 


































awesome_consultant_url
%></p>

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N+1 Queries

<%
@user.posts.each
do
|post|
%> 



<p><%=
link_to
post.title,
post_url(post)
%></p> <%
end
%>

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N+1 Queries

User.find(params[:id],
:include=>[:posts])

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N+1 Queries

<%
@user.posts.each
do
|post|
%> 



<p> 







<%=
link_to
post.title,
post_url(post)
%> 








by
 







<%=
post.author.name
%> 



</p> <%
end
%>

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Garbage Collection

PageShowTest#test_show
(246
ms
warmup) 







process_time:
183
ms 













memory:
1696.26
KB 












objects:
116280 












gc_runs:
0 












gc_time:
42
ms

22% in GC

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Garbage Collection

http://github.com/skaes/railsbench

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Garbage Collection

#
greatly
increase
initial
heap
slots
available
(60x
more)
 RUBY_HEAP_MIN_SLOTS=600000
 #
ensure
lots
of
heap
slots
are
freed
after
GC
(25x
more)
 RUBY_HEAP_FREE_MIN=100000
 #
and
don’t
run
GC
unless
we're
over
60MB
heap
(7.5x
more)
 RUBY_GC_MALLOC_LIMIT=60000000

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Conclusion

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Fix Frontend Performance First

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Use HTTP

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Cache with memcache

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Profile, don’t guess

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Don’t forget GC when profiling

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Questions?

Michael Koziarski michael@koziarski.com