Prep for Quora

• Consistency (eventual consistency - Dr. Qadeer’s lesson?)

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• Performance: Pycache: in-process caching
• Scalability and performance: Qmessage: handling billions of tasks per day
• Performance: optimizing memcached efficiency
• Performance: asynchronous programming in python: asynq
• Performance: Faster paint times
• Availability: Ensuring quora’s resilience to disaster

Internal details

• Asynq
• MemcacheD latency improvement
• NLP for correcting question
• Fast paint times, client side improvement
• Quora server specs What’s the issue:
• Horizontal scaling is not as simple as adding more master nodes. Communication with other components such as caching can become a problem.
• Network I/O becomes a bottleneck. Even if the number of parallel processes and CPU power is increased, network latency cannot be reduced beyond a

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