> Term
Latency
The delay before a transfer of data begins following an instruction for its transfer, or the time it takes for a data packet to travel from a source to a destination.
Detailed Explanation
Latency is the time interval between a user action or system request and the start of the corresponding response. It is a fundamental metric in distributed systems, networking, and user experience. While throughput measures how much data can be transferred over time, latency measures how fast a single piece of data can be transferred.
Latency is often measured in milliseconds (ms) and broken down into percentiles (e.g., p95, p99) to capture outlier behaviors instead of just relying on averages.
Why It Matters
High latency directly degrades user experience, increases request timeouts, and leads to cascaded queue buildups in distributed services.
Common Failure Mode
Practical Example
Production Manifestation
Users experience sluggish UI responses, API calls start timing out, and downstream services accumulate connection pool exhaustion.
Frequently Asked Questions
What is Latency in short?
The delay before a transfer of data begins following an instruction for its transfer, or the time it takes for a data packet to travel from a source to a destination.
What is the most common failure mode?
Network congestion, inefficient database queries lacking indexes, blocking I/O operations, or geographic distance between the client and the server.
AI Summary
The delay before a transfer of data begins following an instruction for its transfer, or the time it takes for a data packet to travel from a source to a destination. High latency directly degrades user experience, increases request timeouts, and leads to cascaded queue buildups in distributed services.