{"id":"appendix","title":"Appendix","sections":[{"id":"overview","title":"Overview","html":"

You'll sometimes be asked to do 'back-of-the-envelope' estimates. For example, you might need to determine how long it will take to generate 100 image thumbnails from disk or how much memory a data structure will take. The Powers of two table and Latency numbers every programmer should know are handy references.

","headings":[]},{"id":"powers-of-two-table","title":"Powers of two table","html":"

Powers of two table

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Power           Exact Value         Approx Value        Bytes\n---------------------------------------------------------------\n7                             128\n8                             256\n10                           1024   1 thousand           1 KB\n16                         65,536                       64 KB\n20                      1,048,576   1 million            1 MB\n30                  1,073,741,824   1 billion            1 GB\n32                  4,294,967,296                        4 GB\n40              1,099,511,627,776   1 trillion           1 TB
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Source(s) and further reading

\n","headings":[{"id":"powers-of-two-table","title":"Powers of two table","depth":3},{"id":"sources-and-further-reading-13","title":"Source(s) and further reading","depth":4}]},{"id":"latency-numbers-every-programmer-should-know","title":"Latency numbers every programmer should know","html":"

Latency numbers every programmer should know

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Latency Comparison Numbers\n--------------------------\nL1 cache reference                           0.5 ns\nBranch mispredict                            5   ns\nL2 cache reference                           7   ns                      14x L1 cache\nMutex lock/unlock                           25   ns\nMain memory reference                      100   ns                      20x L2 cache, 200x L1 cache\nCompress 1K bytes with Zippy            10,000   ns       10 us\nSend 1 KB bytes over 1 Gbps network     10,000   ns       10 us\nRead 4 KB randomly from SSD*           150,000   ns      150 us          ~1GB/sec SSD\nRead 1 MB sequentially from memory     250,000   ns      250 us\nRound trip within same datacenter      500,000   ns      500 us\nRead 1 MB sequentially from SSD*     1,000,000   ns    1,000 us    1 ms  ~1GB/sec SSD, 4X memory\nHDD seek                            10,000,000   ns   10,000 us   10 ms  20x datacenter roundtrip\nRead 1 MB sequentially from 1 Gbps  10,000,000   ns   10,000 us   10 ms  40x memory, 10X SSD\nRead 1 MB sequentially from HDD     30,000,000   ns   30,000 us   30 ms 120x memory, 30X SSD\nSend packet CA->Netherlands->CA    150,000,000   ns  150,000 us  150 ms\n\nNotes\n-----\n1 ns = 10^-9 seconds\n1 us = 10^-6 seconds = 1,000 ns\n1 ms = 10^-3 seconds = 1,000 us = 1,000,000 ns
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Handy metrics based on numbers above:

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Latency numbers visualized

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\"Diagram\"

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Source(s) and further reading

\n","headings":[{"id":"latency-numbers-every-programmer-should-know","title":"Latency numbers every programmer should know","depth":3},{"id":"latency-numbers-visualized","title":"Latency numbers visualized","depth":4},{"id":"sources-and-further-reading-14","title":"Source(s) and further reading","depth":4}]},{"id":"additional-system-design-interview-questions","title":"Additional system design interview questions","html":"

Additional system design interview questions

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Common system design interview questions, with links to resources on how to solve each.

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QuestionReference(s)
Design a file sync service like Dropboxyoutube.com
Design a search engine like Googlequeue.acm.org
stackexchange.com
ardendertat.com
stanford.edu
Design a scalable web crawler like Googlequora.com
Design Google docscode.google.com
neil.fraser.name
Design a key-value store like Rediscodecapsule.com
allthingsdistributed.com
Design a cache system like Memcachedslideshare.net
Design a recommendation system like Amazon'shulu.com
ijcai13.org
Design a tinyurl system like Bitlyn00tc0d3r.blogspot.com
Design a chat app like WhatsApphighscalability.com
Design a picture sharing system like Instagramhighscalability.com
highscalability.com
Design the Facebook news feed functionquora.com
quora.com
slideshare.net
Design the Facebook timeline functionfacebook.com
highscalability.com
Design the Facebook chat functionerlang-factory.com
facebook.com
Design a graph search function like Facebook'sfacebook.com
facebook.com
facebook.com
Design a content delivery network like CloudFlarefigshare.com
Design a trending topic system like Twitter'smichael-noll.com
snikolov .wordpress.com
Design a random ID generation systemblog.twitter.com
github.com
Return the top k requests during a time intervalcs.ucsb.edu
wpi.edu
Design a system that serves data from multiple data centershighscalability.com
Design an online multiplayer card gameindieflashblog.com
buildnewgames.com
Design a garbage collection systemstuffwithstuff.com
washington.edu
Design an API rate limiterhttps://stripe.com/blog/
Design a Stock Exchange (like NASDAQ or Binance)Jane Street
Golang Implementation
Go Implementation
Add a system design questionContribute
","headings":[{"id":"additional-system-design-interview-questions","title":"Additional system design interview questions","depth":3}]},{"id":"real-world-architectures","title":"Real world architectures","html":"

Real world architectures

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Articles on how real world systems are designed.

