🌐Latency Vs Throughput
Latency
Latency is the time taken for a request to travel from the client to the server and back. It's a measure of the delay before a transfer of data begins following an instruction for its transfer. Latency is often measured in milliseconds (ms) or microseconds (µs).
Low Latency: Indicates that there is minimal delay in data transfer.
High Latency: Indicates that there is a significant delay in data transfer.
Factors Affecting Latency:
Network Speed: Slower networks increase latency.
Distance: Longer physical distances between the client and server can increase latency.
Processing Time: Time taken by the server to process a request.
Congestion: High traffic on the network can increase latency.
A feature that issues hundreds of database queries per page request would likely never leave the prototype stage because it would be too slow and expensive. This may result in the high latency over period of time.
Quote taken from the scaling cache at Facebook research paper
Scaling Memcache at FacebookThroughput
Throughput is the amount of data that can be processed by a system within a given amount of time. It is often measured in bits per second (bps), requests per second (RPS), or transactions per second (TPS).
High Throughput: Indicates that the system can handle a large number of requests or process a large amount of data in a short time.
Low Throughput: Indicates that the system can handle only a few requests or process a small amount of data in the same time period.
Factors Affecting Throughput:
Bandwidth: Higher bandwidth can increase throughput.
Concurrency: The ability of the system to handle multiple requests simultaneously.
Resource Availability: Availability of CPU, memory, and other resources.
Efficiency of Algorithms: More efficient algorithms can process data faster.
Balancing Latency and Throughput
In system design, there's often a trade-off between latency and throughput:
Low Latency vs. High Throughput: Systems designed for low latency often process fewer requests at a time to ensure quick response times, potentially reducing overall throughput.
High Throughput vs. Low Latency: Systems designed for high throughput may process many requests simultaneously, which can introduce delays and increase latency.
Use Cases
Low Latency Systems: Real-time applications like video conferencing, online gaming, and financial trading platforms where quick response times are crucial.
High Throughput Systems: Batch processing systems, data analytics platforms, and high-traffic web servers where the ability to handle large volumes of data is more important than immediate response times.
Example
Video Streaming Service:
Low Latency: Ensures that when a user clicks play, the video starts with minimal delay.
High Throughput: Ensures that the service can stream video to millions of users simultaneously.
Interview Questions
General Understanding
Define latency and throughput. How do they differ?
Why is it important to balance latency and throughput in a system?
Can you explain the relationship between latency and throughput?
Latency
What factors can contribute to high latency in a system?
How can you reduce latency in a web application?
Describe a scenario where low latency is more important than high throughput.
What are some techniques to measure and monitor latency in a distributed system?
How does the geographical location of servers impact latency?
Throughput
What factors can affect the throughput of a system?
How can you increase the throughput of a database system?
Describe a scenario where high throughput is more important than low latency.
What are some common bottlenecks that can limit throughput?
How do you measure and monitor throughput in a system?
Trade-offs and Design
Describe a situation where improving throughput might negatively impact latency. How would you handle this trade-off?
How would you design a system to optimize both latency and throughput?
Can you provide an example of a system where both low latency and high throughput are critical?
Explain how load balancing can affect both latency and throughput.
Real-world Scenarios
How would you design a video streaming service to handle millions of users simultaneously? What would you prioritize: latency or throughput?
Imagine you are designing a real-time multiplayer game. What strategies would you use to ensure low latency?
How would you handle a situation where a sudden spike in traffic causes high latency and low throughput in your application?
Technical Solutions
What is caching, and how can it help reduce latency?
Explain the role of Content Delivery Networks (CDNs) in reducing latency and increasing throughput.
How do asynchronous processing and queuing systems impact latency and throughput?
Describe how sharding can be used to improve throughput in a database.
What is the impact of database indexing on latency and throughput?
Performance Monitoring
What tools and techniques would you use to monitor latency and throughput in a production system?
How would you diagnose and troubleshoot high latency issues in a distributed system?
What metrics would you track to ensure your system meets performance requirements for both latency and throughput?
Advanced Topics
How does network latency differ from application latency, and how can each be optimized?
What is the role of backpressure in managing throughput in a streaming data application?
Explain the concept of tail latency and its importance in system performance.
How can microservices architecture affect latency and throughput?
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