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\n \"Diagram\"\n
\n Source: Twitter timelines at scale\n

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Don't focus on nitty gritty details for the following articles, instead:

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TypeSystemReference(s)
Data processingMapReduce - Distributed data processing from Googleresearch.google.com
Data processingSpark - Distributed data processing from Databricksslideshare.net
Data processingStorm - Distributed data processing from Twitterslideshare.net
Data storeBigtable - Distributed column-oriented database from Googleharvard.edu
Data storeHBase - Open source implementation of Bigtableslideshare.net
Data storeCassandra - Distributed column-oriented database from Facebookslideshare.net
Data storeDynamoDB - Document-oriented database from Amazonharvard.edu
Data storeMongoDB - Document-oriented databaseslideshare.net
Data storeSpanner - Globally-distributed database from Googleresearch.google.com
Data storeMemcached - Distributed memory caching systemslideshare.net
Data storeRedis - Distributed memory caching system with persistence and value typesslideshare.net
File systemGoogle File System (GFS) - Distributed file systemresearch.google.com
File systemHadoop File System (HDFS) - Open source implementation of GFSapache.org
MiscChubby - Lock service for loosely-coupled distributed systems from Googleresearch.google.com
MiscDapper - Distributed systems tracing infrastructureresearch.google.com
MiscKafka - Pub/sub message queue from LinkedInslideshare.net
MiscZookeeper - Centralized infrastructure and services enabling synchronizationslideshare.net
Add an architectureContribute
","headings":[{"id":"real-world-architectures","title":"Real world architectures","depth":3}]},{"id":"company-architectures","title":"Company architectures","html":"

Company architectures

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CompanyReference(s)
AmazonAmazon architecture
CinchcastProducing 1,500 hours of audio every day
DataSiftRealtime datamining At 120,000 tweets per second
DropboxHow we've scaled Dropbox
ESPNOperating At 100,000 duh nuh nuhs per second
GoogleGoogle architecture
Instagram14 million users, terabytes of photos
What powers Instagram
Justin.tvJustin.Tv's live video broadcasting architecture
FacebookScaling memcached at Facebook
TAO: Facebook’s distributed data store for the social graph
Facebook’s photo storage
How Facebook Live Streams To 800,000 Simultaneous Viewers
FlickrFlickr architecture
MailboxFrom 0 to one million users in 6 weeks
NetflixA 360 Degree View Of The Entire Netflix Stack
Netflix: What Happens When You Press Play?
PinterestFrom 0 To 10s of billions of page views a month
18 million visitors, 10x growth, 12 employees
Playfish50 million monthly users and growing
PlentyOfFishPlentyOfFish architecture
SalesforceHow they handle 1.3 billion transactions a day
Stack OverflowStack Overflow architecture
TripAdvisor40M visitors, 200M dynamic page views, 30TB data
Tumblr15 billion page views a month
TwitterMaking Twitter 10000 percent faster
Storing 250 million tweets a day using MySQL
150M active users, 300K QPS, a 22 MB/S firehose
Timelines at scale
Big and small data at Twitter
Operations at Twitter: scaling beyond 100 million users
How Twitter Handles 3,000 Images Per Second
UberHow Uber scales their real-time market platform
Lessons Learned From Scaling Uber To 2000 Engineers, 1000 Services, And 8000 Git Repositories
WhatsAppThe WhatsApp architecture Facebook bought for $19 billion
YouTubeYouTube scalability
YouTube architecture
","headings":[{"id":"company-architectures","title":"Company architectures","depth":3}]},{"id":"company-engineering-blogs","title":"Company engineering blogs","html":"

Company engineering blogs

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Architectures for companies you are interviewing with.

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Questions you encounter might be from the same domain.

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Source(s) and further reading

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Looking to add a blog? To avoid duplicating work, consider adding your company blog to the following repo:

\n","headings":[{"id":"company-engineering-blogs","title":"Company engineering blogs","depth":3},{"id":"sources-and-further-reading-15","title":"Source(s) and further reading","depth":4}]}],"sourceFiles":[]}